Epoxy School Blog

Epoxy opinion - what makes an epoxy expert?

Time for a bit of light-hearted thinking on the topic of experts in this serious world of epoxies.

I guess there are a lot of definitions for an expert, but, in a real sense, who and what are they? Why do so many people try so hard to act like an expert? Why do they like boasting about having the same opinion as an expert? I've never really understood what all the fuss is about to tell you the truth.

Why do we think experts are so important?

The classic Oxford dictionary defines an expert as “highly practiced and skilful or well-informed in subject.” Well, there’s no doubt some people can legitimately claim to be that, however the coating industry is unfortunately littered with wannabes. Why? In my opinion, it seems people need to either satisfy their ego or justify their job title. Others pretend because they’d like to help, which is admirable in a way, but only end up making things worse.

On the other side of the coin, some people go to an expert just to get an opinion that supports their own; perhaps it makes them feel important if they're backed by someone with a title. You know, great minds think alike and all that. My tongue-in-cheek response is: “small minds rarely differ.”

I don't know about you, but I would only consult a so-called expert because I wanted to learn and for no other reason. I can humbly accept I don’t know everything and hence I look to be better informed wherever possible.

A different view of experts

A common perception of experts is that they know everything, but I just see them as people that know more about one particular topic than I do. An even better way of look at them is: “An expert is someone that has made all the mistakes in a very small field”. Either way, I would definitely exclude myself as an epoxy expert because I learn something new every day and continue to make mistakes regularly; and, I'm not ashamed to admit it!

I want to learn, seek information, question my beliefs and continue to look for better ways; I want to engage with people who have “made all the mistakes” in epoxy formulating, manufacturing, preparation, application, repair, maintenance and sales, so that I don’t have to.

Epoxy School isn’t about experts or egos

While I do not claim to be an epoxy expert and have no attachment to the term, I’ve come to know a lot about certain topics because of my desire to learn off these people and try things myself. Epoxy School is all about passing on this knowledge I have gathered as well as providing an environment where other epoxy users can ask questions and, more importantly, find answers. There are no “experts” here...or egos to stroke.

So, if you know more about a subject than I do then don't be shy, write a comment! I certainly won't take offence because I might just learn something. Better yet, why not put your hand up to contribute your expertise via written articles or videos?

Finally on the topic of experts, when someone wants to label my desire for learning and teaching as being some form of epoxy expert, I cheekily quote the following...it’s an oldie, but a goodie –

Expert (pronounced “X” - spurt): “X” being an unknown, “spurt” being a drip under pressure. Collectively, an unknown drip under pressure! Now, who would ever want to be an expert!? Haha.

Take care and talk to you later,


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Decorative epoxies - the polished concrete and warehouse looks

You’ve been asked to do a polished concrete or “warehouse” look for a client with your decorative epoxies – what do you need to know?

The traditional form of polished concrete involved 10-12 passes with a diamond grinder to hone the concrete into a smooth, glossy surface. While this type of flooring has been extremely popular in recent times, not every slab can be polished successfully and pricing is typically at the higher end. Because of this, a somewhat simpler and more cost-effective alternative can be done through the use of clear epoxies that rely on the resin to flatten the surface instead. This can be a very basic “grind and seal”, which results in the more rustic warehouse look, or, with the right product and thicker films, it can create a mirror-like, genuine polished concrete look.

Either way, if you think the idea of slapping a clear epoxy over concrete is a walk in the park, don’t be so sure! Believe it or not, there are few traps that regularly catch contractors out when taking on jobs like this.

Change your preparation goals

First and foremost, the polished concrete look and warehouse look will benefit from a slightly different approach to surface preparation. The natural inclination for many contractors is to whack a big, heavy grinder onto every slab and keep going until it’s completely flat. While there’s nothing wrong with that thinking as far as thorough preparation is concerned, ripping the tops of every high spot results in patchy, inconsistent aggregate exposure that rarely looks great in the final product. Instead, you want a grind that follows the contours of the slab and only removes the top layer across the entire area. An example of this type of thing is something called Diamabrush, which uses diamonds on flexible brushes to do just that.

Clear epoxies aren’t dead basic!

