074 - Engineering not magic, intumescent coatings with Andrea Lucherini

Wojciech Wegrzynski: 0:00

Hello, and welcome to the fire sentence. Show session 74. After the last week solo episodes, we're back to the old interview format. And I again have a nice rising star of the fire safety engineering profession. So I have invited Dr Andrea Lucherini. Who's with a FRISSBE it's an research institue to do that Slovenia. and, uh, It's an interesting project. I'm sure we are going to hear a lot more about it. Hopefully also in the podcast. And Andrea is also affiliated with Ghent university. So. Very prolific young scientists and doing lots of interesting, interesting research But they invited him to talk about his. Research that carries from master thesis through his And university of Queensland. And the subject of this work was on intumescent coatings or intumescent paints. Very interesting, very useful topic. , fire protection system that is used everywhere. Like you see them everywhere. From fire, protecting steel through timber. Closing cavities, closing gaps, insulation joints. Coatings are finding more and more using farsighted engineering, but it's interesting how they work, how they operate, how, what, what makes them differentiate between each other is very, very large subject, to be honest. Very interesting subject. And that's, that's exactly why Andrea is here to understand from a scientist who's really researching this term. What are the things that make intumescent coating work or maybe things that make it not work, or maybe conditions in which they stopped working, or how do they differ from each other? A That's really a huge topic and I hope we've done well to cover at least a. Fundamental principles of that. Cause Th that that's definitely not a subject for a single podcast episode. If you like it, let me know. And I'll guess I'll I can invite Andrea to a follow-up where we can maybe talk a little more about modeling. Or some practical, consequences of the physical properties that are being discussed here. Anyway, no matter what your role in the fire safety engineering is one day you will meet intumescent coatings. So yeah, better learn them and understand how they work. So your job will be easier. So without further ado that spins into and jump into the episode.

Wojciech Węgrzyński: 2:37

Hello everybody. Welcome to the Fire Science Show. Maybe based on the guest affiliation, I should call it Ghent University Show lately. Hey, Andrea. Good to have you.

Andrea Lucherini: 2:48

Hello? Hello, War Check.

Wojciech Węgrzyński: 2:49

today I'm having a nice talk with Dr. Andrea Lucherini uh, FRISSBE Slovenia, which, uh, is under the ZAG in Sloven and also, at Gant University. That's my pun at the start, is you're like third in a row affiliated with Ghent in, in the podcast. That, that makes me quite happy, . Good, good, good place to be. So Andrea, great to have you in the show. I brought you because, uh, there were some publications published lately that, my professional colleagues, uh, has claimed are interesting. If not grow breaking. So I thought okay, if he does your professional opinion, I've I'm gonna get the author on, my podcast and, uh, I've invited you to talk about, into mess pains. Then you were really angry with me for using the word paint and

Andrea Lucherini: 3:36

No, not too angry.

Wojciech Węgrzyński: 3:37

and told me I should refer that I should call them into me coating. let's start with that. What's this technology of intumescent coating and, uh, why should we call it like that?

Andrea Lucherini: 3:49

first of all, the difference between paint and coating. I mean, I don't think that there is any significant difference. What I find, and also by reading a lot of literature, I usually see that quotings is a more professional term, so to describe something that protects, for example, load-bearing structure that we, the use of quotings paint. Sometimes it, to me, it sounds like I'm less professional and more simplistic. Because it's, quoting is, is a much more complex um, material And then hopefully during this episode I'll manage to explain you why it's complicated and also is what attracted me to this sort of field of our research

Wojciech Węgrzyński: 4:28

actually, let's go there directly. it's not, um, a very obvious choice when you, when you pick from all the fancy stuff happening in fire. So how, how did you enter the path of, researching intumescent coatings? I don't think it's a very popular pathway.

Andrea Lucherini: 4:42

No it's not. Even though you can, if you're going into literature, if you can check like web science, there is a lot of research happening to that because it's a big. Topic and also is a the product is used worldwide, more or less everywhere. And it's a very, you know, modern way to protect, particularly everything started with steel structures, but is something that is spreading around the world and now is what's now applying to different materials. But in general, what are interes coatings? Interes coatings. It's a coating a paint, uh, which is usually applied in a very thin film that we discuss depending on the use, because usually we have two categories of interes coatings. We call it thin interes coatings or interes coatings. The thin interes coatings are the one that we usually use them for the so-called cell logic conditions. So it would be usually for the built environment where usually we. Something similar or the standard fire curve as a testing scenario

Wojciech Węgrzyński: 5:43

Okay,

Andrea Lucherini: 5:44

for the, far resistant test, we use that, far scenario to test the performance of that. So we, in, in the thin interes coatings, they're usually solvent based or water based, and they are usually applied in terms of a few millimeters. And, what is peculiar about, maybe I can explain later, but just to compare then we have the thick intermission coatings and the thick into medicine. Coatings instead are usually two parts. Quotings are usually for the majority epoxy based, so it's a more chunky, quoting that usually apply instead of millimeters, one order of magnitude higher. So in terms of thin centimeters,

Wojciech Węgrzyński: 6:20

Like a mass you would apply, not

Andrea Lucherini: 6:22

Yeah, it's a, it is a thicker coating and usually it's applied for conditions that are more demanding in terms of fire. So typically for the oil and gas industry for so-called either park carbon conditions is usually the market of these coatings.

Wojciech Węgrzyński: 6:38

Understood. And how did you end up researching this?

