Doug, Shame I am not included in Graham's "Coating Room work naked bonus" - but merely trapped away in my office! I should say that blushing is almost exclusively humidity related. The cooling effect caused by the atomisation of the solvents causes condensation of the excess humidity. The rate of evaporation of the solvent will probably affect the degree of effect though... (did I get those the right way round?) Switching to a solvent such as 2-pentanone (MPK) which is a) more volatile than say xylene, and b) is probably a weaker solvent for say an acrylic could potentially cause worsening of any blushing, bubbling in the coating and cobwebbing (weaker solvent = higher solids content at low spray viscosity). Let us know how you get on. Best Regards, Phil Kinner Concoat Ltd -----Original Message----- From: TechNet [mailto:[log in to unmask]] On Behalf Of [log in to unmask] Sent: 19 July 2001 13:38 To: [log in to unmask] Subject: Re: [TN] White residue from conformal coating Graham, Thanks for the insights on the "blush" phenomena. How interesting that it comes up in the same discussion as your "work naked bonus". Is there any link between the type of solvent in the coating and blush, or is it exclusively humidity related? One project that has been suggested for me is to replace the toluene and xylene we use as acrylic thinners with methyl propyl ketone. If such a switch were made, would you expect a greater or lesser susceptibility to blush, or is it immaterial (no pun intended). Doug Pauls Rockwell Collins ------------------------------------------------------------------------ --------- Technet Mail List provided as a free service by IPC using LISTSERV 1.8d 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 delivery of Technet send the following message: SET Technet NOMAIL Search previous postings at: www.ipc.org > On-Line Resources & Databases > E-mail Archives Please visit IPC web site (http://www.ipc.org/html/forum.htm) 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 1.8d 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 delivery of Technet send the following message: SET Technet NOMAIL Search previous postings at: www.ipc.org > On-Line Resources & Databases > E-mail Archives Please visit IPC web site (http://www.ipc.org/html/forum.htm) for additional information, or contact Keach Sasamori at [log in to unmask] or 847-509-9700 ext.5315 ---------------------------------------------------------------------------------