Ok, so you have a freshly prepared slab with a relatively even “salt and pepper” appearance. From here many contractors would simply mix up their clear epoxy, pour it onto the floor to roughly spread out, and then start back rolling. The problem with this practice is you can often see a dark patch form under the thicker sections of the poured clear epoxy – what I call the “pour line”. You can never fix such a blemish if it shows through the final coat, so you need to prevent it by changing your approach when working with clear epoxies, i.e. working from a roller tray is generally a safer option on the first coat.

This type of staining effect can also cause headaches in other situations, especially when applying in warmer weather. In these instances, the hotter conditions lead to large variations in the viscosity of the clear epoxy, i.e. freshly mixed product is thin and soaks into the slab easier (looks darker), whereas older product that has begun to gel is much thicker and doesn't penetrate as much (looks lighter). The result of this viscosity difference is the appearance of noticeable bands across the floor corresponding to the rolling pattern used, and is particularly visible where an old mix meets a new one. Once again, there’s no quick fix and prevention through measures such as smaller mix volumes is the only way around it.

Another potential trap when working with clear epoxies is the formation of “holidays” or, in simple terms, missed spots. Unlike the staining that happens on the first coat, holidays are more common in latter coats when the finish is darker and the clear epoxy isn’t as easy to see. Unfortunately these defects always have a habit of standing out much more the next day and can only be rectified with extra coats and extra cost. I’ve found the use of low-level lighting to be an effective way of reducing the number of misses, however there’s no substitute for working carefully and using a slow, methodical approach to application.

Your clear epoxy must be capable

The final point I want to make on the polished concrete look and warehouse look is an important one: you have to make sure your clear epoxy is actually capable of delivering the finish you’re after. The main focus in this sense is how well it flows/levels and the gloss it can achieve. The warehouse look is pretty forgiving and many clear epoxies will be suitable for that type of finish, however, I know from experience there are only a handful of clear epoxies that can make a good fist of a high-end polished concrete look. Regular readers of Epoxy School will know I always come back to doing homework on products before committing to any projects and it certainly isn’t any different here!

Take care and talk to you later,


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Surface preparation - does priming and sealing guarantee better results?

I know many contractors that prime or seal on every job, but does it always guarantee better results?

If you’ve read previous posts, you may recall I actually consider primers and sealers as different products based on the roles they perform (you can read the original priming and sealing post here). Regardless of what they’re called or how they’re used, a big question that comes into play on this topic is whether you always need to prime or seal. For me, the answer is no.

You can buy products that stick well directly to the substrate, eliminating the need for what I call a primer; you can also get well-laid slabs that aren’t porous or powdery and won’t need what I call a sealer to hold the surface together or prevent bubbles.

To take the argument against priming or sealing EVERY time a little further, I can even give you examples where it actually caused trouble rather than solved it. In one particular case I remember, the use of a sealer only managed to compromise the adhesion and cause some massive headaches for the contractor. There’s actually a lot to learn from this story and it’s worth covering in detail, so I’ll break it down for you here.

Flooring failure in garage caused by misuse of sealer.

Priming and sealing problem – beginning

The contractor at the heart of it all wanted to make sealing a standard step in all of his garage flake jobs so he could overcome the variation in concrete quality he was seeing and simplify the quoting process.

The solution he came up with was to apply a certain water-based epoxy (WBE) as a sealer on all the slabs. Being a very cheap product, the overall increase in material cost was minimal and far less than other sealing options – a big bonus in his view. The product manufacturer also recommended adding extra water to make it easier to apply and allow it to soak into the slab more. Fantastic! Even less cost.

Intercoat adhesion tests were conducted to prove the concept and the water-based epoxy failed concrete every time. It was fast enough and seemed to seal the surface well enough, so his plan all seemed to be falling in place.

Just when he thought he had it all worked out, a few problems began to appear. On one floor a small piece of coating let go directly beneath a rear wheel. Hot tyre pick-up, as it’s known (read more here), is a pretty common occurrence on garage floors covered with cheaper floor paint. The heat of the rubber softens these films, creating a temporary bond strong enough to prise small sections off the concrete. For two-pack epoxies, however, the heat isn’t an issue and this kind of failure can normally be traced back to surface preparation instead. When the underside of the failed coating was examined, there was a full layer of concrete visible suggesting that wasn’t the problem either. Something else was going on.

At the time it was determined to be particularly weak concrete at fault, probably due to it being rain affected or something like that. Anyway, the area was patched and life moved on.

