FAQ from the manufacturer...
A: We [the manufacturer] consider anything larger
than 1"x1" too large for solid etching.
Armour Etch is NOT made to etch
solid large areas of glass. It is stated
in all of our instructions and books. It
is impossible to evenly coat a piece of glass all at the same time. Therefore, wherever you apply the Armour Etch
to first will start to etch immediately upon contact. The brush will leave brush strokes and the
trail of where you etch first, then second, etc, will show up in the end
results.
Also, when glass is manufactured
sometimes stains occur due to the type of process used to make the glass. We do
not see these stains because we are looking through them. When you etch the
glass, these stains become visible as Armour Etch is only creating a surface
etch, which is not deep enough to go past this
stain.
In some cases, certain window
cleaner can create a stain on the glass. Especially the cleaners that
advertise a reduction in fingerprints. These cleaners are actually putting
a coating onto the glass, thus eliminating
fingerprints.
If you take a piece of scrap
glass and place you finger onto this glass firmly you will leave a fingerprint.
Paint the Armour Etch over your fingerprint, wash off the etch, dry
completely.... and you will see that the finished end results will be blotchy
where you placed your fingerprint.
Therefore, it is extremely
important that the glass you are etching is completely clean and free of lint,
dirt, fingerprints, window cleaner residue, etc.
The only way to etch glass SOLID
and have professional looking results, is to Sand Blast the glass or
mirror.