Engraving on Mirrors

[Carol Stopforth]

Hi, can anyone give me some advice on engraving on the back of mirrors. I have tried various settings but either the laser eats off too much of the mirror backing, or else it doesn't engrave deep enough to show through on the front side. Is there "rule of thumb" settings for engraving on mirrors? I have a 60w CO2 engraver. Any advice will be appreciated.

[Tim Bateson]

Nope/None..... I have done a number of mirrors & the only thing for certain is they are all different. The thickness of the mirrored material on the back seems to differ a lot. If you don't have an extra mirror (identical to the one you are going to use), start on the low side of the power range and make multiple passes until you have achieved what you are looking for.

I assume from your statement you are trying to produce more than a 1 bit image? Not possible on a mirror. However, the dot placement can give you the allusion of tones.

Do you have an example (photo) of your issues you can post?

[Mark Ross]

Some people use a wet paper towel to reduce the heat on the mirror. Some people use a water and/or water/dishsoap solution. Tim is right, every mirror is different. I have gone to Walmart and purchased two identical mirrors only to get them apart and in the laser and I found one had a weird copper color to the backing and the other was a dull grey.

You cannot have your DPI set too high because if you do, you are trying to fire too many dots too close together and the mirror material simply blasts completely off.

Also, in my attempts (and we cut a ton of acrylic mirror) I have never had any luck getting good resolution on acrylic mirror. Glass I have been sucessful at.

[Joe Hillmann]

What do you mean,"it eats off too much of the backing"? Do you mean once it is through the backing it engraves into the glass or do you mean that it burns or flakes off at the edge of where you were engraving?

[Dave Sheldrake]

Remember Carol, Polarised RF lasers give different results to un-polarised Chinese DC tubes. Also backscatter from glass mirrors can damage lens's if they don't have anti reflective coatings both sides.

best wishes

Dave

[Martin Boekers]

After watching some You Tube videos, I have started to use the standard masking for glass and crystal. It works great!
Much better than the JDS Tape and easier to remove. Some of the better mirrors have coated metal on the backside, that
you will not go through. Stick with cheap mirrors. :D

[Bill Cunningham]

Some mirror will engrave nicely, others hardly at all. The hardly at all class, seems to be a metallic coating. I have a type here that etches well, but smells exactly like burning gunpowder.
Also, some backings are water soluble so careful with the soap and wet paper.

[Mark Ross]

The ones I have done from Wally World that work well and smell like burning gunpowder seem to be copper colored and metallic. But like I said, you can go in and buy the exact mirror, get the back off and find that it is one of those non-engraveable types.