More time passed and another failure popped up...same problem, different floor. Initially the same conclusion was reached, but maybe there was more to it? One failure wasn't enough to be concerned about and two in the space of a short time could’ve just been a coincidence, however some digging was done anyway to see if a pattern was emerging.

Priming and sealing problem - diagnosis

We understood the system worked fine on sound concrete via the adhesion tests, but when a weak slab was subject to stress (hot tyres in this case), the concrete would let go. We suspected the water-based epoxy was doing its job of sealing the slab to make it less porous, but was it somehow compromising the adhesion?

Further analysis revealed some very interesting facts. The WBE was a high solids product, but when diluted as per the instructions it would end up at 45%. Based on the coverage the contractor was getting – 1.35 litres/0.36 gallons of solids across 36m2/385ft2 floor – it meant a build of 37 microns/1.5 mils was being achieved at best, which isn’t much of a sealer at all!

In fact, very little resin was penetrating into the slab to provide the reinforcement these weak slabs needed. Because not enough was being used, it was simply sitting on the surface and forming a very flimsy basecoat of sorts that offered no extra cohesive strength to the concrete at all. Ok for good slabs, but disastrous for weak slabs.

The underside of the coating showing how the sealer didn't prevent the weak concrete from failing.

Priming and sealing problem - solution

The only solutions to this problem weren’t exactly what the contractor wanted to hear –

  • Apply the water-based epoxy thicker and boost the amount of resin per square metre to provide a proper seal for the weak slabs. The downside of this was the WBE became much less cost-effective and cured too slowly.
  • Use a solventless epoxy to seal the surface. Without adding any solvents, he could pull down the product to 150 microns/6 mils which would be sufficient to seal and prime the surface. The downside was this approach would add too much cost to each project and eat into the profit he was trying to make on each job.
  • Not apply a sealer and instead apply the basecoat at 30-35% thicker to allow for the absorption that would take place. Applying it thicker would leave enough product behind to flake into, but again it meant more product and more cost.

The moral of this story is you must ensure
primers or sealers are being used correctly and fulfilling their intended purpose or you could end up making the problem worse. Just putting a primer or sealer down in any old fashion definitely doesn’t guarantee better outcomes.

What is your experience with primers and sealers? Have you ever been in the situation where they were causing problems rather than solving them?

Take care and talk to you later,


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Epoxy troubleshooting - what is out-gassing?

Have you ever had bubbles that seem to appear out of nowhere in your epoxy floor? Well, that’s NOT out-gassing!

I often hear “out-gassing” being used to describe the cause of bubbles, i.e. bubbles somehow appeared after the product was mixed and applied due to gas formation. I don’t doubt that bubbles seemingly appeared out of nowhere, however the term out-gassing has nothing to do with film defects and bubbles have nothing to do with gas. In fact, the epoxy-amine reaction doesn’t produce any gas at all. The reaction is exothermic and the heat from large volumes can generate vapour, however this is only an issue when mixed in bulk rather than spread into a thin film.

It would appear there’s some confusion out there with regards to this topic, so let’s see if we can clear a few things up.

A bubble like this in an epoxy isn't caused by out-gassing.

The more common definition of out-gassing

In my experience, out-gassing is a term generally used to describe the process of volatile compounds (those that easily evaporate) migrating out of a floor over time and is therefore more of a health and safety issue than anything to do with defects. A common example of out-gassing in another context is the new car smell we all know and love. While this smell disappears over a few months, the materials in your car are still releasing these volatile compounds for a long time without you noticing it.

Thinking about an epoxy floor in the same way, there are volatile compounds that slowly move through the film and get released into atmosphere. Depending on the product they can be toxic or harmless; there can be a lot or just a little; they may all come out in the first 12 months or trickle out over a decade. There’s a great deal of variation in this sense, but the important thing to remember is it happens gradually and not within the space of 24 hours. If you can picture this then you can understand why I say out-gassing isn’t the cause of bubbles in your floor.

What causes the bubbles then?

Back to the original problem then: why do bubbles sometimes inexplicably appear in the floor after everything was otherwise looking fine?

One explanation is there may have been a heap of micro-bubbles you couldn’t see that joined up to form a large bubble. If that is the case, the obvious solution is to remove as many of these as possible before they get a chance to form something more visible. Unfortunately this isn’t always that easy.

