Etching Safety Glass

[Scott Shepherd]

I have a request to etch some safety glass and was wondering if there's anything special I need to know/do because it's safety glass.

I ran some samples on normal glass to give him something to look at, quality wise. What a pain. Can't get a good consistant image. Tried the wet paper on it, 1/2 way through the paper is dry from air circulation. If you pause it and spray it again and start it again, you'll see where it was restarted. Very slightly, but you can still see it, which is no good.

Tried without the wet paper, no good. Low power, high power, and everywhere in between. I finally went to 50% black on the image and it dithered (?) a fairly good image, but only at 600DPI, which isn't quite as sharp as he'll want it to be. 1200 DPI with 50% black gives me the paper drying issue.

I remember there being a mask that you burn through that people said worked quite well. It was made for burning onto glass, but I can't seem to find where or what it was.

So, can I do the safety glass no problems? Same settings as normal glass? That's my today issue, my long term tomorrow issues are finding the masking material.

Thanks in advance!

[Stephen Beckham]

Scott,

You'll find pros and cons for the wetting or not from both sides of the aisle.

My understanding of safety glass is that it's two pieces sandwiched around a polymer or plastic that keeps it from shattering when cracked. The tendency for it then is to crack and run versus breaking.

Question - will the saftey glass be put in stable environment or outside? If outside, you'll have the extreme heat and cool situation that could cause the stress fractures.

Also - I'd get a very high powered magnifying glass or a jeweler's monical (laserbits carries them) for getting a good view. Make sure whether you have tiny cracks outside the divits or if you have clean divits when etching.

Only other comment would be to request a sample of the safety glass to confirm the etching on. You should be able to get a small piece to make sure nothing unexpected will happen.

[Joe Pelonio]

I seem to remember someone saying that any kind of etching of safety glass is likely to weaken it, which can cause it to shatter. An alternative is to apply "etched" or "frosted" cut vinyl to it. Won't work with really tiny detail though.

[Belinda Barfield]

I was told by someone who tempers glass that laser etching/engraving will weaken the exterior glass, with resultant cracking, etc., when exposed to heat (much like that little windshield chip will run all the way across the windshield). This might make it easier to shatter, and will probably void any warranty. Don't take my word for it though as I haven't researched beyond that.

[Mike Null]

The info I'm copying is from an industrial newsletter. Virtek is a laser mfr.


Spec-Temp (Antwerp, OH), a glass fabricating and tempering company serves the automotive and marine industries, as well as commercial and home fixturing manufacturers. Their capabilities include glass bending, screen-printing, edgework, custom holes, tempering, and heat strengthening.

With its existing sand etching systems the company was required to mark before the washer, which meant that it did not have the flexibility to respond to varying production demands. The sand etching process was also labor-intensive, prone to operator error and poor mark quality. Plus, the need for cost-effective date coding was another factor that spurred the company to seek alternate marking technology.

They installed three Virtek GlasMark Mobile systems that are easily moved around the shop floor to mark tempering logos and date codes on the different glass products. Production demands are now easily met with the mobile units providing maximum efficiency and flexibility. GlasMark software allows the work to be programmed from Spec-Temp's internal main computer network so customized marking is fast and easy.

According to Ray DeLong, product manager, "The three systems paid for themselves in less than six months based on reduced scrap and labor savings from reduced re-work alone."

The GlasMark systems provide a higher quality mark and more consistent results than sand-etching, which is subject to wear and tear of masks and reliant on operator efficiency. Spec-Temp has successfully converted this into increased sales by offering custom marking of logos. Customers readily appreciate this value-added service as it increases their visibility in the marketplace

[Mike Null]

Scott

I don't mark a lot of glass but I find better results using 300 dpi and two passes.

Joe

Beautiful work and a great example.

[Nancy Laird]

I had a friend give me a hint about lasering glass- put a wash of dishwashing liquid on the glass - maybe cut to about 25% with water. Keeps the chipping down and the image turns out a lot better. I haven't tried it--but that time is coming soon. I'll post results.

Nancy (134 days)

[Scott Shepherd]

Thanks all- I should have stated, the safety glass will be indoors, actually in a piece of furniture, such as a cabinet with little use at all. I've already suggested frosted vinyl and he doesn't want it.

