On Tuesday 11 February 2020 20:17:12 dave engvall wrote: > I like the idea of iso-propanol. The only thing that would improve the > process is vapor degreasing. The trick of a non-filled epoxy as a > primer is good. Why didn't I think of that. ;-) > > The Navy uses acetone for degreasing before using loc-tite on their > nuclear stuff. Degrease, blow dry, add primer, insert fastener. Who > know what grade of acetone they use ... probably analytical grade. ;-) > Or the really fancy stuff for pesticide residue analysis. > > Please understand...if I'm not careful I can learn something everyday. > > Dave > > On 2/11/20 4:38 PM, Bruce Layne wrote: > >> On Tue, Feb 11, 2020 at 10:30 AM Gene Heskett > >> <ghesk...@shentel.net> > >> > >> wrote: > >>> Cleaned up with acetone of course. > > > > Cleaning with acetone will result in a good epoxy bond. Cleaning > > with isopropyl alcohol will result in an excellent epoxy bond. > > Commercial acetone, at least in the US, is recovered from industrial > > processes. It's distilled, but a trace amount of the waste oil > > remains in the acetone after the distillation process and will leave > > a slight oily film on your parts after the acetone evaporates. It's > > not enough to feel or see, but it's enough to prevent the best > > possible epoxy bond. > > > > Maybe remove most of the oily gunk with acetone, scrub with 60-100 > > grit sandpaper to create a rough surface for the epoxy to grab, then > > flood with isopropyl alcohol to thoroughly degrease the part prior > > to applying epoxy. I'll sometimes use a clean blue paper shop towel > > or toothbrush with the alcohol at first if some physical scrubbing > > is still needed. I'll finish the job with a spray bottle with > > isopropyl alcohol to blast off the last traces of oil, allowing the > > alcohol and suspended oil to drip off the part, and then I don't > > touch the part with my bare hands. You've made your own printed > > circuit boards and the process is similar to the final step of > > cleaning the bare copper board before the etch resist process. When > > the board is clean of oxides and oil free, the solvent will > > uniformly wet the board, drip off the bottom edge, and the board > > will dry from the top down leaving a matte finish. > > > > Pro Tip: for the very best bond when using a filled epoxy, first > > paint the bare surface with a thin layer of raw epoxy (resin and > > hardener) before applying the filled epoxy (such as JB Weld). The > > unfilled epoxy can more easily penetrate the fine scratches on the > > substrate, and the filled epoxy then binds to the unfilled epoxy. > > That's a tip from people who build composite fiberglass airplanes. > > I used to clean video tape heads with freon-tf, several times a day. Got boring. Ran out of tf, so switched to paint thinner grade alky from Ace Hdwe. Noticed I was only doing it maybe weekly. Never went back to tf. My contribution to closing the ozone hole at the south pole. > > > > > > > > _______________________________________________ > > Emc-users mailing list > > Emc-users@lists.sourceforge.net > > https://lists.sourceforge.net/lists/listinfo/emc-users > > _______________________________________________ > Emc-users mailing list > Emc-users@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/emc-users
Cheers, Gene Heskett -- "There are four boxes to be used in defense of liberty: soap, ballot, jury, and ammo. Please use in that order." -Ed Howdershelt (Author) If we desire respect for the law, we must first make the law respectable. - Louis D. Brandeis Genes Web page <http://geneslinuxbox.net:6309/gene> _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