Some will say that they can use spiked rollers. From my experience I’ve found spiked rollers to be effective with filled epoxy resins, e.g. a 2mm self-level floor, however not so effective with clear coats. Rather than pop the bubbles or bring them to the surface, the spikes tend to push them around instead or miss altogether. Others will tell you fine bubbles can be popped easily by putting a blow torch across the film. Not only is there doubts about the practicality of this method on large areas, it also carries safety risks and the flame can interfere with normal product behaviour.

In my opinion, a more frequent cause for the type of bubbles we’re talking about is the expansion of air in the slab. As the concrete heats up, air is forced through the pores and can be trapped in a freshly applied film. It’s the reason why I’m such a big fan of working in the afternoon when the slab is cooling rather than first thing in the morning.

How can we prevent bubbles?

As you can probably guess, prevention is always better than cure when it comes to bubbles on a floor. Here are a few handy tips for minimising their impact – 

  • The fewer bubbles created the better. Using a good mixer that doesn’t promote air entrapment is a good idea, as is staying away from the surface when mixing. Mix below at an efficient depth rather than beating the top.
  • The less you work the product, the less air entrapment. Also, the quicker you get off the floor, the more time for the resin to flow and bubbles to pop.
  • Product choice can have a massive impact on the amount of bubbles and defects you get. Do your homework and you’ll save yourself lots of headaches.
  • Finally, if the substrate itself is expelling air the chances are these tips alone won’t be enough and I went into greater depth about how to handle that in a previous post (Epoxy troubleshooting – bubbles, pinholes and craters).

Just for a quick review, out-gassing is the term used to describe the stuff that’s slowly given off by a floor or coating film. Bubbles aren’t caused by gas, but by air caught in the product through mixing and application or from the passing of air through the slab underneath.

Take care and talk to you later,


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Decorative epoxy flooring - high-gloss flooring maintenance

Congratulations! You've put down a stunning decorative epoxy floor. So, how do you keep it looking like new?

First of all, I should clarify this post is all about high-gloss flooring maintenance. If your floors have a semi-gloss or matte finish then you’re fortunate because that can often simplify floor maintenance greatly. High-gloss floors, however, can be really tricky for a number of reasons and require a bit of work to get on top of.

Example of high-gloss floor needing a sacrificial polish or other floor maintenance options.

High-gloss flooring maintenance options

When I first started looking at maintenance for my high-gloss floors many years ago, I began with side-by-side tests of three common options: epoxies, polyurethanes (PU) and sacrificial polishes. I’ll define a sacrificial polish as an acrylic or wax emulsion that’s typically applied with a mop and buffed to increase its durability and shine. In my very simple way of looking at it, which one to use would more or less boil down to how well they resisted day-to-day scuffing, scratching, spills and the like – you know, the usual wear and tear that gradually dulls a beautiful high-gloss floor.

From what I saw in those tests and have experienced since, the best of these finishes when it came to maintaining the original finish was a PU. From that, it might seem logical to conclude that a PU should be applied wherever possible and rest can be forgotten. Well, in my opinion, this isn’t quite the case and PUs aren’t always the solution to high-gloss flooring maintenance. In fact, I prefer to use a floor polish more times than not.

A PU isn't always the best option

So why aren’t PUs always the answer? Well, the number one concern I have with PUs on high-gloss floors is the gloss levels they are capable of themselves. Whether it’s a single-pack, moisture-cured product or two-pack, solvent-borne, I am yet to come across a PU that can consistently get near the same finish as a decorative epoxy. They are acceptable in some projects, but in my experience most clients are disappointed with the final result once a PU is applied (especially if they’ve seen the epoxy finish beforehand). PUs can also be difficult to sand, which makes over-coating troublesome, and compatibility issues can arise between epoxies and PU from time to time.

In that case, you might be wondering why putting another epoxy over my decorative epoxy floors isn’t the preferred option either. An epoxy will certainly hang around a lot longer than a polish and be easier to work with than PUs, however they tend to mark more easily and that’s obviously one of the things we’re trying to avoid in the first place.

That leaves floor polishes and, like I said, I often find they’re the best option for maintaining a high-gloss floor. Yes, they don’t last as long overall, but they generally offer good resistance to scratching and scuffing and are very easy to re-apply whenever it’s time to restore full shine.

