Summary

An intumescent coating can be qualified or disqualified for use simply because it falls above or below a certain magical hardness level, usually as measured on the Shore D scale. But hardness has no influence on performance, and the Shore D scale just doesn’t make sense when assessing softer intumescent technology types. Fireproofing industry veteran Michael Hollman explains the consequences of misusing Shore D hardness in intumescent coating specifications.

Also, Michael worries that his brother-in-law might soon beat him at snooker.

Timestamps

Click to follow along with the transcript:

• 00:00 - Introduction
• 03:01 - How the industry's understanding of hardness has evolved
• 05:55 - Durometers' importance in measuring coating hardness
• 07:31 - Matching different Shore scales to different coating technologies
• 09:39 - When standards are "cut-and-pasted" without context
  
• 13:34 - Harder is not universally better
• 18:15 - Elasticity, damage resistance, and impact recovery
• 21:12 - Viewing Shore values as a reference point, not a product differentiator
• 22:40 - The four questions

Transcript

Introduction

Toby Wall: The cured hardness of an intumescent coating is important for a variety of reasons depending on where you sit in the contract chain. Rigid specifications often force construction teams into choosing among only a few materials based on their hardness, usually as determined using the Shore D scale. As we'll discuss in this episode that's a problem. My colleague Michael Hollman joins me to talk through how to solve it.

Well Michael, thanks for joining us on The Red Bucket today. If you wouldn't mind, before we get started, maybe give us the brief biography. How did you get to where you are today?

Michael Hollman: Good question. So, straight out of school, I joined the local paint company as a junior technician in R&D, and I was selected to work in the fire protection lab.

And actually, that's all I've ever done since then. So, I've had thirty-two years in the industry working in R&D developing intumescent fireproof coatings of all different types of different companies, as well most of the market-leading companies, testing and supporting those products into many different countries around the world through the local fire testing standards that are needed for each of those countries.

So yeah, it's been quite an interesting career. It's taken me to many different countries and continents and meet some interesting people. So that has brought me to RPM and Carboline, where my current position is global product manager, looking after the intumescent fireproofing range, responsible for developing a pipeline of products that meets our current and future needs for the different markets that we want to operate in.

Toby: Speaking of all these different countries and continents that you've been to, the country that you are in, if guests didn't already notice your accent, you are where sir?

Michael: I am English, and I am currently in the miserable north of England, very close to Manchester. It's a great place. It's just the weather is a bit miserable today.

Toby: We are recording in the middle of February, where the difference between the weather Michael's having today and the weather that I am supposed to have here in Saint Louis is, I don't know if you could, you couldn't draw it up any different than what we'll have.

How the industry's understanding of hardness has evolved

Toby: So, there's one big idea with this whole episode, Michael, regarding hardness of intumescent materials. What's the big idea?

Michael: So, the idea is the Shore D hardness of an intumescent material or coating has zero influence on its performance.

Toby: I guess we can stop right there. Thanks for joining The Red Bucket, and we'll be back next time with another great guest.

So, what do we mean by hardness, for those who might not be familiar with you know what it is or why, in this context, that it matters?

Michael: So, what we mean by this, the hardness, is typically the extent of cure or drying of a coating. So, it's a physical measure that we can look against and have an absolute number that will actually tell us when the coating is either chemically reacted or physically dried to the level that is not going to progress any further beyond that.

Toby: Has measuring its hardness always been the way that we understood how well cured or how finished a coating is?

Michael: No, it hasn't. So, this is where it is always been common practice in the hydrocarbon industry, where you've got thick epoxy coatings and its part A and part B are mixed, and you can measure the hardness as an indication of when it's fully reacted and then it's ready to be put into service.

But what we are seeing now is that it's actually going beyond that market and that technology, and it's just becoming a blanket term now for use with all intumescent coatings, regardless of the technology or the market, really.

Toby: So, you've seen that gradual adoption over your 32 years then, or does that pre-date your entry to the business?

Michael: Over the time that I've been in the industry, in the early years it was limited to one particular area, but then we have seen more and more where it has gotten adopted in other markets where it's not really relevant. So, as I said earlier that it has typically been used where these epoxies in part A and part B are mixed, and it indicates when the reaction is complete, or as complete as it's going to get.

But now what we are seeing is it's used in more architectural coatings, whereas a single-part coating that just lacquer dry. And because it is different technology, to use the same scale and the same expectations just aren't appropriate.

Durometers' importance in measuring coating hardness

Toby: Those numbers, those measures, need to come from somewhere, so there's of course specialty equipment that we use to find that out. Can you tell us what a durometer is? How would you describe that?

Michael: So, I would describe a durometer as a simple handheld tool that has got a needle of different types loaded onto a spring, and then the spring is connected to a dial.

So, that would be an analog one. Obviously we can get digital ones now in today's technology, but an analog is the simplest and most common one. And then you simply press the needle into the coating until the foot is flat. And then the resistance on the spring will force the dial around and give you a number.

