You have air conditioning?

MAS LV products have much less tendency to "blush" (an amine substance that will float to the surface of uncured epoxy when the ambient humidity is really high during a prolongued cure) than some other brands so best if you can time your epoxy work for when humidity's going down while the temp's fairly consistent or going up.

Humidity goes down as the temp goes up 'cause warm air holds more moisture than cool. When temps drop the humidity goes up, why cool objects get condensation forming on them when exposed to warm, humid air. 

Risk of crystallization with epoxy resin is greater when it's stored in cool conditions. I wouldn't refrigerate it if I were you. Hardeners aren't affected as much.

It's tough to tell if resin's crystallized when the container's opaque. You don't want to use crystallized resin, and it goes back to liquid once brought back to typical room temps of 65° - 75°F.

Give us an idea of the temps you store your components at and those of your workspace when you're mixing and applying it please. 60 - 75° is optimum for both; above that you want to work with small quanties that are mixed and applied within as short a time frame as you can manage.

Also helps to put mixed epoxy into a container where its surface area's fairly large; think cookie sheet or cake pan not mixing cup. When the stuff's mixed and the volume's concentrated in a relatively deep layer it heats quickly. If you can mix it then get it onto your work, or transfer it to a flat container so it's not too deep it'll stay cooler and won't 'kick off' quite as fast.

I know builders who place their mixed batches in icewater baths to keep it cool before application. If your project's warm the mixed epoxy will quickly warm once it's placed.

Crystalization only happens if the resin is frozen, so refrigerator temps should be safe. Just don't contaminate food surfaces with the toxic gunk on the outside of the bottle. A dedicated cheap ice chest would be much safer.

To get rid of crystals quickly and reliably you need to put the resin into a 140 °F (60 °C) water bath.

Laszlo

   Thanks for the quick responses! I was hoping to put some fillets down today. I'm using pastry bags so keeping the mix spread out isn't an option. I've got a little mini fridge that I use for drinks in my shop that I will dedicate for Epoxy only.

SB

Laszlo & I usually can agree (his experience is greater than what I lay claim to) but in this instance I have to counter what he'd posted based on what I've seen since I began using MAS LV product.

Kept in my basement, never lower than maybe 55F in the dead of winter, with a gallon of resin stored on a shelf up off the floor I've seen white precipitate / crystals settled out in the bottom half of the jug. These quickly disappear after a hot water bath and a little agitation. Once properly mixed with hardener it cures as expected.

Now when I'm planning for an epoxy session I bring resin & hardeners up to 75-80F before mixing. This makes for more complete mix and the stuff seems to wet out glass cloth a little more evenly besides being more readily spread out onto surfaces.

I'd go for cooler temps if planning for non-horizontal application however, it will run when too liquid.

   I've built three boats and repaired others in the hot humid Florida outdoors and the epoxy held up better than I did.  I used MAS Slow Hardner measured by the pumps.  Measuring  by volumn with a measuring cup has been a problem for me in sweaty conditions. Perhaps mixing smaller batches that can be spread before pot time expired is the key. 

   I thought I'd get back with everyone about my experience, I did use the cooled epoxy and it was harder to pump and mix. Used pastry bags which worked well and curing is going as expected, even being chilled the bags did start to warm up. I would do it again for small batches for fillets but when I glass the exterior of the hull I think room temp would be better. Easier and faster to mix and spread for larger batches. Thanks again for everyone's input it really helps for this first timer.
SB

So spclark's post about crystalization without freezing got me curious. Taking the position of "Never argue with observed facts" I went digging for an explanation and it seems that room temperature epoxy resin is a supercooled liquid just waiting for a trigger to make it crystalize. In that way it's like the supercooled water that makes ice storms and snow.

In addition to the already-mentioned freezing, triggers also include anything that provides nucleation sites. This would include contaminants like dust, water and dried-out resin. A tiny crystal forms at the nucleation site which then acts as a larger nucleation site for more crystals, sometimes resulting in a chain reaction. In the early stages the resin will look foggy from the suspended crystals. As they get larger they will precipitate out and form the familiar white crust on the inside of the container.

So to avoid epoxy resin crystals, besides avoiding freezing, one should also keep the containers tightly sealed in humid weather, never pour unused resin back into the bottle and keep the lids and container edges scrupulously clean.

Or just be on the lookout for the crystals and be ready to dissolve them back into the resin with a hot water bath.

Laszlo

San Bernard,

Thanks for getting back to us. It's always good to have the reality check.

You are quite right about chilled epoxy being much more viscous, which makes the work of laminating glass harder.

The days and nights here in Maryland aren't usually Gulf Coast hot, but they can approach it. In the past when I was still a wage slave, the summer after-work temps could approach 100 °F, killing any possibility of after-work glassing. So what I did was prepare everything the night before, keep the jugs in the basement and get up before sunrise to get the epoxy work done before the temps hit 80.

I don't know how cool it gets at night for you, but that might be an option.

Laszlo