What makes a good floor polish

Obviously not all floor polishes are the same and effective floor maintenance hinges on finding a good one. When sourcing a suitable polish, I want to find one that –

  • Can be applied by the client.
  • Can get a high level of gloss, preferably without buffing as most clients don't have buffing machines and don’t want to pay for it to be done.
  • Can be stripped back with a basic stripper if I need to repair or extend the floor.
  • Is cost effective.

There are tons of sacrificial polishes out there, and like every other type of product, they all sound the same when you read a data sheet. As always, you need to invest time in testing it out for yourself to make sure it can do the job. While you’re at it, find a good cleaner to complement the floor polish – something with a strong cleaning action that also delivers a streak-free finish.

Just in closing, one of the somewhat hidden benefits of using sacrificial polishes for high-gloss flooring maintenance is the fact they encourage the customer to look after their own floor rather than rely on a permanent topcoat to magically last forever. All floors need regular maintenance and if you can put together a good floor maintenance program for your clients it will not only ensure they take responsibility for the care of their floor, it will give you a great “value-add” product to offer as well.

Take care and talk to you later,


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Decorative epoxy flooring - colours, techniques and practicalities

So you've worked with epoxies for a long time and done some decorative work along the way, but do you really understand colours? Do you feel confident creating designs and putting them on a floor?

Let me start by saying I was educated as an engineer, so I have no right to understand colours. Even worse, I started out in the epoxy field working almost exclusively with dull, industrial grey coats. You might remember a recent post (Metallic epoxies – the smiling contractors!) where I said it was only after starting my journey into decorative epoxies years ago that I began to realise resin flooring could be fun, exciting, and of course, colourful!

It goes without saying that understanding colours and how to make them work in a practical sense didn’t come easy; however, I’ve spent a lot of time chipping away at this topic and gradually built up a valuable knowledge base. If you have loads of time, patience, and maybe even money, then you too can learn the hard way. Alternatively, you can just learn from me!

So, what are some of the key points I’ve learnt about colours, techniques and how to get the most out of decorative epoxy flooring?

Turning descriptions into floor ideas

First of all, you need to be able to understand the language of colours before you can dream up flooring designs. If you’re like me and lived in a plain colour world – and yes, I consider flake or coloured quartz as plain colour flooring – then you either need to have an untapped natural flair for this or you need to train your brain on how to interpret colours. “Hold on a second here, I’m not colour blind”, I hear you protesting. Good! That will help, but it’s not really what I’m talking about. Interpreting colours goes deeper than knowing the difference between red and blue. I’m talking about the ability to give a client what they want based on common descriptions they use, like wanting a floor that’s “warmer”, “cleaner”, “brighter” etc.

Turning flooring ideas into flooring designs

With resin flooring, you typically have no more than one millimetre (40 mils) of floor coating to produce depth, intensity, variations and highlights. To be able to do that effectively you have to be clever with the way you combine resins, pigments and application techniques. Only by understanding finer points like how the texture of a basecoat affects the appearance of the topcoat, or how pigments flow and settle in different resins, will you ever be able to consistently deliver suitable flooring designs for your clients.

A decorative epoxy design showcasing the striking effects possible.

Turning flooring designs into actual floors

Interpreting the colour language used by clients and skilfully whipping up their dream floor on a sampleboard is an achievement in itself, however it all stops there if some important practicalities are ignored. To put it simply, you must only do on a sampleboard what you can reproduce on a floor.

There are a few things that will dictate whether or not a flooring design can be scaled up from a board to a floor. Ask yourself: are the application techniques I used possible on a large floor? Will they deliver a consistent and reproducible effect? Will it take too much time or perhaps even drive you crazy with “fiddly bits”? How thick is the total film build and what does that mean for material costs? Can you compete price-wise with established flooring alternatives like tiles, carpet, timber and vinyl?

Again, all these aspects of decorative epoxy flooring didn’t come naturally to me. I spent many late nights experimenting with colours, application techniques, designs and have only learnt the practical side by costly trial and error. If you’d like a quick and easy shortcut through all that pain, please have a look at the Decorative Epoxy Flooring Master Class in the Epoxy School shop. It passes on all of my knowledge and understanding of decorative epoxies, as well as the designs themselves, so that you don’t have to learn the hard way like I did.

Take care and talk to you later,


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Health and safety - epoxy sensitisation

Have you ever had, or heard of someone, get a skin rash when working with epoxies?