This is because needles are very different dependent upon which type of durometer gauge that you're using, the needle will indent to different degrees. So, what we see with very hard coatings, then you use a needle that is extremely sharp. But then with softer coatings, and this is going to be all the materials as well but it is typically used with coatings, then the needle has got more of a rounded end to it, a bit more of a pinned finish rather than a sharp needle point.

Matching different Shore scales to different coating technologies

Toby: There are more than one hardness scales. You mentioned Shore D at the beginning. There are, at least from my reading, there are 12 different scales, and for this discussion we care about two of them, Shore A and Shore D. You mentioned the shape of the foot. Which hardness scale gets which shape of the foot? Which one is pointed and which one is blunted?

Michael: Okay so Shore D is the fine needle and Shore D is used for typically hard materials, very tough materials. And Shore A is a rounded needle, it's not really fair to say it's a needle, really, but it would be like the end of a knitting needle or something like that, so it's got quite a soft rounder tip, and this is used for softer coatings.

Well as you said, there are a lot of others as well, and if you look at the standard, which is ASTM D2240, it will describe the typical coatings that are used or typical materials that can be used and can be tested with each of the different durometers.

Toby: Does that standard, among the different coating examples that it states, does it state intumescents as one of the ones? And if it does, which scale does it tend to put it in?

Michael: No, it doesn't state intumescents. It will just give typical types of products. So, coatings would be in that, of which intumescent would be a subgroup of them. But then there are others where it will typically say foams for measuring the hardness of things, like foams for comparing one against another. Then that is a different particular grade of durometer.

When standards are "cut-and-pasted" without context

Toby: How well do you think this topic, the hardness scales, Shore D, Shore A, how well recognized are these in the minds of the folks interested in intumescents, realizing that you know depending on someone's job they're going to have a different level of awareness?

Michael: I don't think that they are very well understood - that there are differences in the scales. So, I think that we have seen some initial specifications that typically were for offshore for determining when a coating is ready to go into service that have been cut and pasted, essentially, into other markets, other projects, other construction types without the recognition or understanding that maybe that particular part of the specification just isn't relevant to the project or the coatings that are going to be used for the fire protection solution.

Toby: Which brings us back to the reason why the Shore D scale is the one that I guess is found the most often in this world and the world of intumescents because it was borrowed from somewhere else.

Michael: I think that's a perfect way of boiling that down, Toby. I think that it was done for an industry that is highly specified with the offshore Oil & Gas petrochemical industry, and then as the specifications have advanced for different markets, then it's been borrowed without actually checking if it's appropriate and modifying accordingly.

Harder is not universally better

Toby: Owners, architects, engineers understand Shore D and understand hardness a little bit differently than a contractor would in the shop or in the field.

Michael: The owners, architects, it's seen as a way of determining that that product is fit-for-purpose and would be okay in service. So, it is hard, it's tough, it's going to be okay for the lifetime of the building.

I think for the contractors and things like that, I think we could argue whether it's actually just a tick box exercise, that it's on the specification so it doesn't actually mean that much to them and you know they just got to comply with it.

It might be it's seen as a way to differentiate between different products, how good they will be in transporting so that they're not prone to damage. But ultimately, even if coatings are softer, then we can employ best practices for transporting as well.

Because I think that we have two sides to the coin. Generally, hard coatings can be quite brittle, and if there is any damage, then that damage is exacerbated around the area where if there's things like an impact. Whereas if there are softer more bland coatings, then actually these can absorb any damages more easily and readily and will be more suitable for transporting.

And it's trying to get this across to the contractors that actually: just because its higher number doesn't mean that it's actually better for any damage resistance or impact resistance.

Elasticity, damage resistance, and impact recovery

Toby: I want to talk about recovery. Does that refer to a material can bounce back and take its original shape after it's been compressed somehow, or like say it's been hoisted up by straps or on a forklift or something?

Michael: Yeah, that's exactly it. So, it's the elasticity in a coating rather than just simply being displaced in the example that you give about hoisted with straps on a forklift truck. With some coatings it might be that it simply squashed out from underneath those straps by the weight of whatever is being lifted. Recovery would be the elasticity to be able to jump back into the original shape or form.

Toby: Does that matter in terms of reaction to fire? Let's say if something is smushed down and doesn't recover, is that somehow limit its ability to do what it is supposed to do?

Michael: I think it can do if it's smushed down to an extent to where there is insufficient cover on that particular part, because the intumescent fire protection is tested and certified in a way that for that particular piece of steel, a certain thickness of coating is needed for a specific time of fire protection.

If the coating is deformed in any way, shape, or form, if you've got under coverage in that area, then you might not necessarily have the required and necessary amount of protection in place.

Toby: And so, we have the, you know material technology has advanced to the point where we have these, these products out there that do recover better than others. It makes me wonder if there's a level of forgiveness there. Not saying that you shouldn't take care when you're transporting your materials or transporting your steel but it's an extra level of assurance maybe?

Michael: Yeah I think so, and this is where we would highlight this as damage resistance, because what we do see with coatings that are very hard or that have a high number on the Shore D scale could be quite brittle.

