Section 10: Material Engraving Techniques
105
Glass
Glass Background
When a laser strikes glass it fractures the surface but it will not engrave deeply or
remove material. The fracturing of the glass surface will produce a frosted
appearance but can cause roughness and chipping depending on the type of glass
being engraved. While the frosted appearance is desired the roughness and chipping
are not. Below, we explain how to eliminate the roughness and produce a very
smooth frosted finish.
The composition and quality of glass varies widely and you cannot always predict the
effect that you will achieve. It is always best to experiment with an unfamiliar glass
source. Generally speaking, flat glass tends to have a very consistent hardness
throughout, and the engraved areas do not tend to have lighter and darker areas.
Bottles on the other hand, tend to have soft and hard spots that will cause the
engraved area to appear lightly frosted in one area and heavily frosted in another.
Engraving at medium speed and high power will somewhat compensate for this, as
will two or more engraving passes.
While the laser beam itself is very hot, the heat does not build up easily and it should
not prevent you from engraving onto full bottles of vine, champagne or other filled
glass bottles. Laser engraving filled bottles is a very popular method of creating
custom presentations for special occasions. The laser will not damage the liquid
inside the bottle, and as long as you are not completely engraving away a large
section of bottle you have very little chance of breaking the bottle.
Glass Engraving Techniques
To produce a smooth frosted finish, follow this procedure:
¾ Using your finger or a paper towel, apply a thin coat of liquid dish soap – any kind will
do – over the area to be engraved.
¾ Cut a piece of newspaper or paper towel a little larger than the area to be engraved.
Completely soak the paper with water then wring out the excess water.
¾ Apply the paper to the glass and smooth out the paper so that there are no wrinkles.
¾ Place the glass into the engraver and laser through the paper while it is still wet.
¾ Remove the glass, discard the remaining paper, and clean the glass.
¾ If necessary, gently polish the glass with a ScotchBrite pad.