This sounds like sodium silicate (or a similar silicate salt), a water soluble material that has long been used as a surface sealant.  It is widely used to protect concrete surfaces.  Chemical toxicity is minimal.  Silicosis should not be a problem as long as the material remains reasonably soluble after application -- it will self-dissolve in the body.<p><a href="http://en.wikipedia.org/wiki/Sodium_silicate" rel="nofollow">http://en.wikipedia.org/wiki/Sodium_silicate</a>