Epoxy Thinner?

Moose Masher

Moose Masher

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In the latest issue of "Rifle" there is an article on fixing cracked stocks. The author describes thinning Acraglass and painting on the end grain, letting it soak into the wood to prevent future cracking. He suggests using Brownells Acraglass Thinner. Does anyone know if Acraglass Thinner is available in Canada, and can it be shipped? Is there another product that can be used to thin Acraglass or Acraglass Gel that will not affect the integrity of the epoxy?
 
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I prefer heating it under a light bulb and warming the wood the same way... it gets very runny and sets up quick after the heat is removed...
 
guntech said:
I prefer heating it under a light bulb and warming the wood the same way... it gets very runny and sets up quick after the heat is removed...
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This works well. I have never used the Acraglass, but 24hr laminating epoxy gets very thin and runny if you heat it. Note that heating it will accelerate the pot life and curing time, so plan ahead and don't get caught short on time.

If you don't want to heat it, acetone or isopropyl alcohol will thin epoxy. Do a test batch first, sometimes the epoxy will end up rubbery and not cure hard when thinned.

Mark
 
mmattockx said:
This works well. I have never used the Acraglass, but 24hr laminating epoxy gets very thin and runny if you heat it. Note that heating it will accelerate the pot life and curing time, so plan ahead and don't get caught short on time.

If you don't want to heat it, acetone or isopropyl alcohol will thin epoxy. Do a test batch first, sometimes the epoxy will end up rubbery and not cure hard when thinned.

Mark
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Isopropyl alcohol may thin the reagents but it will also enter the chemical reaction taking place. The isopropyl alcohol has a single alcohol group that can displace a di- or polyfunctional "alcohol" precursor in the reaction mixture. This will lead to incomplete polymerization and result in a rubbery product.
 
If you thin epoxy with a solvent like acetone it (the acetone) must be able to evaporate before the epoxy starts to harden so in an enclosed area or a thick layer it is not a good idea. Heat works very well to make epoxy runny but of course also speeds the cure. I have never tried isopropyl but I will just to see what it does to epoxy. I imagine it would tend to thin the hardener part more than the resin part, but then maybe that's what Gun5 said. The rubber is sure correct. My father was a chemist, too bad he's not still around, I could have put him to work!
 
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Ian Robertson said:
If you thin epoxy with a solvent like acetone it (the acetone) must be able to evaporate before the epoxy starts to harden so in an enclosed area or a thick layer it is not a good idea. Heat works very well to make epoxy runny but of course also speeds the cure. I have never tried isopropyl but I will just to see what it does to epoxy. I imagine it would tend to thin the hardener part more than the resin part, but then maybe that's what Gun5 said. The rubber is sure correct. My father was a chemist, too bad he's not still around, I could have put him to work!
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To make a polymer each component must have two or more reactive groups on the component molecules. An epoxide is a precursor to a molecule with two alcohol groups ( a diol) on neighboring carbon atoms. By adding a monoalcohol like isopropyl alcohol it can take the place of the diol and cause the polymerization to be incomplete. You could just get a sticky mess that will neither harden nor evaporate.
 
I have used acetone to thin epoxy (W.E.S.T epoxy or Ind. Formulators I can't remember/over 15 years ago) when finishing stocks and it worked great...It is my understanding you can buy a thinner type of epoxy these days...Contact Industrial Formulators (Vancouver area)for more info... Cold Cure is a low-viscosity epoxy that should work well...Lee Valley Tool carries it......

Cold Cure Epoxy Adhesive........................................................................
The most versatile of our epoxy systems, Cold Cure is a waterproof structural bonding agent and penetrating sealer. It will cure at temperatures down to 2°C/35°F, even under water. Cure time varies with temperature; at 20°C/70°F it is 24 hours.
A low-viscosity epoxy with good wettability. It can be used on wood, metal, plastic, porous or non-porous surfaces, as an adhesive, sealer or laminating resin. A two-part system, 2:1 ratio.

Made in USA.



A. Cold Cure, 355ml (12 fl oz)
56Z74.05 $31.50

B. Cold Cure, 710ml (24 fl oz)
56Z73.00 $46.80




Home Woodworking Gardening Hardware Gifts
(2)
© Copyright 1998 to 2009 by Lee Valley Tools Ltd. and Veritas®Tools Inc. All rights reserved.
 
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I've used thinned epoxy on a number of occasions. BUT ONLY IN THIN SURFACE COATS where the thinner will evaporate. I would not thin it and pour it into a crack. Epoxy and polyester resins (regular fiberglass) cure rather than dry. Adding a thinner to it and then shoving it into a crack where the thinner is no longer exposed to the air is a good way to really mess up the proper chemical reaction that is going on just as mentioned above.

I've always seen it written that for epoxy you use isopropyl alchohal and for epoxy you can use acetone. Or lacquer thinner since it's mostly acetone anyway. In my case and with using a painted on application resulting in a thin film the alchohal evaporated just fine and the epoxy cured up in pretty much the proper time.

However for sealing and stabilizing a crack I would only heat it to a runny consistency and use that. Also heat the stock as well so the wood is warm to further let the epoxy pentrate. Put the wooden stock in the oven at around 150F or 70'ishC so it warms up without getting hot enough to char the wood or the finish. You just want it warm enough that you can still comfortably hold it but it's getting pretty close to too hot. There's no need or point to going any hotter. Wood is a great insulator though so let it soak at this warming temp for a good hour before you pour in the epoxy. The epoxy can be warmed up in the same oven but for a lot less time. A far better way is about a minute before you remove the stock from it's hour long bake is to set the mixed epoxy in a tin into a hot water bath. The water should be well up there and just about boiling. Stir until it's gotten all watery and then remove the stock from the oven, mask off any runout paths quickly with masking or duct tape and then pour in the epoxy slowly giving the air at the bottom of the groove time to run to the side and come out. For the same reason fill from one end so again the air gets pushed out by the incoming glue.
 
Thanks on the tip on "Not" to use acetone thinned epoxy for fixing cracks BCrider...
You probably saved my some grief down the road as I have 3 cracked stocks that need repair...When I did use acetone thinned epoxy it was for finishing / weather proofing the stock exterior and it worked very well for that..
Thanks again
 
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