I'm working on a display piece for in front of a new hospital addition. My customer is asking me about sandblasting the medical caduceus (logo) on a piece of glass. The glass will be 6 X 10 feet.
Is tempered glass the way to go? Will regular sandblast stencil, like you use on HDU work on glass? What kind of pitfalls could I run into, aside from the obvious (breakage, etc), and is there a better glass to use?
Or....would an acid etch be easier/better?
Thanks for the input.
[ May 06, 2009, 11:48 AM: Message edited by: Dale Feicke ]
Posted by Barb Schilling (Member # 13) on :
The Etch look vinyls are SO-O-O realistic now that I recently had to feel an etch to determine if it was etched or vinyl. That is how I would go with it.
Posted by jimmy chatham (Member # 525) on :
don't try sandblasting tempered glass it will shatter. ask me how i know.
Posted by Dave Sherby (Member # 698) on :
You can etch tempered glass but that's it. (Etch as in a light frosted look) Sandblasting (sand carving)to any depth at all will usually end up in the glass breaking. And not necessarily right away. Tempered glass is strong, but the tempering process puts a lot of tension on the glass surface. If you change that tension by going anything beyond a light frost (etch) the glass has a very good chance of breaking.
Building codes usually call for tempered glass in public places so I would take Barb's suggestion and show him etched vinyl on the glass and see if he'll go for it. After all, the look will be the same and the vinyl will be much safer.
Posted by Dale Feicke (Member # 767) on :
I really don't want to use vinyl, unless as a last resort. I don't have all the details yet, but I want to have some educated answers beforehand to upcoming questions.
This will be more of a sculpture than a sign, incorporating a huge block of limestone,this glass piece and some wrought iron.
I may not even want to do this, but am always looking for different stuff to do. Would plate glass work better, or.....? Even, what about plexiglass???
Posted by Tony Vickio (Member # 2265) on :
Hi Dale, I have blasted Tempered glass many times. You have to be very careful, as Jimmy mentioned. I just frost the surface using a lower pressure as to not create any more heat than you have to. The blasting process causes heat and that will stress the glass and break it. As long as you are simply frosting the surface I would mask it and lightly blast it. I would explain to the customer about the tempered glass and I would have, in writing, a paper stating that it is tempered glass and that you are not responsible for breakage. Plate glass probably will not meet code and plexiglass will not have the crisp look of glass.
Posted by John Arnott (Member # 215) on :
You can also blast plate glass, then have it tempered. You can "Frost" tempered glass.
Posted by Brian Oliver (Member # 2019) on :
I have blasted glass many, many times. I always used plate. As for the breakage problem, you could perhaps frame it with steel channel or something.
John, I was always told that tempering plate glass after blasting was very risky. Breakage probability is high, and then you've lost the material and your time.
By the way, if you want to get a very appealing depth, use 1/4" glass. Trouble is, it's very heavy. You might want to do it in in place, on-site.
Good luck.
[ May 06, 2009, 01:31 PM: Message edited by: Brian Oliver ]
Posted by vance galliher (Member # 581) on :
Dale, sandblasting and stage carved glass is the bulk of my work. I use both annealed and tempered glass. In fact at this moment I'm taking a break (oops, shouldn't use that word) from doing a two toned etch (blasting with different grits of silica and green diamond) on several large panels of 3/8" tempered glass. I know it's risky work with tempered, but the architects had already ordered the panels for the client. I charge alot for that risk factor with tempered glass, but I've never had a problem. Pressure pot should be no higher than 60#. I just finished a project on two large plex panels and it looks really good. I'm not a vinyl person and I don't like the look or feel of it. A 6'x10' panel is hard to handle, but doable. For all my glass work, I use Hartco 310S masking.....have fun !
Posted by Raymond Chapman (Member # 361) on :
Mike is blasting some tempered glass as I type this. You just have to be very careful and frost the glass only...not much depth.
When the glass breaks there is no warning. One second you are just happily doing your thing and the next second you have about two million little pieces.
Keep the nozzle moving because heat will build up quickly if you stay in one place too long.
You can blast regular glass and then have it tempered but you will get no guarantee that it won't break in the tempering process. You just take your chances.
We use Gerber Mask 2 for the stencil, but just about any mask will work for light frosing, even cheap vinyl
Posted by Ray Rheaume (Member # 3794) on :
I don't do glass blasting, but one of the trends in the auto restoration shops is soda blasting. The heat doesn't build as quickly and it leaves a very smooth finish behind. Some shops go straight to the primer, skipping any additional sanding. Yeah, it's that smooth. Don't know if it would work for glass, but I figured I'd throw the thought up and see if anyone who has tried it could share the experience.
Rapid
Posted by Joe Crumley (Member # 2307) on :
Would un-tempered glass meet OSHA hospital regulations?
Posted by Steve Carter (Member # 494) on :
By my business name, I only etch glass! (30+ years)
Two years ago, I etched 120 1/2" tempered glass panels for a local casino in an unheated building in the winter having to bring the heat up each day to apply stencils and then blast the designs.
I have to agree with many of the responses here. Do a light blasting, move the blasting so as not to build up any heat. I do not recommend stage blasting due to the stress applied to the tempered glass. Take your time and wear an air supplied mask!
By the way - 120 panels & no breakage!
Posted by Dale Feicke (Member # 767) on :
Thanks very much for all the responses. I know this type of work is 'risky business' and would like to avoid as many pitfalls as possible. I have a knack for finding pitfalls of my own.
I have a meeting set up with them for next week, and am hoping to have some answers from them, and for them.
[ May 07, 2009, 01:25 PM: Message edited by: Dale Feicke ]
Posted by John Byrd (Member # 825) on :
I would also look into 'safety glass'. It's like the windshield on your car. Pretty much two plate glass panels glued together with a membrane down the middle. I have ordered it custom thicknesses for jobs like yours. 1/4" on 1/8" etc.
