Epoxy takes days to cure when very cold

[Spot]

Originally Posted by Boatyarddog

Should ask the question WHY chemically resistant gloves are not being used working with Acetone Or Epoxy.
Just looking for trouble and reactions to the stuff.
West systems has some different hardeners as well.
Don't touch the stuff much, and remove it from skin.
Another trick is Vaseline rubbed on hands if not using gloves.
It creates a barrier that keeps the epoxy away from skin, and comes off easier.
Boatyarddog

True, true. It took me a couple years and hearing about someone I admire becoming allergic to epoxy to finally cure myself of not wearing gloves before opening the bottles. I need to better extend this practice to solvents in general and not rationalize it away for 'just a quick wipe'...

[Chotu]

And then it’s possible to use all the tricks and still become just like me. I cleaned up with vinegar. I religiously used gloves. But I built a whole 50’ x 25’ boat out of epoxy. So that will do it. Lol

[tronic72]

Originally Posted by capt jgw

Epoxy sets by a thermal reaction. The cooler the ambient temperature the slower the reaction. Also the thinner it's spread out the more the heat will dissipate and the slower the set. We can use this to advantage like mixing a large batch and putting it into a roller tray instead of leaving it in the pot. In temps maybe down to freezing, it will eventually set but it takes a long time. On occasion I've mixed too much and put the excess in the freezer to use later. Next day it's ok, but a week later it's set up hard. Also the mechanical properties might not be as good if it sets up too slow or too fast. On critical items temperature is important. Many epoxy formulations come with different "speed" hardeners. Use the one appropriate to your environment of the day even if it means stocking two or three different types.

The results were actually contrary to that. The remaining epoxy that was left on the cardboard was almost hard after 24 hours while the epoxy in the holes was still very soft.

[Boatyarddog]

Originally Posted by tronic72

The results were actually contrary to that. The remaining epoxy that was left on the cardboard was almost hard after 24 hours while the epoxy in the holes was still very soft.

This is because the amount of the epoxy was comparatively small, and the "work" was cold.
Had you used a heat lamp it would have been dramatically different.
You must warm the Work first.
As the cardboard is a bit of an insulator the remainder of your epoxy retained enough of its self made chemical heat to kick faster.
Epoxy cures in stages.
Boatyarddog

[bullislandken]

Originally Posted by Spot

Double nod...Isopropyl (rubbing) alcohol and citrus soaps will also clean epoxy up before it sets/cures. Acetone is not preferred, it is said to break down the epoxy to a point where it is readily absorbed into the skin thus aggravating any exposure or allergy risks.

I discovered the vinegar or uncured epoxy by accident. And it isn’t presented in the epoxy manuals. I should check Russell Brown’s. I clean tools and even brushes so easily…cheaply….and safely?? Could it also make the toxins from epoxy a greater dermal hazard? I think I heard it breaks down the hardener.

[sea-bee]

Originally Posted by tronic72

The results were actually contrary to that. The remaining epoxy that was left on the cardboard was almost hard after 24 hours while the epoxy in the holes was still very soft.

Maybe the thinner less viscous hardener soaked into the cardboard, leaving the remaining resin not properly mixed.

[coopec43]

Originally Posted by Boatyarddog

Should ask the question WHY chemically resistant gloves are not being used working with Acetone Or Epoxy.
Just looking for trouble and reactions to the stuff.
West systems has some different hardeners as well.
Don't touch the stuff much, and remove it from skin.
Another trick is Vaseline rubbed on hands if not using gloves.
It creates a barrier that keeps the epoxy away from skin, and comes off easier.
Boatyarddog

I'd be very careful when using some of the chemicals used in fiber-glassing but I don't think acetone is particularly dangerous. (Your body produces acetone in breaking down fats)

Can I dip my fingers in acetone?

If there's one thing you don't want to do to your nails or your skin, it's soaking them in acetone. Soaking your nails for long periods to break down nail polish or gel is far from ideal, and can cause some serious irritations. Acetone can dehydrate the nail bed, cuticles, and skin.

https://www.google.com.au/search?q=h...client=gws-wiz

PS I use one of my Wife's discarded hair dryers on "hot" to warm up the epoxy in cold weather

[longjonsilver]

Originally Posted by Spot

Nice. I thought read somewhere that 10 degrees F /5 degrees C is a factor of 2 for cure times. So it the epoxy was designed for lab temp 77F / 25 C then 67 F 20 C will take 2x as long and 87 F 30C would be 2x as fast.

Not sure about the specifics of epoxy, but as a general rule in chemistry a 10C increase in temperature results in a halving of the reaction time.

[alanrothenbush]

Originally Posted by tronic72

Hi, I filled a heap of holes yesterday and came back today to find the holes in varying degrees of hardness (or softness).

