<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN"> <HTML><HEAD><TITLE></TITLE> <META http-equiv=Content-Type = content=text/html;charset=ISO-8859-1> <META content="MSHTML 6.00.2900.2180" name=GENERATOR> <STYLE></STYLE> </HEAD> <BODY text=#000000 bgColor=#ffffff> <DIV><FONT face=Arial size=2>Hi John,</FONT></DIV> <DIV><FONT face=Arial size=2></FONT> </DIV> <DIV><FONT face=Arial size=2>There's a somewhat fine line, short of = which it takes forever for the stuff to cure, and beyond which the stuff goes thermonuclear.  When I'm using the stuff, I mix it in a small = plastic cup (6 oz, I'd guess).  If the ambient temperature is a bit cooler, = perhaps at or below 70F, I can mix up two or even three pumps without the = mixture quickly "flashing."  However, for this to work, the cup needs ventillation.  Do NOT cover the cup, or it will flash quite = rapidly.  (Covering it doesn't do anything useful anyway.)  If I'm working at = a moderate to higher ambient temperature, only one or two pumps can be = used.  If you're working with the stuff, and it's getting warm in the cup, it = won't be long before it hardens.  To slow the process, cool the = mixture.  I do this by spreading the mixture over the walls of the cup with my = spatula.  With more surface area, the mixture will lose heat faster.  = Finally, I *think* I'm correct that fillers hasten the cure, I suspect because they = help to insulate the mixture.</FONT></DIV> <DIV><FONT face=Arial size=2></FONT> </DIV> <DIV><FONT face=Arial size=2>If you want a longer pot life, put a = fan by the cup.  If you want the ultimate pot life, put the cup in some cool = water (not cold enough to create condensation on the inside of the cup).  = Cool epoxy will take forever and a day to cure.  I know this from having = done hull repair on a boat during cold weather.  :-(  If your workpiece is warm, it will speed the curing once the epoxy is = applied.  To speed curing further once applied, cover it to protect it from = drafts.  Be careful if you have too much of it in too well insulated a space, = though.  I'm pretty sure the stuff could catch something on fire under extreme conditions.  If in doubt, use the 209 hardener, as Terry suggested.</FONT></DIV> <DIV><FONT face=Arial size=2></FONT> </DIV> <DIV><FONT face=Arial size=2>Peace,</FONT></DIV> <DIV><FONT face=Arial size=2>Sarah</FONT></DIV> <BLOCKQUOTE dir=ltr style="PADDING-RIGHT: 0px; PADDING-LEFT: 5px; MARGIN-LEFT: 5px; = BORDER-LEFT: #000000 2px solid; MARGIN-RIGHT: 0px"> <DIV style="FONT: 10pt arial">----- Original Message ----- </DIV> <DIV style="BACKGROUND: #e4e4e4; FONT: 10pt arial; font-color: = black"><B>From:</B> <A title=jvoigt@gwtc.net href="mailto:jvoigt@gwtc.net">John = Voigt</A> </DIV> <DIV style="FONT: 10pt arial"><B>To:</B> <A = title=pianotech@ptg.org href="mailto:pianotech@ptg.org">pianotech@ptg.org</A> </DIV> <DIV style="FONT: 10pt arial"><B>Sent:</B> Tuesday, September 21, = 2004 8:11 PM</DIV> <DIV style="FONT: 10pt arial"><B>Subject:</B> Re: epoxy fun</DIV> <DIV><BR></DIV> <DIV class=moz-text-plain lang=x-western style="FONT-SIZE: 13px; FONT-FAMILY: -moz-fixed" = graphical-quote="true" wrap="true"><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 lang=x-western = style="FONT-SIZE: 13px; FONT-FAMILY: -moz-fixed" = graphical-quote="true" wrap="true"><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: <<<<<<<<<<<<<<<<<<&= lt;<<<<<<<<<<<<<<<<<&l= t;<<<<<<<<<<<<<<<<<&lt= ;< 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>>>>>>>>>>>>>= >>>>>>>>>>>>>>>>>>&= gt;>>>>>>>>>>>>>>>>>&g= t;>>>>>></SPAN> </PRE></BLOCKQUOTE></BLOCKQUOTE></BLOCKQUOTE></BLOCKQUOTE></BLOCKQUOTE></= BLOCKQUOTE></BLOCKQUOTE></BLOCKQUOTE></BLOCKQUOTE></BLOCKQUOTE></BLOCKQUO= TE></BLOCKQUOTE></BLOCKQUOTE></BLOCKQUOTE></BLOCKQUOTE></BLOCKQUOTE></BLO= CKQUOTE></BLOCKQUOTE></BLOCKQUOTE></BLOCKQUOTE></BLOCKQUOTE></BLOCKQUOTE>= </BLOCKQUOTE></BLOCKQUOTE></BLOCKQUOTE></BLOCKQUOTE></BLOCKQUOTE></BLOCKQ= UOTE></BLOCKQUOTE></BLOCKQUOTE></BLOCKQUOTE></BLOCKQUOTE></BLOCKQUOTE></B= LOCKQUOTE></BLOCKQUOTE></BLOCKQUOTE></BLOCKQUOTE></BLOCKQUOTE></BLOCKQUOT= E></BLOCKQUOTE></BLOCKQUOTE></BLOCKQUOTE></BLOCKQUOTE></BLOCKQUOTE></BLOC= KQUOTE></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></BLOCKQUOTE></BODY></HTML>