Engraving on Glass: A Curious Thing

[Chris DeGerolamo]

I've engraved plenty of glasses and inevitably a letter or two doesn't seem to show as 'frosted' from time to time. I had a project this morning where that was the case: letters within a name did not show evenly, but of course there's nothing you can do about it, right?

I know how the laser reacts to glass (heating - cooling - microfracture etc) but a new thing I found today while pointing out the lighter letters was that you can force them to "break".

**By tapping the letters with my nail, I could "complete the stress" on the glass and cause the engraving to instantly POP (yes with audible sound).**

Of course I sat there like a kid with bubble wrap and popped all of the remaining characters. I'd really like to hear if you guys/gals have success with this.

[Dan Hintz]

Increase your power a little bit...

[Joe Hillmann]

I have found that works on some high end champagne flutes I did, the weren't "normal" glass though.

[Chuck Stone]

I've found that freezing the glass and then running water over it can
cause the missing letters to show up. OR sometimes they just show
up a few hours later for no apparent reason. (apparent to me!)
But the freezing method doesn't work well for volume

[Mark Sipes]

Since I went to the 70% black fill instead or 100 I get a much better frosted appearance and less of the chipped look.....

[Chuck Stone]

Since I went to the 70% black fill instead or 100 I get a much better frosted appearance and less of the chipped look.....

I'm curious, as I've seen this before and don't really understand it. If you lower the % of
black fill, don't you need to compensate by increasing the power? Or am I mis-understanding
the %? (very possible) It is changing the color within the file, or it is changing the
spacing of the black dots within the file? If it means changing the color and then upping
the power or slowing down the speed, I'm not seeing how it would be better.

note: I usually work from grayscale images out of Photoshop so I'm not
all that clued in on how the bitmaps work in Corel.

[Zlatko Kursar]

Yesterday I made 13 glass plaque and I have same problem. My black fill is 80%. Then I tried it with less power (from 100% to 50%) and works very fine.

[lee chitwood]

You can "dress" the engraving area with a small piece of acrylic by rubbing a corner of the edge directly on the engraving. This technique knocks off the small chips as well as smoothing the edges. My fear was a customer getting the micro slivers in their fingers as well as my own.

[Martin Boekers]

I haven't been able to resolve this issue, I have run at different speeds, powers, frequencies etc even multiple passes at times.
It gets frustrating. I have used burnishing tools with limited success. Next time I'll give these ideas a try. I have seen some here
have amazing success with glass, so far I haven't been able to get the consitancy down.

[Dan Hintz]

I'm curious, as I've seen this before and don't really understand it. If you lower the % of
black fill, don't you need to compensate by increasing the power? Or am I mis-understanding
the %? (very possible) It is changing the color within the file, or it is changing the
spacing of the black dots within the file? If it means changing the color and then upping
the power or slowing down the speed, I'm not seeing how it would be better.

Chuck,

By lowering the black level to something less than 100%, you're allowing the driver to dither the pattern of dots rather than blast away at every single location. This provides a more realistic sand-blasted effect.

[Chuck Stone]

Chuck,

By lowering the black level to something less than 100%, you're allowing the driver to dither the pattern of dots rather than blast away at every single location. This provides a more realistic sand-blasted effect.

Ok .. now I understand. This would be when sending a solid color to the engraver,
rather than an image that has already been dithered by the bitmap conversion.
(otherwise you'd be double dithering)

[Dan Hintz]

Correct.....