Has anyone used one of the many kits available for applying spray foam to surfaces to insulate them?  Any ideas on which ones might be better or any brand to stay away from?  We're remodeling an old farm house with a rock foundation and I've patched up the mortar the best I can and now I'm thinking about applying a layer of spray foam on it to try to seal it up to any small cracks that might still let in some air in the winter.

  Just wondering if any certain brand is better than the next.

TIA,

Steve