Well, that skin rash could well have been a form of epoxy sensitisation. In simple terms, epoxy sensitisation describes the process in which your body becomes more and more sensitive to epoxy products and/or the chemicals used in them. Perhaps the most common sign of epoxy sensitisation occurs on the skin via rashes, however irritation to the eyes, nose, throat and lungs can also occur.

The funny thing about sensitisation in general is that everyone reacts differently. Some become sensitised to certain chemicals very quickly, while others can experience high-level exposure their entire life and never feel a thing! Another quirky fact is sensitisation typically isn’t localised, i.e. the symptoms don’t always line up with the cause. I’ve heard of contractors being hospitalised, unable to see out of either eye, yet they didn’t get product anywhere near their face.

A skin rash typical of epoxy sensitisation.

Epoxy sensitisation – what I’ve learnt

Obviously the thought of an itchy skin rash or swollen eyes isn’t very pleasant at all and if you want a long, successful career in epoxy application, you must protect yourself. Here are a few key tips I’ve learnt about avoiding epoxy sensitisation

  1. Treat every chemical as though it will cause sensitisation and avoid skin contact. Wear long sleeve shirts and pants. If you get product on you then remove the item of clothing and wash the affected area with soap and water. If you wear short sleeve shirts then use barrier cream on your arms and hands.
  2. Start wearing gloves. Many contractors shy away from using disposable latex gloves because they can be hard to change when hands become sweaty. An effective way around this is to put on a thin pair of cotton gloves underneath the latex gloves as the cotton absorbs the sweat and makes it easy to change. Double gloving is also an easy way to keep clean – if the top gloves get dirty, just rip them off and keep going. While on the topic of latex gloves, buy powder-free gloves as users can actually develop sensitisation to the powder/sweat combination produced while they work.
  3. Work as cleanly as possible and wipe dirty items on rags, not shirts or pants.
  4. Some chemicals will cause sensitisation much quicker than others. Generally it’s not the epoxy resin (Part A) that causes the problem but the curing agent (Part B). Some curing agents are more reactive than others and can cause sensitisation quickly if not handled carefully.
  5. There are certain parts of your body that are more sensitive than others when it comes to skin contact. The underside of your forearms is a common point of exposure and often the first area to show up in a rash. It goes without saying that you must wash your hands before eating or going to the toilet as these regions are also very sensitive.
  6. Wear a mask. This should be a given for solvent-borne users to avoid breathing in harmful solvents, however even solventless epoxies give off a small amount of vapour that can build up in confined spaces and cause problems.

The final tip I want to give is the one that you must take away from this post if nothing else: whatever you do, do not use a solvent to remove epoxy from your skin! The solvent breaks down the epoxy and makes it much easier to remove, but it also makes it much easier to penetrate through the skin and enter the body. This fact should be kept in mind for solvent-borne epoxies – these products already have solvents in them, which makes skin contact even more dangerous in this context.

Once sensitised to epoxies...

Ok, so you get that epoxy sensitisation isn’t a good thing and you know how it can be avoided. What happens if all that fails and you become sensitised; or you’re reading this and are already sensitised? If you are sensitised to epoxies then there it generally goes one of two ways –

  • You might be lucky and only develop sensitivity to a particular raw material within the epoxy – something that isn’t found in every product. In this case you can find a suitable alternative that did the same job and continue working (as long as you worked clean).
  • You might be unlucky and become sensitised to the epoxy resin, which is a much bigger problem because it could mean every product is off limits. This situation is the real tragedy of epoxy sensitisation because it can ultimately strip a contractor of their livelihood. Their body is telling them it can’t cope with the chemical exposure and unfortunately the only option at this point is to seek another profession.

Avoid epoxy sensitisation from the start!

As I said before, if you want to work in the epoxy industry over a long period then you need to develop the right habits from day one: work clean, protect your body, clean up without solvents and read material safety data sheets to understand what the potential dangers are. If you ignore any or all of these things, epoxy sensitisation could make your life misery and even spell the end of your career.

Take care and talk to you later,


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Epoxy troubleshooting - solvent entrapment

What is solvent entrapment and why is it bad news for two-pack epoxy coatings?

If you thought solvent entrapment had something to do with solvent becoming trapped in a film then you’d be 100% correct. There’s nothing tricky about the name, that’s for sure! Just like anything though, knowing what it is and what it looks like is the easy part; knowing why it happens and how to avoid is where the gold really lies.

