Return-Path: Received: from www.laf.oceanenergy.com ([206.97.189.62]) by truman.olsusa.com (Post.Office MTA v3.5.1 release 219 ID# 0-52269U2500L250S0V35) with ESMTP id com for ; Tue, 16 Mar 1999 18:13:57 -0500 Received: by OEINT_LAF1 with Internet Mail Service (5.5.1960.3) id ; Tue, 16 Mar 1999 17:10:23 -0600 Message-ID: From: "Westphal, D. (Dana)" To: "'lancair.list@olsusa.com'" Subject: Re: How hard is hard? Date: Tue, 16 Mar 1999 17:10:15 -0600 X-Mailing-List: lancair.list@olsusa.com Mime-Version: 1.0 <<<<<<<<<<<<<<<<--->>>>>>>>>>>>>>>> << Lancair Builders' Mail List >> <<<<<<<<<<<<<<<<--->>>>>>>>>>>>>>>> >> I too have encountered inconsistencies with my epoxy pump. This is evident by the variation in color of the epoxy mixture which has typically erred on the too dark (too much hardener) side. I had once thought that this may be due to the changing color of the 2 parts (the hardener seems to darken) as it ages somewhat (good for wine, but not for structural glues, huh?). I have yet to realize a soft or uncured batch. I have also observed that the larger batches appear to be more consistent and figured it was the result of "statistical averaging", e.g., the first stroke too much hardener dispensed, the second stroke too little, and the next 5 or so fairly correct with the final, total batch being about right. For small batches I always use my scale (don't want that inaccurate first pump stroke to make up 50% of my total volume) and try to select the final weight (volume needed), and thus each part's weight to mitigate any round-off and/or resolution inaccuracies of the scale and my calculations. I have found my weighed batches, especially the larger ones, to be very consistent, as they always seem to start setting up (flashing) at about 20 minutes in the hot summers of southern Louisiana. Of course I use a stop watch to keep close tabs on how much time I have left. I recall reading once that a qualitative test is to scratch the surface of the unused, "cured" epoxy mixture with a sharp knife - the epoxy should feel hard and yield a nice "crisp", "white" and shallow scratch line. As a side note, I am a new subscriber to LML and the "volumes" have been a great source of info and have served to "pump me up". The monthly periodicals I subscribe to help, but the almost daily "posts" have a more immediate impact. Keep up the great work, Marv, and forgive me if I messed up the "format" with my first submittal! Dana Westphal 360 MKII (finishing horizontal stab) Dana L. Westphal Reservoir Engineering dwes@oceanenergy.com [Your post looks great, Dana, no problems at all. Looking forward to seeing many more in the future from you. Thanks, ]