Andrea Lucherini: 6:42

Uh, yeah. So what happened, as I mentioned in 2015, uh, when I was at the end of my masters in, construction engineering at the DTU the Tech University of Denmark in Copenhagen, I was looking to different, uh, master thesis, you know, and, uh, you're like master student. You're excited and it is the first sort of experience in research. I was asking around about people that could potentially, professor, could potentially offer a master thesis topic, and I ended up in this extremely interesting topic related to international quotings promoted by Professor Grunds. And, uh, Professor Luisa Giuliani at the, dtu. So I picked it because I found extremely interesting also because it's extremely complicated problem and also extremely fascinating. But what I did, I did this five, six month research Based on the outcomes, I decided even to do my PhD based on that. Because what we did is, the first question we want, we were trying to answer is that if we have two coatings for the same application, so we took two random commercial coatings for indoor applications. for cellulose conditions, as I mentioned earlier, one was water based, one was so solvent based. We applied on typically, One section of a steel, uh, beam. It was an ip, um, beam, and we exposed to different fire conditions and were trying to understand how would this coating behave if we exposed to different conditions, typically different heating rates, but we also, we always achieve the same high tempera. So mainly we we did the most critical condition was the standard fire curve. So very high heating rates, reaching, 1100 degrees in about, uh, one hour. And then we did the same test using electric oven but achieving that 11, 1100 degrees in, you know, half an hour, two hours, and so on. So it was a different heating rate, but still the same temperature. And what we found extremely interesting is, The quoting since it was designed for some more or less, the same fire resistance class, so it would achieve the, behavior of the quoting under the standard condition would've been more or less the same, the two cases. But what happened between the two quotings? uh, the scenario of the fire resistance test would represent the worst of the best scenario in the two coat. Because what happened is that what you imagine if you have a fire, that it grows slower, That you would sort of have, allow longer time to de quoting, to swell. So it can sort of build a sort of more better, foam that will protect it. Um, while in the other case, if you have like a very fast growing fire, then potentially would create some sort of weakness in terms of cracking or parts that the touch and everything. But what we found out, one coating add the best performance in terms of we sort of calculate inversely uh, the firmer resistance or the effective therma conductivity of this. By, taking the, temperature of the protective steel, and we found out then in one case, the standard fire would represent the worst scenario, so would've the highest ther conductivity. Let's say. In the other case, the interes coating would represent the lowest FEMA conductivity. Therefore is a matter of how do we understand the performance of these coatings? Is it the standard five representing the worst case scenario or the best case scenario? Because as you know, I also discussed with

Wojciech Węgrzyński: 10:20

As if someone has engineered a product to pass a test. Huh?

Andrea: 10:24

no no not at all. Not at all.

Wojciech Węgrzyński: 10:26

We never said that. Okay. Okay, . Well, it is like that Anyway. to get to the bottom of, of why you've seen, uh, different performances in different condit. Because that, that's also what I hear from my colleagues at laboratory. That's why a slow heating, test was introduced because it's not, uh, secret knowledge anymore. It's, it's recognized knowledge that, that they will behave differently at different, conditions. So, to understand better why that happens, let, let's discuss how it works.

Andrea Lucherini: 10:58

So first of all, how will international coding. coatings I'm not a chemical engineer. I'm not a chemist. So what I usually take, I take the approach of a fire safety engineer or a structure of fire engineer that I take this magic formula I apply for my purpose keeping, for example, this, the temperature of, uh, protect of a steel column stay cooler than when it's unprotect. And then, take it and understand if does the job. That was my, the whole concept behind it. So what happens in the quoting itself? The quoting is made of different components, but usually you have three main components, which is an acid, an acid source. You have a carbon source, and then we have a blowing agent. So what happens typically, and now talking about, I did a bit of studies during my research experience. Now I've been working domestic quoting. For seven years, since 2015. So I've seen some INM coatings, but not all of them for sure. And uh, so around 200 degrees, let's say the acid starts sort of decomposing. and the coating where you can see the coating starts sort of melting or softening. So the viscosity of this distorting change. Then a certain temperature, usually 300 degrees or something like that. The blowing engine activates the blowing agent. What does releases, gases? These gases are released by the coating. And what happens since the coating is sort of melted or like a higher viscosity, what happens? The gas bubbles released by the blowing agent are trapped into this molten paint. So what happens is, Swelling by trapping these bubbles within its metrics. okay so this is at the base of it, and what happens is the quoting, something also I found during my PhD is, At the beginning, I didn't know how this work because what you see in a standard furnace test, you usually check the temperatures. Okay? A typically, you see this magic plateau that happens around 300, 350 degrees in your steel profile. And what happens is that decoding by that temperatures are mentioned, the blowing engine activates so the quoting starts swelling So what it does is start having a sort. We call it endothermic plateau, but it's not a proper endothermic reaction because endothermic reaction, it's usually, you know, a reaction that absorbs a lot of heat. But in this case, the reaction takes some heat and uses to make the coating swelling. And what this welding does brings the fire fire from whatever you want to. Then once you achieve these, temperature, the quoting start degrading. So it happens something similar to timber. So what you ever since is a high carbon. In the coating. So usually also this helps you in how it looks like as in color. Usually the coating, the classic one is white. Then when you're supposed to heat, becomes black. So it's a very high in carbon and there are certain points. Start again, becoming white and extremely brittle. What happens happens, the classic oxidation at the surface.

Wojciech Węgrzyński: 14:07

Hmm.

