Thinning epoxy with Xylene?

Again, after finishing my Wood Duck 10 hybrid last spring, I am working on a wood RC model.  The instructions suggest thinning the finishing epoxy with Xylene to avoid air bubbles coming from the bare wood


Since I never had to thin my epoxy while working on the kayak, I'm not sure I need to do it for this model boat.  Anybody have experience with this?





9 replies:

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RE: Thinning epoxy with Xylene?

I would steer clear of xylene.  It is EXTREMELY toxic and you need to handle it with great care.  The best way to keep bubbles from forming is to heat up the room you are building in, apply the epoxy, and then let the room cool as the epoxy cures.  This way the wood will not be outgassing causing bubbles to form.  

RE: Thinning epoxy with Xylene?

When building RC airplanes, and using epoxy and .75 oz cloth, we would thin the epoxy with denatured alchohol. It would only take a few drops to get really runny. It would soak into the balsa wood alot deeper than unthinnned epoxy. It also takes longer to set up, the alchohol has to evaporate before the epoxy can recombine. Good luck.

RE: Thinning epoxy with Xylene?

Based on the response, I definitely will not use Xylene.  Since the side and bottom planking is balsa(which I have never worked with), the denatured alcohol idea sounds good.

Thanks to Casey and "JNC" for your advice.


RE: Thinning epoxy with Xylene?

I used to thin epoxy with lacquer thinner once in awhile, for penetrating coats.  The epoxy manufacturers don't want you to do it.  When I did it anyway, about 1 in 4 thinned epoxy treatments didn't cure properly.  Not recommended for man-rated vessels...

We keep some xylene around the shop for getting stickers off cars and boats.  I can't think of any other non-industrial use for that nasty stuff.

RE: Thinning epoxy with Xylene?

In fact, the maximum allowed workplace levels in the US for Xylene and Toluene (the major component of at least one lacquer thinner brand) that I saw are both the same:  100 ppm. (Although I saw some variation, from 50 to 200, between different government agencies and time periods)

Lacquer thinners have different amounts of different chemicals from one brand to the other. 

Yes, all of these volatile organic compounds (there are many of them...methyl ethyl ketone, methanol, etc.)  have toxic fumes. MEK for example has allowed levels in the same ballpark as xylene and toluene (REL of 200 ppm from both OSHA and NIOSH)

Yes, you should wear a cannister-type respirator (they are fairly cheap and quite comfortable) when using any of them, limit exposure time, and avoid using them indoors. (Exception:  Personally, I don't worry about denatured alcohol fumes, though I admit I didn't look that one up)

But I saw no facts to support the idea that xylene is remarkably toxic compared to lacquer thinner.

RE: Thinning epoxy with Xylene?

You could use a different epoxy that's thinner to begin with. I've used System 3 for clear coats and it's definitely thinner than West System and both were thinner than some others I've used.

RE: Thinning epoxy with Xylene?

It's amazing how much I have learned using the builders' forum!

For the RC model project, I am using Mas rein and hardener left over from my wood duck build.

I researched a bit more and found that epoxy manufacturers don't recommend thinning.  One company suggested heating the resin and hardener prior to mixing to lower the viscosity.  That sounds to me like it will do the trick.

Thanks again for helpful advice/info.


P.S.  If you want to see the boat I am building, search MACK products and Jersey Speed Skiff.  It is a gorgeous model.  Sorry I don't have the web site

RE: Thinning epoxy with Xylene?

Bad stuff. Dispose of properly!

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