Basically, solvent entrapment can be boiled down to one thing: the solvent not having enough time to evaporate from the film before the hardening process goes too far. When applied correctly, two-pack epoxies containing solvent normally have enough time before this happens, however if they’re applied too thick or in cooler, damper conditions, the components can crosslink before the solvent escapes and this can lead to a variety of problems.

Although solvent entrapment can happen in solvent-based or water-based products, the way it affects the film is more a factor of how much solvent is used rather than the type of epoxy.

Solventless epoxies and solvent entrapment

As I’ve already written in a previous post (Solvents – their purpose in solventless epoxies), some solventless epoxies can have a small volume of solvent added to extend pot life or drop viscosity. Despite the very low solvent content (typically 5% or less), solvent entrapment can still be an issue and tends to compromise a film in two ways -

  1. Soft spots – solvent trapped in the film can create a physical barrier to crosslinking in isolated sections and stop these spots from fully hardening (hence the term “soft spots”). This phenomenon is even more likely if acetone or MEK is used because they belong to a group of solvents called ketones that block the chemical reaction with the amine.
  2. Blistering – if the solvent has a relatively high boiling point and won’t evaporate quickly then you not only raise the risk of trapping it in the first place, but you’re also more likely to see blisters develop. This happens because solvents with higher boiling points are often hydrophilic, which means they attract water and could draw enough to form visible blisters.

Solvent-borne, water-borne epoxies and solvent entrapment

If those are the main dangers of low-level solvent entrapment in two-pack epoxies, what happens when the solvent content is much higher, for example 70% in a solvent-borne or water-borne epoxy? In this situation, you typically see a different outcome. Rather than a small pocket of solvent permanently held captive in the film, the majority manages to gradually work its way out as the film tries to crosslink and what you end up with is a porous, sponge-like structure across widespread areas. Instead of a strong, hard film, you’re left with a much softer, weaker version that is also commonly affected by a large number of shrinkage cracks (called “mudcracking”).

It’s important to mention at this point that extra care must be taken with water-borne products and entrapment problems because of the lower volatility risk I touched on in my comments on blistering. Water will not evaporate as quickly as organic solvents and therefore these kinds of products are more prone than others.

Mudcracking in a water-borne epoxy.

Solvent entrapment traps

OK, so you’re probably thinking, “If I stick to applying as per the manufacturer's specification, I should not run into trouble, right?” In theory that’s correct, but sometimes it isn’t always that straightforward. For instance, what happens on a slab with “minor” depressions that exceed the allowed thickness? That’s just one scenario where you could unwittingly be heading for a problem and the only way you could avoid costly defects there is to have a good understanding of why solvent entrapment occurs in the first place.

Take care and talk to you later,


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Selling epoxies - how time off will boost your epoxy business!

I recently took my first break since launching Epoxy School and I must say it put a few things into perspective.

We work in an industry where it’s customary to take the work whenever and however it comes, putting in long, strange hours and even giving up our weekends to get it done. As business owners, it’s fair to say we bury ourselves in our job – to the point where we feel guilty if we’re NOT working!

A key to boosting your epoxy business

I decided to write this article as I relaxed on the couch during my break and thought about all the business owners I’ve met over the years that didn’t take any time off at all. What impact would it have on them in the long run? Was that level of output sustainable? Did it actually help them “get ahead” or did it hold them back in some way? It may sound ridiculous to some, but once again I came to the conclusion that taking time off really is a key to making more money in your epoxy business.

A hypothetical epoxy business owner on holiday, relaxing on the beach.

How time off makes money

The way I see it, taking time off can you boost your epoxy business by allowing you to –