Andrea Lucherini: 14:07

Carbon is released, oxidizes is really through co2, but also carbon is what keeps the quoting together and therefore de quoting becomes, uh, you know, weaker. Some parts start the touching, But also as happens to timber, what happens? You have regression of the surface, So at the beginning it start as wells And then little beli start retracting as well.

Wojciech Węgrzyński: 14:29

Yeah. this is a very, very visual, um, description and I, I like how the mechanism works. Like if you have a, Heat transferred to a solid, you would have some sort of thermal conductivity, the difference of temperatures and, and the distance. And here, uh, of course you probably modified the thermal conductivity to some extent, but the distance is the part where you act. So suddenly instead of few millimeters of pain or, or coating, you have 20, 30, 50 millimeters of a foamed material with CAEs trapped inside, which are very good insulator that are the layer between you and the fire.

Andrea Lucherini: 15:02

So yeah, this is the tricky part of, you know, when you try to quantify, you know, the performance of interes coatings, because if you're trying to quantify the firm resistance, how it's defined, Thermal resistance is both, You have both thermal conductivity and thickness including to that, it's easy because you take a sort of bike, thermal resistance of thermal protecting property of the material to protect the substrate. Once you, instead you wanna define the thermal conductivity, then it becomes tricky because to define the the conductivity means you need to know the thickness all the time or otherwise. What people. Typically the methodology is also using the Euro code, um, for, e N 1 1 3 8, 1 part eight. So in, in one of the nex, you can quantify sort of implicitly effectively what is the conductivity by considering the initial thickness of the quoting. So you have this sort of fake ther conductivity because it takes into account everything that happens in the.

Wojciech Węgrzyński: 16:04

That's, uh, almost in particle physics, you cannot tell how quickly an election moves over where it is at the same time. You either can measure the thermal conductivity or the, or all the length, not, not bow at the same time. What's an interesting, twist? to, to solve, uh,

Andrea Lucherini: 16:18

I mean, this is what I did during my PhD, was one of my goals. I mean, what happens within domestic quotings the problem also, what fascinate me is that such a complicated, uh, topic because of all, you know, people usually associate into messing code. Active fire protection. Passive fire protection. I usually like to define it as a reactive fire protection because it's not unactive because you don't have to activate, like, you know, a fire extinguisher is not a passive that is a a board that stays there all the time. It's something that reacts a, since it reacts, we should consider that. You know, there are many aspects that could be affected that could affect the reaction and. And what I found also doing at the beginning of my PhD doing a bit of literature review, I found out that there is a lot of things that, influence, the domestic coding behavior. Uh, I can make some examples. Uh, I dunno if you're interested in mo, most of them I can talk about domestic coding as much as you want,

Wojciech Węgrzyński: 17:17

Worst case, I'll cut them out.

Andrea: 17:19

Yeah.

Andrea Lucherini: 17:20

I mean, first of all, it is, I'm not an expert, but first, main thing that influences the whole story is the composition. Is the composition. But this is something that I didn't dig into detail because I took, as I said earlier, the approach of a fire safe engineer structure fire engineer, take a product, understand does this quoting work or not? That's the question. question Then, Start looking at what are the variables that could affect Theas coating behavior. The first one is the classic one you discussed also far is the heating conditions. Heating conditions. That is also considered, as you know, overall fire conditions or testing conditions. Because you can apply, uh, heat flux that is pure radiant using a cone or RA panel. You can apply, mix of radiative and convective in a a standard furnace. but also one of the key aspects also influences as many other aspects in far safety engineering is oxygen content. What people have seen that, you know, in, for example, during my PhD I used some radio panels, so very high oxygen content around the coat. It's completely different situation than having a fairness when you have relatively low oxygen content within that. and for example, you know, if you have a low oxygen content, what I was discussing earlier about oxidation and char regression and what happens, you have a much lower, uh, phenomena if you have a low oxygen. then, so as I mentioned, heat test methods in general, but also heating conditions, fast growing, fire temperature, heat flexes, and things like that. Then another main importance is the thickness, and, uh, mainly how much coating you apply because sort of defines the mass and the quantity of your coating. Then you have the substrate conditions that I also look into that a bit during my PhD. . and also we can discuss this, it was another very hot topic of interes coatings is that, you know, we always test interes coatings when they are perfect virgin and just applied. But what happens since it's a reactive material, what happened to the reaction in a 5, 10, 20 years time? Because usually design buildings for, I dunno, a design life of 50. We need to make sure that that reaction at that material works also in a 50 years time.

Wojciech Węgrzyński: 19:35

In our lab, when we do the tests, we do this artificial, aging of the coating.

Andrea: 19:41

Mm-hmm.

Wojciech Węgrzyński: 19:41

Uh, by exposing it to different, uh, conditions, salt, radiation, tra violet, uh, water, and so on. So when they come, and the part that comes for, for the age testing doesn't look very white or or nice to, to be honest, but it is always a question like, to what extent this, this, uh, gives us A feeling of what happens. Actually, I, I'll tell you a funny story. it's not about paint, but more like the oxycodine that you've mentioned before. We had a client, um, they've purchased an old building in Warsaw, not super old, but let's say mid medium old, which had a steel structure protected by, uh, coatings. And, uh, they wanted to see, uh, what is how, how does it really look like, Is this, uh, steel structure underneath very healthy or unhealthy? What stage is it in? So they basically, um, went into the structures. Some parts, they just cut out with the steel. Some parts, they just open the hole in the coating just to change the, uh, what's the corrosion underneath. So they've opened like a hundred samples under. 30 or 40 year old still structure protected with that coating. And then they, they come to us and like, okay, and what do we do now? How are we supposed to fill the gaps we just made? Because the coating is not existent. We have a 30 year old material on the building, so you cannot just plump, a, a spec of, of very fresh coating inside and, and, uh, expect the exact same behavior. There is no paperwork that would allow it. It was like, okay, I shouldn't laugh at it, but it, ended up as being quite a hilarious issue because the, the, the steel was very healthy, , no damage at all. But now they ended up with, uh, with a structure with tons of holes in their fire protection.

