help please with engraving glass?

[Rodney Gold]

Glass does not laser engrave nicely , what happens is the laser thermal shocks it and the engraving is actually an uncontrolled micro fracture. Laser engraving always has a shattered effect.

Overpowering or using higher dpi actually is WORSE if you bear this thermal shock and crack thing in mind.So the first thing I would do is drop dpi to 300 or so and then reduce power a bit. The 2nd strategy is to use moistened bog roll on it and laser thru that (we found paper better and add in about 10% dishwashing liquid) Do not use a lot of air assist when doing this a it tends to blow the paper away. makes sure the paper stays moist. A lot of guys use a mask on the glass and laser thru it and then sandblast , this type engraving is wonderful , the best of both worlds , the lasers detail and the sandblasted finish.
Once the glass is engraved you need to scrub it with a piece of scotchpad etc to “de chip” it , but this often leaves ugly “bare” patches if the engraving isnt so hot. We normally also put white Rub ‘n buff paste into the engraving and then take off the excess with paper towels etc and this whitens the engraving substantially
Rub ‘n buff or gilders wax (silver gilders works well too) is available at craft shops. Its very durable in the engraving too and withstands dishwashers.
I imagine you are using a rotary attachment to your laser , if not you will have not much success when the glass slopes , power and speed are pretty critical with glass.
We often just spread some slightly diluted diswashing liquid on and let it dry and find that alone works , we have also lasered thru masking tape and found the engraving smoother , a lot depends on the glass itself. For example you can cut stained glass with a laser and not clear , its cos of the pigments in the stained and how they reac to the lasers thermal shock. Cheap glasses laser best , bottles are variable as they often contian pockets of impurities and different mixes of glass. Lead crystal is a very risky thing to laser as it often shatters.
For your application , using a paper based vinyl application tape as a mask or resist and lasering thru that on the glass and buying a small hobbyist blaster with very fine grit will do you fine and really allow you the quality to let your glass engraving take off. The paper resist will withstand a blast. You could offer 2 prices , laser or “sandcarved” …. sandcarving SOUNDS like it gonna be an expensive and artistic process 😉 – So charge!!!!

[Vitor Brito]

Thx again Rod
As usual this men really knows is business, unvaluable to this forum and for me particularly.

I’ll try some of your solutions a.s.a.p.

Altough some of them i can’t try them before this particular job, they all seem very useful, and i’ll try them surely.
(The only problem is i have done a small research in Portuguese distributors for the small blaster and i couldn’t found one satisfactory yet, soo i might have to import it directly if i decide to go that way, and that means without having chance to try it before, but i’ll keep asking for it for a while before goin forward.)

Thx
Vitor Brito