JEM Watercraft

I am getting ready to build a wf27 this winter ( in St. Louis, can get cold ) what kind of temperature range can epoxy tolerate and can I safely use a propane heater in the enclosed space as a heat source.
Please excuse my ignorance.

Thanks For your help

Jim G

Hot weather it sets up quicker and in cold weather slower. It depends on the temperature in your work area and the speed that your epoxy sets up at. Slow , med or fast. Epoxy sets up with a heat reaction caused by the chemicals in it. Mix it wrong ( to much hardener ) and it will smoke and burn your hands so be careful when mixing it.

Acetone is normally used to remove epoxy and clean up the items you used . That in a enclosed room with a spark or flame is a recipe for disaster. Acetone is very volatile.
Have some dam good fire insurance because there is a 99% chance you will be using it if you use acetone in a enclosed area with any type of flame or spark around it. .

Personally I would not work with epoxy in any enclosed area , only in a well ventilated open area. Some folks are allergic to just the fumes from the epoxy.

That's just me , as far as the rest of the folks I hope they share their information with you.

If I want to reuse brushes etc I wash them in vinegar. Squeeze out as much resin as possible with paper towel, then wash 2 or 3 times in a small quantity of vinegar, discarding it each time then wash in water 2 or 3 times and allow to dry thoroughly before reuse. The vinegar is acidic and the epoxy reaction relies on being in an alkaline state so the vinegar neutralises the reaction. This is why it is important to rinse the vinegar out of the brushes thoroughly.

You should wear gloves but of course sometimes resin gets on you anyway and in this case vinegar is better for cleaning your skin too.

As for the fumes , yes some people can react but personally I find it OK especially compared to the massive hit from the solvents in polyester resins. Some ventilation would be advisable.

In cold weather the epoxy will still go off but it may take a very long time ie days or even weeks. If you glue up some scrap pieces at the same time as the real bits you can unclamp the scraps first and make sure they are set. If they fall apart then you know it is too soon to unclamp the workpieces.

At the other end of the scale if you go into summer and are working on very hot days make sure you only do small batches as large ones generate a lot of heat. I've had one smoking and that was after I divided it in 2 to keep the heat down.

Not intending to hijack this topic, just seemd like an appropriate place for my question instead of opening a new topic...

My question is .. Has anyone here tried RAKA's # 425 Hardener(Cold Weather Hardener)?

It's looking like my JEM Trapper build in my basement will be done at temperatures ranging mostly in the 50s and 60s Farenheit,
maybe getting into the 70s occasionally. I am a novice epoxy resin user so I am leary of getting all fast hardener.
Maybe I should order equal amounts of RAKA's fast 610 and slow 606, and mix them in ratios per the temperature at the time,
but now I see where RAKA offers a medium hardener, #608, and now I see where he offers this "cold weather" #425 hardener.

I'm reluctant to get this cold weather 425 one because it mixes 4 pts resin to 1 pt hardener, instaed of 2:1 for all the others, ans I think that 4:1 is more subject to error.

Any opinions from you all that might help me decide will be much appreciated.

Haven't used Raka so just some general comment.

I bought some fast "hardener" for my system once and found it blushed. I believe that with all brands the faster resins will have more free amine than the slower ones and so will be more likely to cause blush. I only ever use the slow versions now.

I would not go mixing fast and slow components unless specifically advised to by the supplier. In some cases it will be OK but not in others.

My brand is a 5:1 ratio and I have only ever had one bad batch - due to being interrupted and forgetting to mix it . If you work out a reliable measuring system and stick to it you will be fine.

One thing I do that helps is measure the part B first. If I go a little over then I can add a bit extra of the Part A.
Because of the 5:1 ratio a small overrun in the part A (the "5") is only worth 1/5 of that same error in the part B.