Andrea Lucherini: 21:28

there is a bit of research related to that, that did the University of Naples in Italy, that they look into what happens. So they took like an existing structure they publish in construction building materials, very interesting research. And they look at how was reactive the quoting 30 years later. And what they saw is that, you know, the coating was not in the best state and you could never, you know, assume the same performance as a virgin quo. But also they showed that, you know, the quoting could be removed and reapplied, but also it could be also applied an additional layer on top of it and will still be

Andrea: 22:02

effective.

Wojciech Węgrzyński: 22:03

Okay, that's interesting. Like, uh, you have an old one. As long as you have adhesion for the new one, you can apply the new one.

Andrea: 22:10

exactly. Yeah.

Wojciech Węgrzyński: 22:12

but you, you cannot like just apply a giant amount of it because it is quite fragile. It, it, it will start falling. there's a reason why they tell you like what's the, the layer. It's not just the, about the minimum amount of, coding that you apply, but it's also in a way optimal because if you overshoot that, You will also, by force of gravity, it'll, it'll damage, to finish out the, the, um, chemistry and, and heat transfer part. So you've mentioned that at around 200 degrees, uh, there would be the action of the acs that, um, makes it softer so the bubbles can actually. alter the, material. Then at 300 s you would have the blowing material go on, but what happens if it hits up to 200 and just stops for an hour, like traveling fire

Andrea Lucherini: 22:57

Yeah this is, uh, you know, an interesting topic and, I did a bit of research during my PhD because I was interested about that and, uh, because at the back of that, we had some research that was carried out by my PhD supervisor or Chris Maluk at the the University of Edinborough, that what they saw is that having a, potentially a, let's call it a low growing fire or a preheating. In Certain coatings might create specific weakness into that. And uh, what they saw is that, for example, that, uh, the coating if it was exposed to slow heating, it would, uh, laminate. because what happens, you start melting it and then once is melted, the blowing agent and the gases cannot be trapped. So you sort of break

Andrea: 23:40

the. And

Andrea Lucherini: 23:41

a sort of process of, cooking off de coating. Like uh, when you cook something in your oven at the brown temperature, you know, and then for example, a cake doesn't grow, it works in the same concept. so I try to do a bit of tests and a bit of experiments even in life. It was like a qualitative and, uh, I was surprised because the quoting I used was working very well. Even if I cooked the, coating for about an hour at the heat flux that the would nots well was about 10 kilowatts. So usually it's like for low temperatures. Then the coating was keep swelling even after the preheating or pre-cooking face But this is again, what I found out is in, within my PhD I look into certain and a certain amount of my history, I've look into certain. product. Products are continuously optimized, created, commercialized that is very hard to keep up with all the coatings that are produced and sold in the world. This is one actually of the main shortcomings of my PhD that I mentioned I did. At the base of that, I took one quoting and I did experiments to understand the fundamental aspects of deco. But then the next step that has to be done is that to take the same concept and to see if this concept can be applied to also all the others, most likely for some, not for some, yes, but is tricky and challenging particularly because one of the problem we have with international coating research is that it's very hard and typically the name of the product are not closed. Because these magic formulations are usually hidden. And, manufacturers, they care a lot about protecting potentially their, you know, IP related to, the, the coating. And they can have, you know, good advertisement from successful tests. They can have bad advertisement, but usually you see, find a lot of tests, but usually you never know if they're connected to a product, another product or things like

Andrea: 25:43

like that.

Andrea Lucherini: 25:44

In a short, that's one of the hardest part of working in this field because you have, uh, you know, all these proprietary requirements that it's hard to compare or extend your study to other materials and,

Andrea: 25:57

uh,

Wojciech Węgrzyński: 25:58

when we talk about the behavior of steel or concrete, it's usually like you don't need very much to have quite well defined the material to have full reproducibility of the results in another laboratory when you talk about something, uh, so highly, uh, Protected, as you said, it's an i, there's a lot of chemistry inside, you know, so, so it's the IP of the manufacturer, of the paint, uh, or, or the coating, I guess It's these tiny details that, that might or break a certain application of the, of the coding. Like you, you've mentioned with early in your master thesis research where you had like to change the one water base, one solvent base outcome. So, so far from each other, uh, going forward with, uh, how this works in the buildings, I wondered what happens.

Andrea: 26:50

happens?

