Edison Coatings wrote: > > I am just a chemical engineer > And I am just a guy that gets to play with stuff. I agree that control of water flow through maintenance of gutters, leaders, roof systems etc. is way more of a factor in the deterioration of brownstone facades than coatings. Though I really am solidly against the wholesale use of cut-n-stucco techniques. I have encountered situations, one in particular, where the sandstone (not brown in this case) was coated so many times by maintenance staff that it was the coating that held the stone together. Once the coating was removed the stone crumbled, whereas everywhere else on the facade where maintenance could not conveniently reach the stone was in noticeably better, though admittedly poor, condition. So, I would prefer appropriate maintenance if it is to occur at all. In my experience though knowledge is not very well communicated to maintenance. Which brings up questions as to how knowledge of anything gets disseminated into the built environment. Many times experts are not brought in to see evidence in the field as there is no motivation to involve them -- then the question is how do they learn? > If you don't have tons of water pouring into the wall system, letting > it out just isn't that big a deal. > Yeah, all you need is good flow, a few well placed holes. > > ...they just aren't seeing the predicted damage. DUH! But hey, don't > acknowledge those of us who questioned the conclusions on this > subject 25 years ago. > I agree with your sentiment re: the back-n-forth on clear coatings. It is curious to me that a quarter century can go by and yet there is no conclusive consensus. One expert doctor will say it is good to beat children, another expert doctor will say that it is not. Personally I find the lack of consensus, and the constant reiteration of pro and con to be the more interesting subject. I remember a time when to say 'abrasive blasting' was suicide and that was when I was playing with plastic media to remove epoxy paint from granite at Carnegie Hall. Then came micro-abrasives and soda blast and all sorts of chummy stuff. ][<en -- To terminate puerile preservation prattling among pals and the uncoffee-ed, or to change your settings, go to: <http://listserv.icors.org/archives/bullamanka-pinheads.html>