Re: Is glass etching a physical or chemical change?

Armor Etch chemically removes glass and sandblasting physically removes
glass.  The surface left behind by either process is still glass but is
physically changed in appearance.  It is pitted by the Armor Etch or pitted
and/or scratched by sandblasting.  The differing methods of removal may
result in a different look or feel of the surface produced but that is a
physical difference and not due to a chemically different surface remaining
after the etching.  Most chemical etching products contain some chemical or
combination of chemicals that can give Fluoride ions in solution.  A look
at “Common Sources for Various Chemicals” on the Society of Amateur
Scientists (SAS) website reveals that in the case of Armor Etch the active
ingredient is Ammonium Bifluoride  (NH4HF2).  As with any material that can
produce significant amounts of  either Fluoride ions or Hydrogen Fluoride
(HF) you will of course want to scrupulously follow all safety precautions.