Wojciech Węgrzyński: 26:50

Swelling coating means an obstacle. Let's say there's a concrete beam or something next to a steel column that blocks it in a way so you cannot expand to the certain thickness or, or, or someone puts an obstacle,

Andrea Lucherini: 27:05

Yeah, I mean this is a super interesting topic and uh, we also did a bit of studies at the Uq, University of Queensland in Australia during my PhD, because we are completely asked about this. What I can tell you is that first of all, manufacturers usually suggest potentially a minimum distance at which any obstacle can be applied in front of, into mass quo. element. And tho that also this is related to, for example, the, if we discuss about fin and thick into mass coatings. Cause fin interes coatings uh, literature says that can swell up to a hundred times their original thickness. So from few millimeters they go to 10 20 cent. While thin intermission coatings, they usually as well, you know, 15, 20 times their. thickness. So what people usually suggest manufacture to avoid this problem is they suggest that at least the 50 diameters they have to be left free In the case of thin interes coatings or 10 20 diameters in the case of thick domestic

Andrea: 28:12

what

Andrea Lucherini: 28:13

actually happens is that at the base of all that, and what I found during my PhD is that, domestic coatings, Their amazing characteristics and amazing protective, performance is based on the swelling, is based on the concept of taking the fire away from the

Andrea: 28:28

the substrate.

Andrea Lucherini: 28:29

If you stop this dwelling, then you immediately have a

Andrea: 28:33

a weakness. And

Andrea Lucherini: 28:34

found this by doing some certain experiments at University of Queensland that we applied. sort of heat flux on the surface of the quoting. We used a mesh to sort of block the swelling, and we saw that mainly since the, also the obstacle heats up. so it also increases the conductive heat transfer for the coating then you you're ever, of course, a lower, performance. But then I also always wonder that. we should always, always think in engineer in terms in terms of if there is an obstacle, is gonna be the fire. Reaching the structure or the protected element because certain aspects can fall. You know, if you have a, a aluminum, uh, sheet on top in front of it, we know a aluminum would potentially melt at relatively low temperatures compared to, you know, a temperature where the steel structure can be So I think we have to also think a bit, you know, in engineering terms, solve the overall problem It potentially, you know, the obstacle can also block the fire, not just

Andrea: 29:32

just as well.

Wojciech Węgrzyński: 29:33

it will also shield from ation in a way. It's, uh, it's a way more complicated, manner than just, it's present, but does the swelling, um, Like, is there a force in this swelling? I dunno how to precisely tell it. Like can it push an object away if I put a bottle of water next to a wall and it's

Andrea Lucherini: 29:52

like What I can tell you is that if we discuss about big numbers it's like feeding domestic coatings are applied in terms of millimeters Okay? So few millimeters about you know, depends on the coating, but 40, 50%, 60% are potentially made of volatile. are this blowing agent that will blow the gases. And so we discuss about densities. when, of this, wild coating of about 50, a hundred kilos per cubic meter. So it's not anything tough or robust that is pushing things away. No. The quoting is very fragile when actually ass

Andrea: 30:32

swells, and actually

Andrea Lucherini: 30:34

actually when it's oxidized, it's

Andrea: 30:35

even weaker.

Andrea Lucherini: 30:36

So sometime you can just

Andrea: 30:38

blow it and it

Wojciech Węgrzyński: 30:39

that, that, that was where I was going with it. to what extent it's fragile in a real case of fire, like next to a fire plume, you can have seven, eight meters per second of airflow just because of the convective action. But I see them being used like near jet fans in car parks. Jet fund outlet 20 meters per second. Hmm. That's, that's a lot. And it looks fragile to me if I, if I look at it. I wondered, have you ever observed in your research, like, in a way, mechanical failure of, of a coating like being blown away from the protected element?

Andrea Lucherini: 31:11

I mean, what happens in in furnace, usually you don't have requirements in, you know, velocities. So it is something that you sort of implicitly see. Because when you open the furnace at the end of the test, you see some parts of the coating that are detached on the floor. You were even, like, sucked away from, uh,

Andrea: 31:29

uh, the exhaust.

Andrea Lucherini: 31:30

But an interesting study that I studied during my PhD was a study that I did in 2016 at the Rise, and there was, um, Robert Johnson

Andrea: 31:40

and McNair

Andrea Lucherini: 31:41

uh, that they sort of did a sort of bench skill test and they created some sort of, jet flame scenario and they expose some coatings, to, uh, far scenario and the so that, yeah, the quoting would touch pretty easily. so it's definitely a weakness. How to quantify what's the stent of this weakness is something that is, uh, extremely complicated and, uh, I

Andrea: 32:04

I haven't investigated during my.

Wojciech Węgrzyński: 32:06

Now what comes to my mind that there are interes materials would also be often used for cavity barriers, Ceiling in facades and in in, a cavity of facade you can have fairly high, um,

Andrea: 32:18

It's

Wojciech Węgrzyński: 32:18

of air just because of the, the convective airstream. Wow, this is, this is going well, . I, I, I love the world of magical paint to be Okay, let's, let's go further. Uh, next thing on my list, you, you mentioned you were testing them in a furnaces. You were using h TRIS uh, I guesses, which is, uh, a radiant panel in front of, of this. These are fairly small, uh, scale, uh, test, units. Do you have an experience with the behavior of this in, uh, like a full scale in like a compartment setting? I guess there are also like real case fires where this where this worked. Basically, if it didn't work in the real fires, we would know already, I guess.

Andrea Lucherini: 33:05

Yeah. Okay. First of all, during my PhD, I tested in a bench scale set up because what I started as the idea is that I mentioned earlier that domestic coding behavior is affected by many different aspects. what I wanted to do, I wanted to take Quoting apply on a very well defined thermo boundary conditions, both at the surface but also the substrate, and to see as soon as I change certain aspects, how their quoting behave. So what I found out is that I was using, mainly using steel plates coated with different, thicknesses of interes coating, and I was changing the thermo boundary conditioner surface, the far scenario, and also the thermo boundary conditions at

Andrea: 33:47

the subs.

