Silyl-Terminated Polyether

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Author Message Anonymous   Posted on Tuesday, March 22, 2005 - 07:29 pm:    Resisted the sales onslaught for years but after hearing from other spec writers in the area about it and no negative reports, began specifing Silyl-Terminated Polyether sealant for exterior, non-trafficked joints. This sealant is sold and advertised as a paintable sealant with movement capability similar to silicone, at less cost. Just went through weeks of investigation stemming from painter's claims that high quality latex paint was not adhering to sealant. Throughout this period of time, manufacturer's technical rep and local rep insisted that this had never happened, that problem must be something other than sealant. Final determination after conducting on-site paint application demonstration with local rep present is that paint not adhering well to properly installed sealant joints. No explanation provided by manufacturer's rep. No further investigation offered by manufacturer's rep. Silyl-Terminated Polyether sealants terminated alright, straight out of my specification. anon [I am not fond of negative Anonymous postings, but I thought the questions raised here were worth discussion and to have a possible manufacturer response. Colin] Marc C Chavez Senior Member Username: mchavez Post Number: 92 Registered: 07-2002 Posted on Tuesday, March 22, 2005 - 08:03 pm:    I have been specifing the product for several years. In every case, however, painting was not a problem so it has not come up. I'll send a note to the polymer manufacturer and see what they have to say. John Bunzick, CCS, CCCA Senior Member Username: bunzick Post Number: 336 Registered: 03-2002 Posted on Wednesday, March 23, 2005 - 08:55 am:    Marc, Is this because the sealant wasn't painted? or because it painted acceptably? Do you know what kind of paint was used? Marc C Chavez Senior Member Username: mchavez Post Number: 93 Registered: 07-2002 Posted on Wednesday, March 23, 2005 - 11:10 am:    We did not paint it at all. With the use of the 40 different colors available we were able to avoid the issue (probably because we have been working around it for years) George A. Everding, AIA, CCS, CSI Senior Member Username: geverding Post Number: 24 Registered: 11-2004 Posted on Wednesday, March 23, 2005 - 12:34 pm:    From a manufacturer's (Sonneborn) website: "Sonolastic® 150 can be painted over after a thin film or skin forms on the surface. When painting over any elastomeric sealant, use a paint that is also elastomeric. (If movement occurs, the paint will also move.) An alternative to painting is applying Sonolastic® 150 Tint Base in one of its standard colors." This reinforces John's question about type of paint used, and Marc's work-around of tinting, not painting. Just because a sealant is advertised as "paintable" doesn't mean all paints will work. Anonymous   Posted on Wednesday, March 23, 2005 - 01:20 pm:    Manufacturer claims (and has claimed for years) that any paint is acceptable/compatible and admitted to me that the data sheet is in error in stating that only elastomeric coatings are acceptable, and that it would be corrected. Their selling point for this product is that it performs like silicone, but in addition can be painted! The issue at hand, however, is not the coating's ability to move with the sealant, but adhesion to the sealant. Movement is an issue with ALL paintable sealants. We expect the latex coating to move less than the sealant below it. Rep was on hand for the paint application demonstration and could offer no explanation as to why the paint was not adhering to properly applied and cured sealant. This was especially vexing because for weeks the manufacturer insisted that the sealant was not the problem. When it became evident that the sealant was the problem, a deafening silence was all the manufacturer could offer. I like the product, but will not specify it any longer as a paintable sealant when there are tried and true products available that are paintable. Kenneth C. Crocco Senior Member Username: kcrocco Post Number: 20 Registered: 04-2003 Posted on Thursday, March 24, 2005 - 08:52 am:    Why do you prefer to paint sealants? I presume you are talking about exterior sealants. I've looked at 100's of buildings over the years and the color of the sealant is not a critical factor, in my opinion, even custom color sealants, especially after weathering. For appearance we depend on the neatness of installation and tooling, close color match using sealant's integral color, and lack of staining.