Glass photo engraving

[Pysiek]

I tried to engrave a photo on a glass. When I did that I realized that some small particles of glass are pealing off.
I did some research on internet and find out that I should cool the glass surface by putting a wet newspaper on the top where I will engrave a picture.
I tried that but the paper got burned into the glass and now it looks all crappy.
Is any of you guys have same problem? I did contact Baggy from JQLaser and she told me to increase the speed of engraving and lower the power of laser. I'm not sure if that will help.
Also is it normal that it took 50min. to engrave a small picture of 3" X 4" in size?

[zax15uk]

It sounds like Baggy's suggestions are correct. You will get better results at lower power but also try a lower dpi, which will also speed up the job.

Zax.

[Pysiek]

Which software you guys use for converting the photo? Photoshop or coreldraw? I have seen a tutorial on rabbitlaser.com website in which they use coreldraw and setup the photo to be 400DPI. On JQLaser website they use Photoshop and setup the photo to 1000DPI. Is the software make such a big difference? I don't think if you can see the difference in quality after engraving between 500DPI and 1000DPI. I think you will need to use some kind of magnifying glass to see it.

[twehr]

When engraving glass, you are not vaporizing the material, as you do with wood, paper, etc. You are actually fracturing the glass by exploding air trapped inside. Therefore, the resolution of your image can be (and often should be) quite low - 128 dpi, 256 dpi. I would not go any higher than that.

You will also get better results with poorer quality glass because it has more trapped air and fractures easier.

Glass takes a lot of practice and patience. Once you get it, however, you can get pretty acceptable results. Keep in mind, however, that laser engraving will never be as detailed as sand blasting or etching.

[zax15uk]

The output resolution is different to the photo resolution, although it is a good idea to have them matched.

twehr is absolutely correct, I was going to mention the best results are usually with low quality glass and output of 150-200 dpi.

Zax.

[Pysiek]

Guys when I engraved a picture today it looks terrible again,but what I have noticed is if I put a piece of white paper behind the engraved area it looks like the picture. What is that mean?

[twehr]

Originally Posted by Pysiek Guys when I engraved a picture today it looks terrible again,but what I have noticed is if I put a piece of white paper behind the engraved area it looks like the picture. What is that mean?

It simply means that, because the glass is transparent you cannot see the detail. Putting something behind it allows the detail to be seen.

Try back-painting the glass and see what that looks like.

Glass is not a good medium for multiple levels of gray - works best as a two-tone, either frosted or clear.

[Geoszerda]

Hello Guys!

In these days I made some photo engraving into mirror glass:



This work's gcode was created by DotG software what now released in English:



Check the software here.

[curious]

beautifull.

did you laser it on the backside of the mirror ?
or on glass,with a mirror behind ?

what dpi ?

how dous it look when you look at it not from an angle ?

[Rodney Gold]

That picture does not look good , too much moire patterning.
Search Sawmill Creek Woodworkers Community - The Sawmill Creek Press , in the laser forum for "the gold method" or photograv. Both are the best ways for creating output for a photograph , the gold method is free.
To "dampen" the glass so you do not get uncontrolled fracturing and thus chipping , coat the glass with dishwashing liquid and allow to dry. Easier and better than the wet paper thing.

[Geoszerda]

Originally Posted by curious beautifull. did you laser it on the backside of the mirror ? or on glass,with a mirror behind ? what dpi ? how dous it look when you look at it not from an angle ?

Thank You!
It is made with a diamond tipped tool on the backside of the mirror, every single dot machined separately.
The distance between neighbor pixels is 0,3mm, so the picture size and the raster chosen gives the final size. It looks like a normal mirror, but the worked pixels are white, without reflection. It looks much better in life, the photo made some compression.

[Geoszerda]

Originally Posted by Rodney Gold That picture does not look good , too much moire patterning. Search Sawmill Creek Woodworkers Community - The Sawmill Creek Press , in the laser forum for "the gold method" or photograv. Both are the best ways for creating output for a photograph , the gold method is free. To "dampen" the glass so you do not get uncontrolled fracturing and thus chipping , coat the glass with dishwashing liquid and allow to dry. Easier and better than the wet paper thing.

Thank You, I'll check it.
I had no uncontrolled chipping, I tried to set the tool's pressure to the optimal.


Thanks for the idea with dishwashing, I'll try it out.