Wojciech Węgrzyński: 33:48

Mm-hmm.

, Andrea Lucherini: 33:49

I found out that first of all, their far scenario, the heating condition, what they control, they control the dwelling rate and also the dwelling rate means how fast this coatings wells. But also, I also found out, and I try to define which are the condition to make the quotings. Because there are some conditions that you know, below a certain temperature or below a certain heat flux. the quoting does as well. And I call it, I have a study and a paper related to that focus on onset as swelling of interes coatings. Then I was looking at the thickness of the, the initial thickness of the quoting and what I found out, if you fix the thermal boundary condition the heating condition of the quoting, what the thickness. Evaluate how much the quoting can, Well, potentially. Well, because this is a sort of like, you know, mass balance, you have a certain amount of mass. The quoting can, well, a certain amount. Therefore the, I found that with a linear relationship within the range of the tested, that the maximums weld quoting thickness can be related to the initial.

Andrea: 34:53

Okay.

Andrea Lucherini: 34:54

And then also I did the last aspect about the thermal boundary condition, the substrate, because this came out and we can discuss later that now into messing coatings, they are pushed to be applied also to other, not just steel, but also other substrate materials, timber, concrete, things like that. What happens you change by changing the material. You change the thermal properties of how this material would behave, particularly would behave close to the surface of the mater. Therefore where the coating seats and where the coatings Well,

Andrea: 35:24

Well

Andrea Lucherini: 35:24

and what I found out that we can discuss in the case of high insulated material so heat doesn't penetrate through the material, then the coatings wells much faster because mainly all the heat is concentrated at a coating and this is the case, for example, of timber. Then if you have the case of a fixed steel plate, that this is a. lumped the heat because still as a high thermal inertia, so it has to heat up gradually, so therefore this violin behaves slower. Then if you have something we, we did, I did a study on a, on a heat sink. So there was a, a steel plate and at the back. I had a sort of radiator system. There was a steel plate that there was cooled with uh, water and it was taking heat away the other side and what I found. The quoting, all the heat I was receiving, the quoting was actually leaving the quoting because it was, there was like a, you know, it's a sort of energy balance at the quoting is the energy come that comes from the fire and the energy that leads from the substrate. So you have to do an energy balance of that and you can understand how the quotings

Andrea: 36:29

well.

Wojciech Węgrzyński: 36:30

Oh man. I find, Biot number, annoying enough as it is, and if you add now, uh, to the problem, the, the fact that your dimension changes with time as this progresses and your Biot number most likely changes as well as it progresses. Oh boy, that's, um, the complexity of fire.

Andrea Lucherini: 36:49

So that's that was a mention that all the different aspect that, changes it and this is the case of, one D heat transfer is a plate with a hot surface on one side and some sort of thermo band conditions, a substrate. Then going back to your question. What happens in large scale? In the large scale, you have another bunch of effect, uh, phenomena. Not just to mention, you know, in a compartment five, you might have convected gases, so you might

Andrea: 37:15

might have speeds.

Andrea Lucherini: 37:17

I mentioned about different level of oxygens, but also another aspects that the found is also some research related to that is the shape of the substrate. Because what you can imagine, if you have a concave or a

Andrea: 37:30

a convex angle

Andrea Lucherini: 37:31

with the coat, Then you can have, you know, in a concave angle, you have a much more coating than the surface

Andrea: 37:37

to protect.

Andrea Lucherini: 37:39

Therefore they have a much more coating and that angle will be nicely protected. Instead, if you have, for example, the top or the bottom fla

Andrea: 37:48

on a

Andrea Lucherini: 37:49

beam is a sort of very, rough, uh, acute angle. Then in that case you have very little coating, but a very big surface to. It's

Andrea: 38:00

geometry, you know?

Wojciech Węgrzyński: 38:01

Must be fun for, for circular, like, circular beam, uh, pipe. Sorry.

Andrea Lucherini: 38:05

yeah that's also in circular pipes, it's a bit more homogenous geometry, so it's a sort of swells altogether. But when you have these sort of very sharp angles, then you might have, a sort of thermal bridge then heat can penetrate through that. So is, is such a complicated topic.

Wojciech Węgrzyński: 38:22

Hmm.

Andrea Lucherini: 38:23

try to solve one aspect and then you forgot another

Wojciech Węgrzyński: 38:27

However, The definition of failure is not, is also not very sharp in here. Like I guess by experience you can have some of this fail, some of this not swell perfectly, and yet still achieve the expected performance, from the larger point of view. That that's what I've been told in the laboratory, that you have like a certain amount of measurement points, you average them. There's a criteria for some of them, You don't need, uh, the most perfect uniform action on all of the surfaces all at the same time to achieve the benefit of, of the fire protection, right? This is how they're designing in minds, right?

Andrea Lucherini: 39:04

this the framework we have now. We have some strength, but also we have serious weaknesses because you know, still for if we apply interes coatings to protect a steel column, that would've, you know, free for exposure to a fire. Having a large scale experiment is. That must represent this scenario because in the end, for structural engineering purposes, you wanna keep the temperature of the steel low or below a certain critical temperature, whatever is defined. The important is also something that Piotr lightness in this, uh, episode is, are we. Aware that certain key parameters of the this framework can strongly affect the performance of these materials? What Piotr mentioned that at the beginning, in the first 10 minutes of the standard furnace test, anything can happen, and in that period of time is when the quoting

Andrea: 40:02

swell.