So, if there is an impact, then it can spread wider than just the impact zone, so it might delaminate, for example. Whereas if we have coatings that are a bit more elastomeric and do give a little to the weight and the pressure, then any damages is minimized or even eliminated.

Viewing Shore values as a reference point, not a product differentiator

Toby: Let's say we have an opportunity to just wave a magic wand and change what specs say or maybe go beyond that and also change what people know or what people understand. But what is the, what do you think is the proper, at least as far as documentation goes? Are we saying Shore A and Shore D should exist side by side? Are we saying that these shouldn't be there at all? How do we, how do we reconcile?

Michael: I think they should exist side by side. I don't think that they should be used on specifications to differentiate between one product or another. I think that they should be used for quality purposes so that we know exactly when the coatings have reached ultimate hardness or cure level or drying, whatever we want to term that.

But then those numbers are specific to the product that has been selected. And I think the products should be selected on other things, as you mentioned earlier, like the ease of application, the fire certification that it has, all those other properties, but not necessarily hardness.

The four questions

Toby: We have 4 very important questions now that we get to ask Michael because it's The Red Bucket, and The Red Bucket always has 4 questions at the end. So, what is the most interesting job site you've ever visited? And in 32 years I'm sure you've seen quite a number of them.

Michael: Good question, I think the most interesting one, I think, was where we had a complaint actually that our coating was blistering on application. And we put several different possibilities to the customer, one being that they had applied to much thinner to the coating and it was skinning over the surface and the thinner was being trapped inside and blistering.

And they denied everything and insisted on a site visit. So, this involved a four-hour flight and then a three-hour drive to get there, and within the first five minutes we identified that they had just thrown in a huge amount of thinners into the coating and completely destroyed the product. So that was a really long day and trip to really fix something that could have been identified over a Zoom call or something.

Toby: That's like those meetings you have at work, and then you leave it thinking, "that could have been an email, this would have been fine if it was an email."

Michael: Yep, exactly.

Toby: Where's the best vacation destination that you've ever been to?

Michael: That's a very good question, Toby. I like the Greek island of Rhodes and also Istanbul in Turkey because there is just a lot of history to go and see there. But I also like Asia as well, and it's just excellent food, really friendly people, and lots to do and see.

Toby: So where do you recommend?

Michael: Istanbul. I would recommend there's just so much history to go and see.

Toby: How about in Asia?

Michael: In Asia there's no bad places, I think. I like Hong Kong, Singapore, if you've got plenty of money, Vietnam if you don't have plenty of money, but also Thailand is really nice and Malaysia as well.

Toby: You got a favorite hobby?

Michael: Snooker, I play snooker. So, me and my brother-in-law play quite regularly, and he's getting a bit better, so I'm running the risk of he might actually beat me at some point, so I need to up my game.

Toby: Go hit his hand with a hammer or something.

Michael: Exactly.

Toby: Tell us Americans what snooker is.

Michael: So, snooker is, I guess, a little bit like pool or billiards, but the table is a lot bigger. So, it's 12ft by 6ft and the balls are smaller and then you have 15 red balls and 6 colors, and you have to pot them in order.

So, it's a red color, red color, red color and then the colors keep coming back out until there's only the colors left on the table at the end. And you have to pot those in sequence.

So, the maximum that you can get is 147, and the most I've ever had is 57, so I'm nowhere near the maximum.

But the world championships is in May, and there's one guy that's been best in the world for a helluva long time, and he holds the record for clearing all those balls in under 6 minutes, and no one has ever come close to that again.

Toby: I was thinking, as you were describing how it goes, a game must take a long time.

Michael: It can be. It depends on who you're playing and also just how you playing as well. So, you know, I've played for a few teams, and I think I'm not a bad player, but when I've had a game, a match game against one guy in particular, I remember I was in good form, he was in excellent form, and we finished the whole game in less than 8 minutes.

Toby: Oh wow.

Michael: But then I have been involved in some real long ones where you're talking an hour and a half.

Toby: I was going to say, I've never played it, and I feel like if I did, I'd have to bring a sandwich with me because we'd be playing that long.

Final question, Michael. As an Englishman who has been to the States, it was nice to see you when you were here the last time, by the way, what is the best American food you've had and what's the worst American food you've had?

Michael: I think the best, I like gumbo and jambalaya, so those would be a couple of my favorites. And I think the worse one is deep fried pickles. I just don't understand that.

Toby: Oh, I had some for the, when the Superbowl was on just last week. We had some fried pickles. I don't know if I, I'm not going to go so far as to disagree with you and say that actually they're great, because I don't think they're great, but I think maybe that's just the yank in me. Like we'll throw it in some hot oil, and just no matter what it is, I guess in our minds we think that's okay because we'll do that to like ice cream and cookies too, which I don't get that.

Michael: Yeah, we have that in UK particularly, in Scotland as well, where they will deep fry anything. So, pizza, they will dip it in batter then deep fry it. Pizza, a Snickers bar, things like that, so it's quite famous, but then again the mortality rate is a lot lower in Scotland than it is anywhere else.

Toby: Hey, I guess they've got something figured out.

Michael: Yeah, I appreciate it, I enjoyed it.