  • Relax the mind. A relaxed mind makes fewer mistakes and that alone will save money! A relaxed mind has better planning ability and far more creativity, which is a big part of how you make money. A relaxed mind also stresses less, which allows you to think about the “right” things and not get bogged down with the small stuff that doesn’t matter.
  • Let the body recover. The human body is a phenomenal bit of gear. You can punish it in all sorts of ways, yet it still bounces back if you give it enough time. Unfortunately most of us don’t and that’s when we strike trouble. Not only does a worn-out business owner work less efficiently day to day, they also run the risk of a catastrophic breakdown sooner or later. As a business owner, you’ve got to acknowledge your health is your number one asset – if you can’t keep working the whole show stops!
  • Get your equipment serviced. When you’re busy you can easily forget about the maintenance that stops your equipment from packing it in when you least want it to. Surface preparation gear is probably the main concern here because it’s a mind-numbing task and you tend to focus on chopping down the trees rather than sharpening the axe, so to speak. Your vehicle also sits in this category. It not only gets you from A to B, it’s often your travelling showroom as well and what people judge you on first. Make sure it’s running well and representing your business in the right way!
  • Think about your future. Go see a financial planner or your bank manager and see if you can sharpen things up there. Also, look ahead and think about what your epoxy business might look like in the future. Where do you want to take it and how can you start moving in that direction? When would you like to get off the tools? Can you continue to make money if you’re no longer working?
  • Think about other elements of your epoxy business. Obviously your employees are a key part of this process. How can you give your employees time off as well so that they can recover and be at their best for your business?
  • Spend time with the people that matter most to you. It is why we work, after all! Let them motivate and re-energise you and clarify exactly why you’re out there working your butt off.

If you look at the list above, I’m sure even the biggest workaholics among us could appreciate the benefits of taking time off and how it can help you make money. The hard part is, I believe, having the courage to take your nose away from the grindstone and give it a try. As a wise man once said to me, “there’s a time to work and a time to play. Don't mix them up!”

Take care and talk to you later,


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Epoxy troubleshooting - UV exposure and indoor epoxies

We all know epoxies will yellow outside, but it may come as a big surprise to hear indoor epoxies aren’t entirely safe either!

As already discussed in a previous post (Epoxy secrets revealed – do UV-stable and low-yellowing epoxies exist?) , all epoxies will break down in direct sunlight and much of this has to do with a chemical structure that isn’t very stable when it comes to UV light. Because of this, and their excellent all-round performance in other areas, epoxies are naturally better suited as indoor coatings and are widely used in factories, warehouses, commercial kitchens, offices and homes. But, don’t be fooled! Just because these films are applied indoors, doesn’t mean you can’t be burned by UV exposure (pardon the pun).

Roller door line showing indoor epoxies can yellow.

UV exposure can still happen with indoor epoxies!

Here are a few points on what I’ve learnt about indoor epoxies and UV exposure – 

  • Although UV exposure can lead to other film issues, the main danger indoors is yellowing. You’re not likely to see obvious signs of chalking or cracking because indoor coatings generally don’t have to contend with rain or extreme temperature fluctuations. 
  • The way UV exposure occurs indoors is through windows (and large entrances such as roller doors, although that’s a more obvious danger). Luckily, there are countless combinations of glass and nowadays it’s not uncommon for it to be laminated and contain some form of UV blockers, which significantly reduce transmission levels. Double-glazed and tinted windows do the same thing. The last point to consider with UV exposure through glass is the aspect. In the southern hemisphere, northerly facing windows allow maximum UV light exposure. 
  • A forgotten source of UV light indoors can be fluorescent tubes. I’m no lighting expert, but as I understand it a new fluorescent tube has a lining on the inside that gets “excited” by UV radiation, converting it into the white light we see. Over time this lining degrades, which allows the UV light to escape from the tube and come into contact with indoor coatings. Likewise, IR heat lamps in bathrooms can also cause problems. IR is a bandwidth that gives off heat, not just visible light, however it’s possible enough UV is given off to discolour vulnerable surfaces.

Final thoughts on UV exposure

With this post and the previous one, we’ve covered a fair bit on UV exposure and yellowing. While there’s much more to say on this important topic, for now I’ll close with a few scattered notes to also think about – 

  • To repeat a well-worn line, it’s important to understand and accept all coatings will yellow to a degree. Some will more than others and you must do your homework when it comes to product selection. 
  • Any colour with yellow in it will tend to show less yellowing. In other words, yellowing in beige, green and even some greys won’t be anywhere near as noticeable as other colours and this can be used to your advantage where UV exposure is a concern. White is clearly the worst as a telltale, although that doesn’t stop it from being a very popular choice! 
  • Yellowing tends to stand out more when side-by-side with a clean section. For example, an old mat or pot plant at the entrance of a plain glass door will reveal a very neat yellow border when removed. 
  • Zinc oxide, a widely used filler to help reduce the effects of UV light, has a high natural affinity for lead. While there are grades available with low lead content, they’re not always the first choice for manufacturers trying to keep costs low and that’s something to keep in mind if you’re trying to avoid hazardous materials.

Take care and talk to you later,


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