Andrea Lucherini: 40:03

For example, the quoting has been designed to have to be very reactive to a very fast thermal shock. The classic, very fast growing fire of a very fast growing fire or standard temperature time curve. So it works very well in that scenario. So maybe an international manufacturer would prefer to have a, you know, a very big push in the temperature at the beginning because the sort of activates. Foster the reactivity and the, the performance of this quoting. But then you know, that thermal boundary condition controls the whole

Andrea: 40:34

whole story.

Wojciech Węgrzyński: 40:34

I would say what makes the pain, the coating, uh, really work in fire. I mean, once it swells, it's basically down to Forueir problem. Heat transfer problem. If it has this depth and this thermal conductivity, it'll achieve this performance. It's simple physics if the, the thermal boundary condition is known. So from 10th minute of the test, you basically, like, you could stop the test at that point because if you know the external temperature and basic, parameters of the perfectly swollen, coat. It's a heat transfer problem, but what, what makes it or breaks it? Like does this achieve this level of swelling in the first minutes? was it capable of reaching this point where it's activated?

Andrea Lucherini: 41:20

The process of swelling takes time, and it's not something, particularly the more coating you put the thicker thickness, the longer it's gonna take. Then how long does it take when you start degrading the quoting and everything? That is something that depends the test by test. But for me is that since at the base of everything, the motivation of my research is that we assume that the scenario we're testing so fast, grow. Very high temperature. Fire is the most critical scenario for a

Andrea: 41:51

a structure,

Andrea Lucherini: 41:52

but is it the most critical scenario for the performance of an interm coating? That's another story.

Wojciech Węgrzyński: 41:58

Yeah,

Andrea Lucherini: 41:59

And uh, and as you know, as we discussed, chemical engineers, manufacturers there are smart enough to optimize their products for all the scenario that are required to be. So it's, it's not a viable anymore. They take, that the fire scenario is defined and then they have to play with all the rest. They can look at, you know,

Andrea: 42:19

know,

Andrea Lucherini: 42:20

char strength swelling

Andrea: 42:22

rate

Andrea Lucherini: 42:23

so it is, an extremely complicated topic and very

Andrea: 42:26

challenging to work with that

Wojciech Węgrzyński: 42:27

We're entering dangerous grounds. I must stop you there . I like my knees like they are on shot , so Yeah. But yeah, you, you are correct. that's the battle we have like optimizing for test standard and not understanding the, performance in the, in the real building. And there is nothing like standards are used to rank materials, to classify materials, to safely put materials on the market to assure that materials do have a, characteristics they claim to have. It's, Very important part and, and something that worked very well for the last hundred years in, in providing safety for people, for masses. The practical performance is something else. Right.

Andrea Lucherini: 43:09

what I can say is that there is a bit of movement into these because with a big push of performance

Andrea: 43:16

based design,

Andrea Lucherini: 43:17

you know, the big assumption that usually fire safety engineers do is that they assume the performance of any intumescent coating in any other scenario. Which is the biggest assumption and most dangerous one for me. But now there is a bit of push in having a better and deeper understanding on how this material would behaves in different

Andrea: 43:35

conditions.

Andrea Lucherini: 43:35

And, uh, manufacturers are aware. also I think there should be something I've been trying to push with my research, try to push for more understanding and more conditions to understand if this quoting would behave in the dangerous situations or the for structure. And there are some manufacturer that are pushing for this change and are pushing for optimizing the product not only for one condition, but also

Andrea: 44:00

others.

Andrea Lucherini: 44:01

and they should get credit for that because they produce a product which is reliable. And since it's also intumescent coatings are expensive product for when you consider the different fire protection of various structures. So it's something that we should, uh, reward for people that trying to really understand if, uh, the product is

Andrea: 44:22

robust.

Wojciech Węgrzyński: 44:23

Absolutely Amen to that a hundred percent. Okay. So, we are, um, nearing the end of the episode, but I, I really wanted to ask you about, your future. Plans. But, uh, there, there's a question for insent pains that, that really connects to that very well. Like to what extent we can protect, like timber with this type of solutions. I saw that, uh, happening lately. It was very interesting to me.

Andrea Lucherini: 44:48

I mean the, the concept is, Of course it can. We have to make sure, and we saw already application, it's not just concrete, it's not just a timber, but people have been also applying to machine coatings on concrete to improve, for example, to reduce the temperature within, uh, the rebars in concrete, for example, in, you know, historical buildings where you cannot change the section of an element, but you have to increase the fire protection. So you just apply a fin coating. You get like the class that you're required to improve but also to mitigate spalling. Sometimes we have been seeing like some research

Andrea: 45:24

that has been used for

Andrea Lucherini: 45:26

purpose. For Timba, the story is slightly different because uh I seen, and I worked also during my PhD on successful products international coatings applied on timber. And there are certain aspects to consider. First of all is the de between the two subs. So for some aspects, the coating might be much, I have a much better addition to the substrate because what happens, timber is hydroscopic so what happens absorbs, what is the surface? So some part of the quoting can be absorbed within the matrix of the timber, the surface, and also in, and therefore ensure

Andrea: 46:03

adhesion at the surface

Wojciech Węgrzyński: 46:04

Is that a good thing or a bad thing?

Andrea: 46:06

is a good.

Wojciech Węgrzyński: 46:07

Okay.

