Temperature and epoxy question

[Matthew Curtis]

It is not uncommon for my shop to be 50 degrees when working, or even colder in the winter before I crank up the heat.

I have been looking into getting some epoxy to fill voids and the occasional adhesion of joints.

What do I need to consider when using epoxy in these temperatures?

What things can I do to improve my results?

What epoxies would be good choices?

I see that west systems fast cure epoxy is good for cold weather (down to 40) but also has a pretty fast working time (9-12 min). I would like a longer working time than this.

Thanks for the help.

[Bryan Lisowski]

You really need to read the directions on the epoxy you end up choosing. I would get the shop up to temperature and try to maintain for 12-24 hours.

[Mike Henderson]

Epoxy cures by chemical reaction and the reaction goes quicker in warmer temperatures. When I use epoxy to fill voids, I let the epoxy cure until it's firm to the touch and then I put it outside in the sun to get it to cure hard. It needs to be hard before you try to sand it or it will be like gum. It will clog your sandpaper and not sand smooth.

Try to let the epoxy sit for 24 hours before sanding and you'll have better results.

For gluing up work, if you're using a fairly slow epoxy I'd leave it in clamps for at least 12 hours. Better to be safe than have a joint come open on you.

Mike

[Kevin Jenness]

If you pour it into a flat pan to avoid heat buildup West System 105/205 (fast hardener) will give you up to an hour working time at 65 F before it will gum up to the point that you can't pull joints together with clamps . It gradually thickens from honey consistency through peanut butter to soft wax. For more working time use 206 (slow) hardener, put your pan in an ice bath or work at a lower ambient temp. At 65 a thin layer of the fast mix should set up in about 4-6 hours to where you can't dent it with your thumbnail, at which point a non-stressed joint can be unclamped but full cure won't take place for at least 24 hours. If you are trying to lay up fiberglass the working window is much less as you need the fluidity of the initial mix. In any case just mix up what you can use within the working time- let experience guide you.

Low temperatures slow the cure considerably. If you can't heat your shop overnight you might consider tenting off an area and using a space heater or keeping your assembly warm with an electric blanket.

[Matthew Curtis]

If you pour it into a flat pan to avoid heat buildup West System 105/205 (fast hardener) will give you up to an hour working time at 65 F before it will gum up to the point that you can't pull joints together with clamps .

It really is that long at 65 F? The pot life is 9-12 minutes at 70F.

Has anyone used the special clear Gardner from West systems?

[Jamie Buxton]

Epoxy in a mixing cup self-heats as it cures, and because of that heat, it cures faster. The same epoxy spread out in a thin film does not self-heat. So pot life is shorter than working time.

[Matthew Curtis]

I guess I don't want understand what pot life is?

[Jim Becker]

I guess I don't want understand what pot life is?

Pot life is essentially the amount of time you have after mixing the product before it starts to cure enough in the mixing container so that it doesn't apply to the workpiece smoothly and correctly. It's still "wet" but the exothermic/chemical curing process has moved along to that uncomfortable point where applying it isn't a good idea...

[Wes Grass]

We had some that was intended for injecting into molds, for rapid cycle composites. Guy mixed a small cup, couple ounces, and within 2 minutes it started smoking. He carried it outside, where it melted the plastic cup into the asphalt.

[Kevin Jenness]

Working time really depends on what the task is. If you need to roll out the mix you have less leeway than clamping up a door.

207 is best reserved for coating applications due to its expense. It does need to be topcoated if exposed to sunlight.

I have had a batch in a tray kick off in hot weather- a smoking hot toxic mess- had to throw it out the 2nd floor window. Don't let it happen to you!

[Jamie Buxton]

I guess I don't want understand what pot life is?

Go to the West System web site. www.westsystem.com At the top of the home page, pull down from a heading "instruction". You will find loads of information about epoxy, catalysts, and temperature.

[Larry Frank]

Every epoxy is different. You should read the directions on mixing and curing for each.