It's Alive part II - Shellac?

[C. E. Hood]

Early piano makers sometimes use shellac (pretty thin mix) to brighten hammers, the Viennese kind which are layers of leather stretched & glued over the core.  I understand that this was done in early times.  Any comments?  Haven't tried it on felt, but it will soak in as far as you want, it can be re-softened & thinned in situ by adding alcohol solvent; if the surface is scratchy & clangy, scritch it a bit with a knife blade.
  Best, Margaret