Andrea Lucherini: 46:07

Because it gets, and you have

Andrea: 46:09

have a better

Andrea Lucherini: 46:09

addition. Then the other aspects is The difference between critical temperatures, let's go like that in the two substrates, steel and timber, still the you know, you have critical temperatures above, you know, five, 600 degrees, but then the substrate stays more or less in the same way during, uh, the fire timber. What happens? Around, you know, 200, 300 degrees, the paralysis and charing process starts. So what you could have and what I mentioned earlier, into messing quotings, they typically, well for temperature for 300, 400 degrees. So what you see is that when the quoting starts welling, the surface of the team start

Andrea: 46:46

start charring as well.

Andrea Lucherini: 46:48

And this could be tricky for the addition not of the quoting on the timber, but the addition of the

Andrea: 46:53

of the char on the.

Andrea Lucherini: 46:55

But then again, if the coating starts welling, you have your Deion, what Mainly you have, you have, again, a bit endothermic process that mainly plateaus the surface. And what happens if you make sure that the coating is stays at the surface? You can mainly postpone the onset of swelling because you have like a delay. Plus if the quoting stays there, you have something that protects. So potentially the charter rate of the timber can be also.

Wojciech Węgrzyński: 47:22

That's, uh, that's so complicated.

Andrea: 47:24

amazing

Andrea Lucherini: 47:25

In theory sounds amazing, in theory. Sounds amazing In practice, we need to see experiments and tests better to that.

Wojciech Węgrzyński: 47:32

I find it like we're living in two different worlds in one painting A Surface. Such an easy task, and it's such an easy solution. It just, Painted, like, do the primer, do the colting, do the external layer. You're done. Uh, the bucket says it's 60 minutes, you're very happy. But the chemistry, the physics that goes inside the, the beautiful complication of a heat transfer that is suddenly changing in time and space at the same time.

Andrea: 47:58

mm-hmm.

Wojciech Węgrzyński: 47:59

I understand why this, uh, subject was so attractive to you because it's such a complicated manner and, uh, very, very interesting one.

Andrea Lucherini: 48:09

Just last thing I wanted to mention is that, what I try to do during my PhD, during my research is that to understand what are the fundamental factor that affect these, the behavior, these materials, because only in that way we can design

Andrea: 48:23

a test,

Andrea Lucherini: 48:24

uh, no experiment, whatever you wanna call it, that allows us to understand if the product will do the

Andrea: 48:32

the purpose.

Andrea Lucherini: 48:33

That what we have to, and we don't know at the

Andrea: 48:34

the moment. Unfortunately,

Andrea Lucherini: 48:36

we spend a lot of money,

Andrea: 48:37

but, uh, we don't know

Wojciech Węgrzyński: 48:38

Well, we know a bit more. You've successfully, uh, made modeling attempts. You've described many of the phenomena in there. So certainly thanks to your, And they, we are much richer in knowledge in this regard. I will definitely link all I found, uh, with your name on it about inter pains in the show notes.

Andrea Lucherini: 48:58

things.

Wojciech Węgrzyński: 48:58

And, uh, yeah. Andrea, thank, thank you very much. Uh, brilliant. Ya a scientist, developing So quickly. Watch this space, guys. uh, this space is good. It's interesting to see, see you grow and see your, uh, future findings.

Andrea Lucherini: 49:14

Thank you very much Wojciech was my pleasure to be here particularly. After the big names that, uh, I've been listening and, that I've been ad admiring and study from over the last, uh, you know, 10 years of, uh, fire safety engineering. So

Andrea: 49:28

my pleasure.

Wojciech Węgrzyński: 49:28

Thank you very much and, and see you around. Cheers, man.

Andrea: 49:31

Cheers.

Wojciech Wegrzynski: 49:33

And that's it. Thank you for listening. Hope you've enjoyed this conversation. There are things that I wanted to cover, but we haven't had the chance to touch them. One being modeling. To muslin. Coatings says very interesting subject that Andrea has actually done in his PhD. It's it's lingered in the papers on the shownotes of the episode. It wants to read about it. But it's something definitely that could be covered on the podcast episode. So maybe a topic for a future ads. One thing we didn't touch is debunking myths of. Some magical pains that are on the market. Actually that call is for a podcast episode on its own as well. On the way, precisely these magical beans that withstand. The little blowers. Like heroes. Do those really provide you? Good protection against through the fires in the world. Wow. Hopefully that will be covered one day and I'm very. Maybe, maybe for some sort of celebrate every episode, that would be a topic I would enjoy demolishing on. So Certainly something for the future. Anyway, thank you, Andrea, for coming through the forest and show, it was a pleasure to have you. Thank you all for listening to this podcast. If you have something to share about intimacy and coatings, or if you want me to cover some other aspects of the subject brought in here. Or maybe bring more fire safety engineering. In terms of solutions applied to, to provide safety in buildings. Let me know in the comments, So I know. Well, Daya topics excites you most and looking at. Uh, just the raw numbers. It's not always the best indicator of what's being popular in here. However, I think you may enjoy. Those that cover technologies because that's something we always And not only philosophical or very Ivory tower and topics, but down to earth engineering and why stuff works. And when it stops, I think that's fundamental to understand. As a fire safety engineer. So thank you for being here and next week. Well, actually next week, there's going to super exciting sprint. Uh, topic notes, very practical today, but absolutely exciting for any fire safety engineer. I'm not going to spoil you. You're going to see next Wednesday. So. I See there by