<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"> <html> <head> <meta http-equiv="Content-Type" content="text/html;charset=ISO-8859-1"> <title></title> </head> <body text="#000000" bgcolor="#ffffff"> <div class="moz-text-plain" wrap="true" graphical-quote="true" style="font-family: -moz-fixed; font-size: 13px;" lang="x-western"> <pre wrap="">Just today I had the same thing happen to me, only my batch was only 1 pump of each and I was using a 6 oz. plastic cup. I had made my repairs and then returned to the cup after 5-10 min. and the mixture was already hardened. It was still warm and had caused the cup to wrinkle. I was beginning to wonder if my materials had gotten beyond their shelf life. I have used West Systems epoxy numerous times before (sometimes larger batches) without this happening and yet, recently, I have noticed that my mixing cups were wrinkled as if by heat when I returned, maybe days later. The only difference I am aware of is the size of the cup. 10 0z. cup - no problem. 6 oz. cup - it gets hot. Maybe there is another variable I am not aware of. John Voigt Assoc. Avon, SD <blockquote type="cite"><div class="moz-text-plain" wrap="true" graphical-quote="true" style="font-family: -moz-fixed; font-size: 13px;" lang="x-western"><pre wrap="">List, I had an interesting experience with epoxy the other day, so I thought I'd post my situation as well as the response from West System. It helped me and may help others who are not as familiar with the use of epoxy. Just started working on some finger worn keys, following the method posted by Ed Foote some time back. Basically it involves using West System A group epoxy, 105 Resin and 206A hardener as well as 410 microlite fairing. I mixed up some epoxy, four pumps each into a 2oz. plastic cup, added a bit of fairing to thicken, and about 10 minutes into ladeling the mixture onto the keys, the mixture began to smoke in the cup it was in. It had been slowly gaining heat the whole time. I set it down, and the whole thing just solidified within about 3-5 minutes. I mixed a fresh batch, same result. Then I mixed another a bit thinner (less fairing), [and in retrospect, only two pumps] and didn't seem to have any trouble this time. What's going on? Response from West System: <<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<< The more mass that is mixed, the faster the product cures. Also, the longer the product is contained the faster it cures. Ambient heat also accelerates the cure (for every 20F increase in temperature, pot time halves). The cure mechanism/energy produces heat - exothermic. 4 pumps of each is a lot of material and the time it takes to blend in #410 Microlight to a thick consistency in a container with little surface area, plus the ambient heat from your hand holding the pot is sufficient to produce a run-away exothermic condition. Suggest mixing less - 2 pumps each and after blending resin/hardener together spread out into a shallower pot when blending #410 - increased surface area extends working time. </pre><blockquote type="cite"><blockquote type="cite"><blockquote type="cite"><blockquote type="cite"><blockquote type="cite"><blockquote type="cite"><blockquote type="cite"><blockquote type="cite"><blockquote type="cite"><blockquote type="cite"><blockquote type="cite"><blockquote type="cite"><blockquote type="cite"><blockquote type="cite"><blockquote type="cite"><blockquote type="cite"><blockquote type="cite"><blockquote type="cite"><blockquote type="cite"><blockquote type="cite"><blockquote type="cite"><blockquote type="cite"><blockquote type="cite"><blockquote type="cite"><blockquote type="cite"><blockquote type="cite"><blockquote type="cite"><blockquote type="cite"><blockquote type="cite"><blockquote type="cite"><blockquote type="cite"><blockquote type="cite"><blockquote type="cite"><blockquote type="cite"><blockquote type="cite"><blockquote type="cite"><blockquote type="cite"><blockquote type="cite"><blockquote type="cite"><blockquote type="cite"><blockquote type="cite"><blockquote type="cite"><blockquote type="cite"><blockquote type="cite"><blockquote type="cite"><blockquote type="cite"><blockquote type="cite"><blockquote type="cite"><blockquote type="cite"><blockquote type="cite"><blockquote type="cite"><blockquote type="cite"><blockquote type="cite"><blockquote type="cite"><blockquote type="cite"><pre wrap=""><span class="moz-txt-citetags">>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>></span> </pre></blockquote></blockquote></blockquote></blockquote></blockquote></blockquote></blockquote></blockquote></blockquote></blockquote></blockquote></blockquote></blockquote></blockquote></blockquote></blockquote></blockquote></blockquote></blockquote></blockquote></blockquote></blockquote></blockquote></blockquote></blockquote></blockquote></blockquote></blockquote></blockquote></blockquote></blockquote></blockquote></blockquote></blockquote></blockquote></blockquote></blockquote></blockquote></blockquote></blockquote></blockquote></blockquote></blockquote></blockquote></blockquote></blockquote></blockquote></blockquote></blockquote></blockquote></blockquote></blockquote></blockquote></blockquote></blockquote><pre wrap=""> Ed also pondered the idea of a cold bath/wrap to extend the working time, and this seems to support that idea. Hope this helps some folks. William R. Monroe Madison, WI Assoc. </pre></div></blockquote> </pre> </div> </body> </html>