Heat and epoxy

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silentneko
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Heat and epoxy

Post by silentneko » Mon Apr 22, 2019 12:23 pm

So we all know that cured epoxy can soften with heat, but what about when the heat is gone? Is the epoxy permanently damaged, or does it reharden?


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jacquesmm
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Re: Heat and epoxy

Post by jacquesmm » Mon Apr 22, 2019 12:35 pm

It becomes hard again.
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silentneko
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Re: Heat and epoxy

Post by silentneko » Mon Apr 22, 2019 12:50 pm

Awesome.

The reason I ask is I have become a big fan of heating my wood parts (cleats, brackets, hatch lip...) prior to neat coating/epoxy priming them. It makes a huge difference, instead of the resin pooling on the surface it gets pulled deeper into the wood. On occasion I'm adding a cleat or neat coating a part that is secured prior to glassing the rest and just wanted to make sure I'm not permanently damaging anything.
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OrangeQuest
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Re: Heat and epoxy

Post by OrangeQuest » Mon Apr 22, 2019 1:10 pm

Interesting idea.
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Re: Heat and epoxy

Post by jacquesmm » Mon Apr 22, 2019 1:19 pm

I have to check that. Some heat in the sun is one thing (that was my reply) but deliberately heating the resin may have other effects.
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Re: Heat and epoxy

Post by joe2700 » Mon Apr 22, 2019 3:30 pm

In the TDS for silvertip epoxy there is a "Heat Deflection Temperature" of 128°F and a "Maximum Service Temperature" of 160°F.
https://cdn.shopify.com/s/files/1/1000/ ... 2554198805

I read that as it gets soft above 128°F and could be permanently damaged above 160°F. I also remember the post cure temperature for silvertip being 140°F but I can't find the source for that. If you are using a different epoxy I would find the TDS from the manufacturer to find out what temps are safe.

silentneko
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Re: Heat and epoxy

Post by silentneko » Mon Apr 22, 2019 3:36 pm

140 or 160 degrees is more then enough. I'm just heating it so it's warm to the touch. I've read that to be most effective you should heat a surface to about 30 degrees above ambient temp. If I had to guess I would say I'm maybe around 120 degrees or so.
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Re: Heat and epoxy

Post by joe2700 » Mon Apr 22, 2019 3:42 pm

You should be safe then if you are using silvertip. Whenever I am doing the first layer of glass over bare wood I also raise temperature and let it drop as I work. End up with no bubbles as the wood is trying to pull the resin in as you say.

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OrangeQuest
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Re: Heat and epoxy

Post by OrangeQuest » Mon Apr 22, 2019 4:13 pm

Yes, I would think the cooler liquid epoxy will cause the surface temps to drop as soon as it starts touching it unless you are heating the wood for a few hours in a oven where more than the surface is heated up.

Just me guessing out loud. :doh:
"that it isn't just an ordinary sort of boat. Sometimes it's a Boat, and sometimes it's more of an Accident. It all depends." "Depends on what?" "On whether I'm on the top of it or underneath it."
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Re: Heat and epoxy

Post by OrangeQuest » Mon Apr 22, 2019 4:15 pm

Now I have been epoxying outside in sunlight and the wood is being heated up and got bubbles due to the wood still being heated.
"that it isn't just an ordinary sort of boat. Sometimes it's a Boat, and sometimes it's more of an Accident. It all depends." "Depends on what?" "On whether I'm on the top of it or underneath it."
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