Author Topic: Best Epoxy for strength and fumes  (Read 6494 times)

Beasho

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Re: Best Epoxy for strength and fumes
« Reply #15 on: March 22, 2017, 02:45:57 PM »
It never dawned on me to use a gram scale to weigh out small batches.

I turned to gram scales years ago.  With Resin Research the ratio is 55 parts by weight to 45 parts Resin vs. Hardener. 

If you really want to whip up small batches e.g. 5 or 7 or 10 grams at a time you should buy a gram scale that measures to the 1/100th of a gram.  Use a plastic spoon to catch and then pour the fine droplets.  Each drop is ~ .07 grams.  I keep a spoon in a bag with the Resin and a bag with the hardener.  Just don't mix them up. 

Perfect batches every time. 

supuk

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Re: Best Epoxy for strength and fumes
« Reply #16 on: March 22, 2017, 02:46:15 PM »
super sap is defiantly more smelly than RR. its wets out slightly better but takes longer to cure and not as workable.  Surf clear was similar to super sap but didn't sand as well ether.

PonoBill

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Re: Best Epoxy for strength and fumes
« Reply #17 on: March 22, 2017, 03:16:49 PM »
Beasho, you've got me confused. Resin Research 2100 is 100 parts resin to 45 parts hardener by weight, 2 to 1 by volume. I use 10 to 4.5 to make it easy. 20 grams of resin, 9 grams of epoxy. If you start using a scale, be sure to use one that has a Tare button so you can re zero with the cup on the scale.

When I get a new batch of cups I weigh a few of them so I know more or less what they weigh--all will generally be within a tenth of a gram--then I note that on the bag that holds the cups. With my shit memory, I'm constantly losing track of what I'm doing, taking the cup off the scale before adding hardener and forgetting how much resin I have. You'd think I'd only do that once, but I did it this morning. If you know the weight of the cup you can weigh the whole thing and know how much resin you have. Then push the Tare button and weigh your hardener.
Foote 10'4X34", SIC 17.5 V1 hollow and an EPS one in Hood River. Foote 9'0" x 31", L41 8'8", 18' Speedboard, etc. etc.

Beasho

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Re: Best Epoxy for strength and fumes
« Reply #18 on: March 22, 2017, 04:07:08 PM »
Beasho, you've got me confused. Resin Research 2100 is 100 parts resin to 45 parts hardener by weight, 2 to 1 by volume. I use 10 to 4.5 to make it easy. 20 grams of resin, 9 grams of epoxy.

You are correct.  My memory failed, other than the 45 part.  Here is the cheat sheet I attach with clear packaging tape on my larger Resin bottle so that I don't forget.  Good tip on weighing the cup.  I typically tare the cup out.  But that would help in a bind.

The benefit of the incremental batches is that you can match the batch to the weight of your patch.  For carbon layups this can result in very strong composites (good for fixing broken carbon fiber paddles by the way).  Typically you want 1:1 but leaning towards LESS Resin than the weight of the fiberglass.  I think a good carbon ratio was 2:1 Cloth to Resin ~ 66% to 33% by weight. 
« Last Edit: March 22, 2017, 04:14:09 PM by Beasho »

blackeye

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Re: Best Epoxy for strength and fumes
« Reply #19 on: March 22, 2017, 10:57:10 PM »
DO NOT USE ACETONE with epoxy. Alcohol cleans it up fine or better yet, use disposable stuff.

Why not acetone? Other than the correlation to sensitivity? I have used Acetone, outside, as I have a big jug of it. Also, I use gloves and know not to get it on skin.

What kind of alcohol do you recommend?

And to the general audience, absence of aroma in any substance doesn't necessarily mean more safe. Especially in a basement and if the fumes settle and concentrate or displace/consume oxygen.

jrandy

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Re: Best Epoxy for strength and fumes
« Reply #20 on: March 25, 2017, 01:56:10 PM »
Blackeye, you pose some interesting questions.

Yes, because something is bad does not mean is has to look or smell bad. I think the questions about a respirator and venting are valid too.

The Wikipedia article on 'epoxy' is pretty good and notes some of the health hazards of the resin and hardener components of epoxy.

I think the 'rub' with acetone is that it takes the reactive pieces of the epoxy mix and allows them to be more readily absorbed into the air and into the skin.

For me, it's disposable gloves, mix containers, and brushes. Cleaning up small spills while wet is with 91% isopropyl alcohol (drugstore not denatured) and cleaning up the small bits on my wrists and forearms is with 'orange' type soaps with pumice, also before it gets sticky. Squeegees get one wipe with paper towel while wet and the rest is cracked off once cured.

For mixing, I use a scale and a calculator. When I am on the ball, I write down the tare weight of the container and my 'ideal' mix weights for resin and hardener. Then as I (usually) overshoot with the resin I redo the math for the hardener and drip-drip-drip it in once I am close to avoid having to re-add resin to fix the mix.
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Be safe, have fun. -J

jpeter

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Re: Best Epoxy for strength and fumes
« Reply #21 on: March 25, 2017, 07:28:18 PM »
You can get big plastic syringes for measuring smaller amounts.   and keep them full to be ready for the next time.
JP

Fanman

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Re: Best Epoxy for strength and fumes
« Reply #22 on: March 27, 2017, 05:24:04 PM »
Thank you for all the input.

My NY Glassing room is ready!

I can't take credit for glassing that one, Terance Brandt in HB.

Thx, FM

 


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