I lucked out with a sympathetic salesman, who sent a 'free evaluation sample' - about five gallons! So you have to mix it about one part silicate to about three parts water - so I have a big supply. You have to mix in water because it carries the silicate into the substrate. This is basically 'liquid silica sand' which reforms into very fine silica crystals. There is a book called Painters Handbook by Mark Gottsbergen, it has a long section on fresco and he tries out all the other silicates except potassium. I recommend this book though - you should be able to get it from a library in Phoenix.

This silicate is used extensively to make high strength concrete. There are small quantities available from kremer-pigmente.com It turns out that potassium silicate is the solution to the 'lost' sound of stradovarias violins.

It is remarkable stuff, has no smell, but is high alkaline. The wierdest discovery was when I was mulling pigments and silicate on a piece of frosted glass. Some of it dried overnight and it had bonded to the glass (another form of silica sand) so hard that I could only sand it off.

The key is apply enough to protect the wall but not so much that you get a glossy buildup - this, again is an experience thang.