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Solventless Epoxies and Cold Temperatures

By Jack Josephsen

When the cooler months roll around and temperatures drop, application can start to become a bit of a headache for contractors.

As a manufacturer of solventless epoxies, I can always bank on being asked two questions during these periods:

  1. How can I make solventless epoxies easier to apply?
  2. How can I speed up the cure?

Obviously the answers can depend on the products being used, but there are a couple of things that help regardless.

Cold temperatures and solventless epoxy preparation

Firstly, let's take a look at making solventless epoxies easier to handle.

Step one involves getting the product out of the bucket and in single digit temperatures (1-10oC/34-50oF) the thick viscosity can make that a task in itself. With this in mind, storing the product on the floor in a cold shed is not going to help your cause. Instead, look to store the product in a warmer space, somewhere indoors away from the extremes and closer to 25oC/77oF. It doesn't have to be in your bed, although that would be perfect!

Keeping the product at moderate temperatures this way will also stop the products from turning into a gluggy semi-solid, which can happen with some solventless epoxies in cold temperatures. Crystallisation, as it’s known, can be reversed by slowly heating and stirring the product, however you certainly don’t want to be doing that every time!

If storage at a reasonable temperature isn’t possible, some contractors make special “hot boxes” to warm the epoxy directly before use. These devices are essentially timber boxes that house a few kits of product and are heated via an electric fan-forced heater. There are also submersible heaters available that can keep certain volumes at a constant temperature, however I’m not too sure how practical they are in the field.

An example of a hot box used to warm epoxies before application in cold temperatures.

Cold temperatures and solventless epoxy application

These little tricks might work well for getting the product up to a nice mixing temperature before use, but even that may not help you if the slab itself is extremely cold. A cold slab will tend to act like a big heat sink and this means even if your pre-heated product is 30oC/86oF when it hits the floor, it’ll quickly drop to the temperature of the slab once applied and drag you back to square one.

This cold substrate issue can be eased by heating the room, however if you're using a gas heater and your epoxy has a problem with amine blushing you’ll need to be extra careful. These heaters increase the levels of carbon dioxide when operating, which is one of the key ingredients needed for blushing to occur. This warning can actually be extended to any heater that doesn’t burn clean and therefore could potentially interfere with the flooring, e.g. kerosene heaters have been linked to adhesion problems.

Apart from heating, there’s also a school of thought out there that suggests using a thin epoxy to seal the surface first can make epoxy application easier because it protects the thicker basecoat from the icy slab. Such an approach may be worth trying if you can work in the additional cost and time of an extra coat.

Cold temperatures and accelerating cure

Finally, cold temperatures also mean slower reaction times. If your solventless epoxy isn’t adversely affected by heating as already discussed then continuing to heat the room after application can be a good way to achieve a shorter turnaround. Besides that, the answer to speeding things up is the use of a stir-in epoxy accelerator. Be aware these additives can affect the UV and chemical resistance of the product, so never use them in quantities greater than recommended and never in the final coat if possible.

I’ll finish off by adding that introducing a small amount of solvent to a solventless epoxy is also a popular way of reducing viscosity and making epoxy application easier. Unlike the other options given here, however, adding solvents won’t cut cure times in cool conditions and some solvents like acetone will delay it even further!

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