<html> <head> <META HTTP-EQUIV="Content-Type" CONTENT="text/html; = charset=us-ascii"> <meta name=Generator content="Microsoft Word 10 (filtered)"> <style>  </style> </head> <body lang=EN-US link=blue vlink=purple> <div class=Section1> My formula recently has been the System Three epoxy colorant.  This is a stiff, opaque paste, designed to work with = epoxy resins.  Two cautions:  The color slows the hardening time considerably, renders the epoxy less brittle, and too much will prevent = it from hardening altogether. (at least on a non-geologic time scale).  = Also, the color tends to weaken bond strength and the epoxy’s ability to = flow and expel air.  I usually start with a batch of clear epoxy to wet the = crack and fill to the bottom.  I have used them with West Systems resin = and slow hardener, and I would assume they work fine with System Three’s = own products.   I have purchased the paste in yellow, brown, and most importantly, white.  I believe they also make red, which would = probably be handy in tiny amounts to “orange” up the mix.  Just = adding the colors makes too deep a saturation long before the desired level of = opacity is reached, so start with white.  With a semi-translucent white base, = much less of the deeper colors are needed.  Experiment with how much, but = less is definitely better.  I add the smallest amount of paste necessary to = do the job.  A batch that won’t cure would be a real disappointment, = and I disclaim all responsibility for such an outcome.   Even with the color, this stuff will migrate.  I = have come within an inch or so of the end of a crack that diminished to zero = width, and have had it wick to the very end.  It does tend to trap air = bubbles, so be careful mixing and actively squeegee it in over its entire pot life.  Tapping the board at intervals seems to = help.   The photo shows an unfinished board with two filled cracks.  As was mentioned earlier, check color against a wet board = for a closer match.  These did match quite well when = finished.   Like many others on the list, I’m not trying to = make cracks disappear, or pretend they never happened.  But they should = still be pretty to look at with all your plate work, shiny pins, and that = expensive decal.  If making them somewhat attractive really weren’t an objective, we’d color them blue!     David V. Anderson, RPT Waukesha, WI   </div> </body> </html>