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Sonny Mounicou
06-10-2011, 9:18 PM
So my first post and a quick question for the experts. I'm planning to laser etch some granite that I picked up to make a headstone. I'm concerned because the surface is reflective because its polished (and has some marbling). Should I be concerned with laser etching a polished surface or will it be fine? My concern is of course reflecting the laser back into the beam/mirrors and creating an issue.

For additional information, this is a vl200 25 watt laser cutter. The material is a piece of black marbled 2" thick countertop granite.

Thanks in advance!

Chuck Stone
06-10-2011, 10:13 PM
If you mask the surface, the reflection won't be an issue. Even regular masking tape would
work in a pinch, but transfer tape is better.

Sonny Mounicou
06-10-2011, 10:40 PM
So just put some transfer tape on the top and cut through it? Do I need to up the power or lower the speed? Will the tape at the link below work? I plan to etch a photograph along with text.

Richard Rumancik
06-10-2011, 10:45 PM
As soon as the beam hits the stone, it will cause particles to ablate and the surface will turn rough. Any further energy will probably just be dispersed in random directions as it will no longer be a reflective surface. I don't think you will have a problem. If you wish to mask you will have to increase power a bit. But I think quite a few people engrave granite without masking.

Dee Gallo
06-10-2011, 11:51 PM
I've done a few photo/text combo granite tiles that were polished and never masked them. Maybe Bill will check in here, he has a lot of experience with stone and photos.

:) dee

Sonny Mounicou
06-11-2011, 10:44 AM
Thanks for the responses everyone. I'm going to give it a shot today and see how it goes. Now I'm just having a tough time finding the right font :) I'll update this thread with my settings and pictures once I'm done.

Dan Hintz
06-11-2011, 11:42 AM
There are two items working in your favor:
1) There's a difference between substrates that are reflective in the visible wavelengths (what our eyes see) and non-visible wavelengths (such as the near-IR wavelength of the CO2 laser)
2) The surface is not as reflective as you think it is... sure, it looks polished, but it's reflecting a very small amount of light (particularly at the wavelength of the laser).

Bill Cunningham
06-11-2011, 8:40 PM
Masking is a waste of time, and not needed.. If the stone has a lot of large quartz fleck in it, it won't render photos as well as small or no fleck.. The picture below is probably close to the maximum fleck there can be before the photo starts to degrade.. As Richard said above, there is no problem with beam reflection. After tweaking your photo to what pleases you, and gives you the best results on your machine (practice/practice/practice), use the 'generic' granite setting on photograv if you use photograv..

197746

Frank Corker
06-12-2011, 6:18 AM
I too have engraved a lot of granite. You will not encounter any problems with reflection and the engraving will be fine. The only issues you might encounter with granite is the 'flecks' inside the rock, naturally formed there is often imperfections and some of the flecks lie sideways and some upright. On occasions the flecks are a little distracting but the engraving will be perfect.

Larry Bratton
06-12-2011, 11:08 AM
I've done a few photo/text combo granite tiles that were polished and never masked them. Maybe Bill will check in here, he has a lot of experience with stone and photos.

:) dee

Me too Never masked it ever.