[OP]
Member
I often have a need to thin epoxy, and I've always used Xylene. It works, but it's a little hard to mix as it doesn't dissolve too easily.
Today at the Borg I happened to read the label on a can of M.E.K. and it also says 'for thinning epoxies." Has anyone used both? Any idea which is easier to use?
Also, any idea if one or the other results in a stronger bond? I've always wonder about strength-loss. Maybe the one that evaporates the fastest is best?
Member
I have used small amounts of acetone before. A little bit has an appreciable effect on viscosity. I think it also degrades strength too, but I dont know if acetone is better or worse than Xylene
Member
West System recommends using heat to thin epoxy, as solvents compromise strength and cause other issues.
http://www.westsystem.com/ss/thinnin...-system-epoxy/
Gerry
JointCAM
Contributor
Turners often us epoxy thinned with DNA (denatured alcohol) to strengthen punky wood when turning.
Ken
So much to learn, so little time.....
Contributor
[OP]
Member
Originally Posted by Gerry Grzadzinski
Wow, that's good info.
Thanks.
Member
Whats the application that requires thinned epoxy?
Member
I you decide to go the MEK route, wear a respirator. At work we called it "Methyl Ethyl DEATH".
"When the horse is dead, GET OFF."
Guest
I think you want latex gloves, not nitryl? I know acetone goes through nitryl.
MEK works very well with gelcoat, I haven't used it with epoxy. The gelcoat I use is a vinylester resin.
Member
Acetone is fairly low in toxicity, especially compared to xylene or MEK.
Member
Epoxies don't harden/cure by evaporation of their solvent. It cures by a thermal process. In other words a couple of the chemicals interact producing heat and its the heat that causes the curing action.
As to your question, I strongly suggest you contact the manufacturer. They can tell you the chemicals the can be used as a thinner. You really don't want to guess at it if you are truly looking for maximum strength.
Howie.........
Contributor
Warming certainly works and it doesn't take much. Last winter I put too-thick-to-use System3 5 minute epoxy in warm - by no means hot - water for a few minutes. It flowed nicely but 5 minute epoxy became about 3 minute epoxy as far as pot life.
Member
Methanol or isopropyl alcohol work well to thin epoxies too Allan, at least on coatings where i've used them extensively. Even 5 - 10% has a big effect on viscosity. They flash off a lot more slowly than would acetone. Epoxies don't need teriibly strong solvents.
I'd avoid MEK if i could.
I'd be cautious about thinning epoxies if they are required to cure in the solid/through any significant thickness or in an enclosed space as the chances are that the solvent will be trapped as a result of not flashing off fast enough and the resulting polymer would likely be quite a lot weaker.
Warming in the pot/dish after mixing and just before use is probably the plan in the caase of an adhesive or filler. Use a slower curing version to achieve decent pot life with the heat.
Fumed silica or micro balloons (don't breathe either in) can be used to thicken it, but at the expense of making it opaque/to a fair degree taking on the colour of the filler...
Last edited by ian maybury; 10-15-2015 at 8:11 AM.
Member
I've used xylene to thin epoxy for stabilizing woodrot with great success. I've seen pieces after 10 years in the sun and rain and they are still good. As far as mixing, I put the 2 part epoxy along with the xylene in a plastic glue bottle with a screw-on tapered tip. I hold a gloved finger over the tip and shake it until well mixed (while wearing a respirator of course). This also makes it easy to apply it where I need it, and if it starts to heat up and catalyze before I use it all, a new bottle is only 50 cents or so.
I got the tip on using xylene from Paul Oman, the Progressive Epoxy guy. I've never tried MEK with epoxy.
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