View Full Version : Anybody work with glass? Got a question or two...


Lomotil
01-16-2012, 02:06 AM
First, I have a screen-printed collectible glass tumbler that I somehow fractured along the edge, and would prefer not to toss it out. Is there a way that I can trim down 1/4" of the rim and save it? My first thoughts involved using a belt sander, being careful to not heat the glass too much that it shatters...

The other endeavor I've got is with a broken piece of Pyrex. I'm not sure what the initial purpose of this particular design was, but it's essentially a glass tumbler, necked down, then flared out to the original width. This particular piece has been shattered above the necking down portion, and I think it would be easier to work with (borosilicate glass, greater resistance to thermal shock.) I'd still like to save this piece for future use...

Any ideas or suggestions as to how I can re-shape either piece without ruining them?

nehog
01-16-2012, 06:10 AM
Find a glass blower and see what they say. At the university where I teach, we have a glass studio and that's where I'd go for glass advice (actually I'd ask one of my students who knows glass, and is taking glass blowing courses, in fact I'll ask him when I see him on Thursday if you'd like...) The issue is (IMHO, and I know little about glass working) is that the printing may be done with colors that will be damaged by the heat needed to fix the damage. (I don't know, and possibly you'd not be able to find out without trying...)

The Pyrex may be borosilicate and I don't think you can rework it.

Lomotil
01-16-2012, 05:38 PM
I'd be worried about the printing if applying heat to it, it's very close to the area of the tumbler that's chipped. The Pyrex, however, doesn't have any printing on it.

On the printed tumbler, I would be happy with a smooth, satin-like finish on the rim, maybe some sort of grinding, followed with polishing? Maybe some gentle use of a buffer wheel?

I'd be interested in what your student might suggest, too...

kbs2244
01-16-2012, 08:32 PM
It might be time for some experimenting.

The SWMBO wanted some wine bottles made into candle holders.

After cutting off the bottoms,
(BTW, Use a tile cutting saw. I had to make up a bench rest, but still iIt is by far the easiest way to do it.)
I still had some rough edges.
I used my powered wire wheel.
Better, but not good enough.

A propane torch and a steady hand did the job.
You have to hold the edge in the “hot spot” just long enough for it to get soft.
That removes any lip cutting edges.

Be ready to throw away some.
It is not a 100% procedure.
You will break some.
Out of six I cut, we got four she was happy with.

But now we get to drink more wine to get the raw materials to work with.

hickmlg09
01-16-2012, 08:50 PM
Kbutt does. Ask him.

893cv
01-16-2012, 08:51 PM
Yes, you are looking for a glass shop that has a Sumaca wet belt sander. Start with one of the course abrasive belts, then finer belts and end up with a cork belt. Most window glass shops will have a Sumaca, and a big shop will be able to finish the repair with a full polish on a felt wheel with cerium oxide. It is all cold working, so the printing will be safe.

Yes, My MFA is in glass from SIU-Carbondale. This time of year I do miss the heat!

Jon

Lomotil
01-16-2012, 10:12 PM
It might be time for some experimenting.

The SWMBO wanted some wine bottles made into candle holders.

After cutting off the bottoms,
(BTW, Use a tile cutting saw. I had to make up a bench rest, but still iIt is by far the easiest way to do it.)
I still had some rough edges.
I used my powered wire wheel.
Better, but not good enough.

A propane torch and a steady hand did the job.
You have to hold the edge in the “hot spot” just long enough for it to get soft.
That removes any lip cutting edges.

Be ready to throw away some.
It is not a 100% procedure.
You will break some.
Out of six I cut, we got four she was happy with.

But now we get to drink more wine to get the raw materials to work with.

The glass I'm trying to 'save' is quite a bit thinner than a wine bottle, but you've given me an idea for another project... :beer:

Kbutt does. Ask him.

:lol_hitti

Yes, you are looking for a glass shop that has a Sumaca wet belt sander. Start with one of the course abrasive belts, then finer belts and end up with a cork belt. Most window glass shops will have a Sumaca, and a big shop will be able to finish the repair with a full polish on a felt wheel with cerium oxide. It is all cold working, so the printing will be safe.

Yes, My MFA is in glass from SIU-Carbondale. This time of year I do miss the heat!

Jon

:shocking: Just looked up how much those sanders cost - if I took the glass to a shop with one, it'd probably cost me more than the glass is worth. Gave me a great idea, though - I've got some friends in the 'rockhound' group, and there's a couple people in the group that might have some similar equipment...

MoonRise
01-17-2012, 10:16 AM
Glass grinder (usually diamond with water cooling) to smooth off the chipped edge and then a lot of time polishing the ground edge.

Pyrex piece, same idea. Unless you somehow find a glass worker who can also work 'hot' with full-up kiln pre-heat and then work the edge hot, and then anneal in the kiln. Just blasting the broken edge with a flame probably ain't going to work there. Borosilicate glass is resistant to thermal shock, not impervious.

Some "PYREX" and "pyrex" info (apparently they are not the same material any more)

http://en.wikipedia.org/wiki/Pyrex