Linda, The darkening of the HumiSeal 1A33 that you are seeing is due to the oxidative cross-linking mechanism of the resin. In many ways, this is a good thing, since it shows that your product is fully cross-linked, and hence the full properties of the 1A33 coating have developed. I have not heard of anybody having reliability concerns regarding 1A33 - indeed it is used extensively in many hostile environments, where it's superior chemical resistance is beneficial. I do not have any reliability data for the 1A33 - I think you'd need to approach someone building similar boards for similar environments as yours, to get some comparative data. Have you tried HumiSeal direct? Jim Lawrence [log in to unmask] is usually a good source of information. Best Regards, Phil Kinner Chief Chemist Please note that Concoat has recently acquired the former Multicore SPCID business. For more information, please visit our new web site www.concoatsystems.com Concoat Ltd Alasan House, Albany Park, Camberley, Surrey, GU16 7PH Tel: +44 (0) 1276 691100 Fax: +44 (0) 1276 691227 ----- Original Message ----- From: Linda Woody To: [log in to unmask] Sent: Wednesday, May 22, 2002 8:24 PM Subject: [TN] TypeUR conformal coatings I am currently using a type UR (Humiseal 1A33) conformal coating which has been shown to discolor over time and temp. Granted all UR's discolor over time, but this one seams to be worse than others (Conathane 1155). The 1A33 is QPL approved and is very producible (no bubbles, very little T/U rework) Is anyone out there using Humiseal 1A33? And what if any feedback or data can you provide on reliability of this material as a conformal coating. Appreciate any info Thanks Linda Woody Lockheed Martin Missiles and Fire Control --------------------------------------------------------------------------------- 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 e-mail to [log in to unmask]: SET Technet NOMAIL 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/html/forum.htm for additional information, or contact Keach Sasamori at [log in to unmask] or 847-509-9700 ext.5315 ---------------------------------------------------------------------------------