Reversion of PU coatings was a serious issue during the VietNam conflict. Brian joyce wrote: > Being said all the good thing about silicone, I believe few years ago, > there is a dissociation of silicone (reverse polymerization) under some > specific solvent/RH related condition (oil based, If I remember > correctly). As long as someone fully understand the application, you > will select a good coating for environmental protection. Otherwise, > there is no "one coating fits all" stuff... May be some grad student > should start a PhD thesis on that... > > jk > > >>-----Original Message----- >>From: TechNet [mailto:[log in to unmask]] On Behalf Of Brian Ellis >>Sent: Monday, September 08, 2003 10:31 AM >>To: [log in to unmask] >>Subject: Re: [TN] Silicone conformal coating >> >> >>Of course silicone will repel liquid water, but we are talking >>here of water in a gaseous phase and my experience is that it >>passes small molecules, such as water, like a sieve. In the >>former case, it is a question of the high surface tension of >>water, but single molecules, ata a time, have no surface, >>therefore no surface tension. >> >>Brian >> >>Misner, Bruce wrote: >> >>>Brian, >>> >>>This diaphram experiment does not take into account the surface >>>wettability of Silicone which is supposed to be one of its major >>>protective features (according to Dow) which precludes surface >>>droplets from forming. Comments? >>> >>>Thanks, >>>Bruce Misner >>> >>> -----Original Message----- >>> From: Steve Gregory [mailto:[log in to unmask]] >>> Sent: Monday, September 08, 2003 8:54 AM >>> To: [log in to unmask] >>> Subject: Re: [TN] Silicone conformal coating >>> >>> In a message dated 09/05/2003 2:03:30 AM Central Daylight Time, >>> [log in to unmask] writes: >>> >>> >>> >>>> I thought I had reported the details of this in >>>> my book, but could not find them today. Must have been >>> >>somewhere >> >>>>else. >>> >>> >>> >>> Hi Brian! >>> >>> It is in your book, on page 329, at the bottom of the >> >>section where >> >>> you talk about Silicone Elastomers. >>> >>> In your book you state that you made a diaphram of >> >>silicone that was >> >>> 5mm thick, and 100mm in diameter. On one side the air >> >>was held at 40 >> >>> degrees C., and 95% RH, the other side at 5% RH. There was 1g of >>> water vapor per day allowed to pass through the silicone >> >>diaphram. >> >>> You stated that is 40 times worse than epoxies, and 20 >> >>times worse >> >>> than polyurethanes. >>> >>> Do you have any idea about arcylics? >>> >>> Regards, >>> >>> -Steve Gregory- >>> --------------------------------------------------- >>> Technet Mail List provided as a free service by IPC >> >>using LISTSERV 1.8e >> >>> To unsubscribe, send a message to [log in to unmask] with following >>> text in the BODY (NOT the subject field): SIGNOFF Technet >>> To temporarily halt or (re-start) delivery of Technet >> >>send e-mail to >> >>> [log in to unmask]: SET Technet NOMAIL or (MAIL) >>> To receive ONE mailing per day of all the posts: send e-mail to >>> [log in to unmask]: SET Technet Digest >>> Search the archives of previous posts at: >>> http://listserv.ipc.org/archives >>> Please visit IPC web site >>> http://www.ipc.org/contentpage.asp?Pageid=4.3.16 for additional >>> information, or contact Keach Sasamori at [log in to unmask] or >>> 847-509-9700 ext.5315 >>> ----------------------------------------------------- >>> >>>--------------------------------------------------- >>>Technet Mail List provided as a free service by IPC using LISTSERV >>>1.8e To unsubscribe, send a message to [log in to unmask] with >> >>following >> >>>text in the BODY (NOT the subject field): SIGNOFF Technet To >>>temporarily halt or (re-start) delivery of Technet send e-mail to >>>[log in to unmask]: SET Technet NOMAIL or (MAIL) >>>To receive ONE mailing per day of all the posts: send e-mail to >>>[log in to unmask]: SET Technet Digest >>>Search the archives of previous posts at: >>>http://listserv.ipc.org/archives Please visit IPC web site >>>http://www.ipc.org/contentpage.asp?Pageid=4.3.16 for additional >>>information, or contact Keach Sasamori at [log in to unmask] or >>>847-509-9700 ext.5315 >>>----------------------------------------------------- >> >>--------------------------------------------------- >>Technet Mail List provided as a service by IPC using LISTSERV >>1.8e To unsubscribe, send a message to [log in to unmask] with >>following text in the BODY (NOT the subject field): SIGNOFF >>Technet To temporarily halt or (re-start) delivery of Technet >>send e-mail to [log in to unmask]: SET Technet NOMAIL or (MAIL) >>To receive ONE mailing per day of all the posts: send e-mail >>to [log in to unmask]: SET Technet Digest Search the archives of >>previous posts at: http://listserv.ipc.org/archives Please >>visit IPC web site >>http://www.ipc.org/contentpage.asp?Pageid=4.3.16 for >>additional information, or contact Keach Sasamori at >>[log in to unmask] or 847-509-9700 ext.5315 >>----------------------------------------------------- >> > > > --------------------------------------------------- > Technet Mail List provided as a service by IPC using LISTSERV 1.8e > To unsubscribe, send a message to [log in to unmask] with following text in > the BODY (NOT the subject field): SIGNOFF Technet > To temporarily halt or (re-start) delivery of Technet send e-mail to [log in to unmask]: SET Technet NOMAIL or (MAIL) > To receive ONE mailing per day of all the posts: send e-mail to [log in to unmask]: SET Technet Digest > Search the archives of previous posts at: http://listserv.ipc.org/archives > Please visit IPC web site http://www.ipc.org/contentpage.asp?Pageid=4.3.16 for additional information, or contact Keach Sasamori at [log in to unmask] or 847-509-9700 ext.5315 > ----------------------------------------------------- > > --------------------------------------------------- Technet Mail List provided as a service by IPC using LISTSERV 1.8e To unsubscribe, send a message to [log in to unmask] with following text in the BODY (NOT the subject field): SIGNOFF Technet To temporarily halt or (re-start) delivery of Technet send e-mail to [log in to unmask]: SET Technet NOMAIL or (MAIL) To receive ONE mailing per day of all the posts: send e-mail to [log in to unmask]: SET Technet Digest Search the archives of previous posts at: http://listserv.ipc.org/archives Please visit IPC web site http://www.ipc.org/contentpage.asp?Pageid=4.3.16 for additional information, or contact Keach Sasamori at [log in to unmask] or 847-509-9700 ext.5315 -----------------------------------------------------