I have found that contrary to all advice here the only way to get most glass to engrave is to use about 4 times the power that shows a good mark.

I always get some edge fracturing, really small but not up to my quality levels. It also left fragments that you could not see but would stick in your fingers. I did a test of the higher power after trying every piece of advice. It gave me a nearly sandblasted result with no fracturing. When I say nearly sandblasted result I mean that glass was removed and a blasted look was achieved.

Philadelphia, PA (Really Bensalem)

Harvey's Tips Page When you finally understand it completely... it changes.

When you bump up the power, do you still use a wet paper towel? Can you share a power setting, speed and wattage? I will try it to see if I get a quality comparable to blasting.

Thanks!

I don't think you can get a quality comparable to sand carving. At first I was very happy with just the laser on glass (and still am for photos), but after getting a small blast cabnet, I don't offer straight lasering any more. I always follow up with the sand blaster. There is just no comparison to me.
Bob

Harvey,
I use 100p 40s 300ppi 3ID and process the photo in PhotoGrav. The picture here is really a bad representation of what it looks like in person, but gets the point across I think. I do photos on glass fairly often, but I always sand carve everything else.
Bob

If that is a bad representation, I'd fall off my chair seeing a good one.

Your power settings are close to mine. Very interesting.

I am not sure what 3ID is, is it a diameter?

Apparently 300 PPI, (reduces the DPI to at least as low as 300), is a good value for glass.

Philadelphia, PA (Really Bensalem)

Harvey's Tips Page When you finally understand it completely... it changes.

To reiterate, I now laser at 1000 dpi. 100% power through signwriters application tape on glasses, then sandblast lightly using the application tape as a mask. All with a 25watt GCC Mercury.
It's the only way I can achieve consistent results on glass with the laser as I find that glass varies so much.
Also easier than photo-resist. The application tape seems to conform to compound curves reasonably well, and the resulting work tends to be consistently straighter round the glass than photo resist or vinyl.

Harvey,
ID is image density (same as DPI) (I have a ULS M-360, 40w). Glass seems to work best at a setting of 3 with the PPI set at 300. Like I said, I can laser photos with this, but the lettering and other non-photos I very much prefer blasting.
Bob

Ken,
I do spray paint bottles, and sometimes will hand paint small flowers or other things. It can be a pain, but I've recently found that Krylon Fusion paint seems to do real well.
Bob

I'm sorry all of you laser people, there is no comparison between laser engraving glass and sandblasting. Laser on glass shatters the edges and besides you can't get any depth to the cut. Photo resist is the best way and when all is compared, it is the least expensive.
I do an awful lot of crystal and glass, the cost of photo resist is approximately $0.06 per square inch. On an average toasting glass that means you might be looking at $0.50. All other costs are labor which you would have in setting up your machine so they are a wash. I charge $20-30.00 a pair for blasting crystal toasting glasses which total actual time takes 15 minutes start to finish.
Yes there is some learning curve but that is in anything we do in this industry. As far as the curves on the glass the orange is a way but here is another that I use on a lot of pieces. By the way I only do this for pieces that I will always be doing again.
1-Take masking tape and put it across the area that you want to engrave.
2- Turn the glass upside down so that you are using the straight edge of the top of the glass for your alignment.
3- Draw as many lines as you need for what you are going to engrave on the glass making them parallel with the top of the glass. I use a vertical height gauge modified to hold a wet erase marker.
4- Make sure you mark the center of all of the lines.
5- Peel of the masking tape from the glass and apply it to a flat piece of paper. You might have to make cuts in this to make it lay flat, just as you would to put a mask on the glass itself.
6- Take this and scan it into whatever graphics program you are using (I use Corel) and trace the lines so that you have a vector setup for your glass.
7- Now save the vector lines as a blank template for the glass or vase so that you can always import it in the future.
8- Type your text and select the lines you want it on and fit text to path. The mask will look crazy, put it will make your lines exactly straight and easier to put on the curved surface.

Sorry for the length of this just got carried away. Hope it might help

Way too much work for me!
All glasses are not the same, so you would have to have a number of different templates. Same goes for inscriptions with different numbers of lines of text.
I guess you could do it that quickly if you have dedicated workshop areas for exposing, washing out, etc., but I don't, so can't come near to your time of 15 minutes.
Enjoyed your great informative post though. Thanks!!

Hi Bill,

Thank you for sharing. I use this technique on one-of-a-kind larger pieces as well, primarilly because I want it to look it's best and am able to charge for the extra time it takes.