We have inventigated by measuring contact-angles of water and linseed oil on zinc plate whether the zinc plate, counter-etched, will become hydrophilic or hydrophobic.
Counter-etched by “alum and nitric” we have proven zinc plate becomes well wet either with water or with oil because the surface area of the plate increases. Chemically, however the surface property of the plate, becomes hydrophilic.
The zinc plate counter-etched by acetic acid gives almost no increase of the surface area and so the contact-angles change only a little. It is not clear whether the surface property becomes hidroplilic or hydrophobic with an application of acetic acid.
It is considered an absorbtion film of acetic acid is formed on the surface.