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View Full Version : Anybody know how to stamp on glass surface?


tip
03-21-2004, 12:21 PM
Hello, guys, with the helps from a lot of nice folks here, I am finally able to post a new thread here! Thank you all!
So here is my question:
I plan to use a metal piece to stamp a pattern onto the surface of a finished glassware. It's basicly a question on how to indent grooves onto a glassware. Do I have to melt the whole glassware to do the stamping or I only have to heat up the surface where I want to make the pattern? And if the pattern is shallow so it doesn't deform the glass a lot, do I have to anneal the whole glassware afterwards? Also is it possible to heat the metal piece really hot and stamp while the glassware is cold?
I came up with this question, 'cause I noticed they have those small trademarks on the bottom of regular glass cups, which appear to be made by stamping. I don't think it is from the original molds, 'cause the position of the marks are usually different from one cup to another.
I asked this question to many people in this forum before and got a lot of valueable suggestions! And I will really appreciate it if you can share some of your experience on this!

Regards,
Tip

!ngridh
03-21-2004, 12:29 PM
The glass is hot and soft and can be pressed to a raised surface and an indentation of the image is there...for the reverse...the hot soft glass will be pressed against a surface that is hollowed out of the form and the glass fills the image. That is very simplistic but more or less the process..

davebross
03-21-2004, 12:49 PM
The glass will have to be hot enough that it doesn't thermal shock from being touched by the colder stamp. The high end of the annealing range or higher would do it. This would be somewhere around 1000F and up for most soda lime glass.

If you don't want chill marks with the stamp marks, the stamp will have to be hot. If it's too hot it will stick to the glass.

Right where you will stamp it, the glass has to be hot enough to be soft enough to take the impression.

Example: The old West Virginia paperweight makers used to stamp the bottoms of the weights. The paperweight would be cracked off the pontil into some sand or other soft refractory. It had to be hot, so that the cooler stamp wouldn't crack it from thermal shock, but not so hot that the sand would make impressions on the surface. The bottom would be heated up until soft with a torch, stamped with the stamp (the stamp was usually hot from doing a number of them in rapid succession) and then the paperweight would be put away in the annealer.

ValorieCox
03-21-2004, 10:20 PM
Bobby Pederson was making some nice glass stamps out of very thin brass strips. (they were about 1/4" strips, several inches long, and very thin). She formed the brass into a couple letterforms, added a handle on the back side, and pressed very deeply into a hot spot on the glass. A small indentation--it looked good!

Val

Plato
03-22-2004, 12:49 AM
Tip

Reheating finished glassware can be very tricky,especially if it`s molded or machine made(look for the seam ;) )Unless you know what you`re doing,you`ll probably end up with hot (and sharp) pieces of glass flying around.

A word to the wise.... ;)

Plato :)

Zinguvok
03-22-2004, 03:05 PM
Don't know exactly what purpose this is for, but would it work for you to sandblast the lettering or whatnot instead? You could easily make a resist template if you're doing small production or something... and sandblasting can make some pretty deep grooves in glass without difficulty. Just a thought.

tip
03-22-2004, 08:25 PM
Thanks to all your nice suggestions! :) I am actually trying to make some glass seals from pre-made glass rods (or glass art piece) by stamping patterns on bottoms of them. Since I don't have torch, I hope I can build a small tube furnace which can just hold the glass rod and only heat the bottom of it. I tried today with some window glass scrap and my stainless steal stamp, it works pretty fine, at least the glass didn't crack after the patterns were stamped on it!
Sandblasting, sounds like a good idea! Zinguvok, do you have links to this product? Thanks!

Zinguvok
03-23-2004, 03:46 PM
I'd say that if your current method is working, don't bother with sandblasting... it produces a "frosted" surface which may not be what you want, and would probably take about $300 worth of equipment to get you started, assuming you don't have a sandblasting setup already.