I have been seeing a good deal about this category of sealants, but am only beginning to get into the subject. The literature promotes them as having the best of the silicone and organic (urethane and polysulfide) products.
Does anyone have any words of wisdom (including horror stories) and suggestions for manufacturers other than BASF?
Polyethers seem to have been a flash-in-the-pan. I used them back in the late 90’s when I first heard of them but never found them to actually perform as well as silicones. The only possible benefit for using them seemed to be that joint surfaces don’t need to be as pristine for the sealant to bond properly. I don’t know if polyethers have the same reversion problems as urethanes.
I stopped using polysulfides years ago. At the time that Morton dropped out of the market, the formulas for the remaining polysulfides were so badly compromised that it seemed foolish to even consider that genre as an option.
I know that some silicone manufacturers dabbled in polyethers and found no benefit. Not one opted to come out with product lines. Seems to me that if it was such a great thing more people would have jumped on the bandwagon.
I had an opportunity to use a polyether sealant on a project in my home recently and found it to be quite satisfactory where I had used a silicone previously that had failed. York is carrying it in their product line and I believe it has promise.
I haven’t seen polyethers in a spec or used in years - as earlier mentioned, they seemed to be the “flavor of the month” for a while and then were gone.
I generally stick with single or plural-component urethanes and use silicones only in reglazing projects.
There’s a running joke among contractors that silicones should only be sold with a specific weapons permit - they seem to be used most often as crack fillers, causing unnecessary (and very expensive) problems for building owners when repairs need to be redone correctly…
The urethanes simply do not hold up as well as the silicones. I am told that this is because manufacturers have downgraded or removed a lot of the UV-resistant stuff making them more prone to breakdown due to UV-related oxidation. In the Houston area (and I think this is true for much of the country), you will see them use to seal the joints in tilt-up work. I understand the caveat about using them as crackfillers, but I would prefer using them for joints exposed to the exterior in exterior wall assemblies.