I did the same thing about a month ago, filled some holes in my little Boston Whaler. A number of items were fastened to the hull simply using wood screws into the upper fiberglass layer.

I used the same procedure as I'd done dozens and dozens of times before to my sailboat over the last 20 years or so.

I started by drilling the holes significantly oversized, and then undercutting with a custom tool.

Then I weighed out the material on a small digital scale. Getting an ACCURATE 2:1 ratio with small quantities is tough, but getting a 100:44 ratio or 100:48 with the cold cure is easy if you weigh it.

(BTW, an uncle of mine was one of the inventors of 2 part epoxy, when he was a chemist working for .. Dupont?.. IIRC. He gave me some words of wisdom. He told me that as the ratio of hardener to resin gets bigger, the strength of the epoxy goes up, which makes sense, as it's the resin that gives the strength. So 2:1 is stronger than 1:1 and 5:1 is stronger still.

BUT, as the ratio grows, so does the need for accurate mixes. 1:1 would probably work as well as it's going to if mixed 2:1. But 5:1 mixed 5.5:1 might have less than half its strength.

So I stick with System 3 2:1, rather than West 5:1, and also take the trouble to weigh it.)

Continuing my tale, I mixed in some filler, again, as I had dozens of times in the past, and filled the holes.

A day later, I fully expected it to be hard, given that the daytime temps were in the 70s and night time maybe as low as 60. I noticed no change.

A week later, it had STARTED to set, the littlest bit, maybe.

A MONTH later, it still hadn't set, it remained a sticky mess of "oatmeal".

I still had the original mixing pot around, so I took a heat gun to it to warm it. It DID warm up, no question, but never set.

I mixed up another batch, being VERY careful about the mix. A week later in warmer weather still, it hadn't set.

So I just tossed out about $100 worth of epoxy and started on the HORRIBLE task of COMPLETELY removing the unset epoxy; the holes still had to be filled.

Now, the epoxy was about 4 years old and had gotten pretty cold a few times, temps down to 20 or so.

However, the manufacturer's website stated that neither should be a problem, cold storage isn't an issue, neither does it "age". So I don't know what happened.

But I do have a new process; I'll buy smaller quantities and I'll fire up a test batch before doing something where failure would be .. bad.

[Bloodhound]

Originally Posted by Spot

Nice. I thought read somewhere that 10 degrees F /5 degrees C is a factor of 2 for cure times. So it the epoxy was designed for lab temp 77F / 25 C then 67 F 20 C will take 2x as long and 87 F 30C would be 2x as fast.

That’s true for most (but not all) chemical reactions. Factor of 2 per 10F (C?) temperature change.

[Rumrace]

I don’t know of an Epoxy brand you can store below freezing. I’m pretty sure it will cause a poor mix.

[alanrothenbush]

Originally Posted by Rumrace

I don’t know of an Epoxy brand you can store below freezing. I’m pretty sure it will cause a poor mix.

System 3 says to store above 50 degrees F or it might crystallize. But if it does, heat it up in warm water (or a microwave!) until the crystals go away.

But I have found two different statements on age. One says the shelf life is indefinite if stored in the original containers with lids tightly closed. The other, that I JUST found, says "we only guarantee it for three years, test it if it's older than that."

Wish I'd read that second statement a month ago ...

[Jammer]

Originally Posted by Rumrace

I don’t know of an Epoxy brand you can store below freezing. I’m pretty sure it will cause a poor mix.

WEST system epoxy isn't affected by freezing.


https://www.westsystem.com/the-105-s...ge-shelf-life/

[Rumrace]

Plastics are changing to quick for me to pretend I’m an expert on any plastic. I’ve used Systems West for ever.
More due to 3D printing in exotic materials way stronger than Epoxy like PEEK CF. It fuses at 420c on my printer. Any variant or even a gust of cold air and the print is garbage. 3D filaments resins and powder are very fragile until put to use. Moisture absorption a killer freezing turn many into junk. Other than alarge hull repair I’ve bought Systems West in the poverty pack two can 3 pumps accessory. Use it in the next few months and immediately after opening. From the minute you expose poly or vinyl to the air the clock is ticking. Even a can of micro balloons can absorb moisture and cause burn bubbles.
Vacuum bagging Epoxy hulls usually results in a great hull but massive waste in Epoxy.
I’ve also painted a few cars bikes and one boat with two part DuPont with slow going pearl. It’s a base clear but the pearl load slows the cure like carbon fibre. Adding hardener will burn it. - Orange peel can’t win

[Rumrace]

Sorry PS
Always buy the pump kit with Systems West. The pumps prevent moisture absorption as well as give proper mix.
THey extend the usable life of Systems West.