[Craig Hogarth]

Can't get a good consistant image. Tried the wet paper on it, 1/2 way through the paper is dry from air circulation. If you pause it and spray it again and start it again, you'll see where it was restarted. Very slightly, but you can still see it, which is no good. 50% black gives me the paper drying issue.


I'm still a laser newbie. so I don't know if this sound advice, but when doing glass, I use a wet paper towel and keep the exhaust off. The towel won't dry at all, even on lasered areas.

I figure since there's really no material being removed, the exhaust isn't necessary.

[Belinda Barfield]

Thanks Mike. I remember from our thread the other day that you mentioned laser marking was being done on safety glass with no problems. I appreciate you posting documentation on this.

[Dave Fifield]

I was lead to believe that if you tamper with safety glass in any way at all (e.g. engraving it), you can become liable for any damage or injuries caused by its subsequent failure thereafter.

Since this piece of glass is going into furniture, if I were you, I'd pass on this job and advise the customer NOT to have the engraving done at all, or do the engraving prior to the tempering process.

Cheers,

[Larry Bratton]

Scott:
I have done a good bit of glass. Most of it the graphics have been processed with Photograv and rastered at 300dpi. I don't know if you have Photograv or not, if you don't send me the image and I might could process it for you. Anyway, if you do, be sure and make the background black in the graphic your sending to Photograv. Otherwise the graphic will have a white box etched around it. (Photograv reverses black to white in the process and the laser does not see a pixel, subsequently does not fire and leaves that area clear).
I assume by "safety" glass you mean tempered? I have not tried any tempered. Tempered has been heat treated to give it that property. I would not see a problem with lasering it, but check other sources.
One thing to watch out for in doing glass is the dust that comes off it. It will cloud your focus lense pronto. The wet newspaper trick may work for that purpose. I did that on some glass I did and couldn't tell any difference in the engraving, but if it held the dust down, that would serve a useful purpose. I didn't think about it at the time.
Come to think of it, I have sandblasted tempered glass in doors without a problem but no laser work.

[Scott Shepherd]

Thanks for the input everyone. The customer just brought it in and I saw it's purpose. No safety issue that I can see. Stuff is about 3/8" thick with the plastic center, and it's going in a very small place. Any glass that small, that thick, would have to have something really bad happen before anyone gets hurt from it breaking.

Larry, I don't have Photograve, but I think I've got this one image tuned fairly well. I appreciate the offer to help with it. We have been unable to do photos due to the problems we have had with the laser, but hopefully that's all going to change in short period of time, and then we can get into some photographs.

[Stephen Beckham]

I like using the images at 300 DPI, but actually lasering at 600 DPI. Takes longer, but gives a better frosting in the solid black areas of the image.

Good luck with the job.

[Scott Shepherd]

Just finished up the job, I think it went fairly well. Glass seemed a lot more consistant than the sample normal glass I ran was. Gave a nice, even pattern over the entire image.

Just thought I would report back for any future readers of the post.

I didn't see any issues. Ran at 35S/85P on 45W machine.

[Tom Bull]

There are 2 forms of safety glass: laminated and tempered. The laminated is like a windshield, it has two layers of annealed (regular, cutable) glass with a polymer layer between. When broken it remains glued together and no large pieces come off to seriously cut. The tempered glass is regular annealed glass that has been heated to a specific temperature and then rapidly cooled in a controlled environment. When it breaks it shatters into very small pieces that can cause "glass rash" (been there, done that) but no serious damage. It is like the side window in your car.
We do a lot of sandblast etching on glass at my workplace. The safety of the tempered glass is not compromised by the etching, but there is some question as to whether it is weakened. We have carved as much as 25% of the thickness away and the piece is still good after 7 years. It is on an interior door and used a lot.
Another option is to do the art and then have the piece tempered after. Most tempering facilities are at your own risk, so....
Hope this is of some help, you have all been a great help to me,
Tom

[Bill Cunningham]

I have a nice piece of 'smoke' tempered glass.. Not knowing much about it, it's pretty well done nothing but sit for a few years.. Can you cut this stuff with a glass cutter? Or will it shatter?