how do i susesfully cut 20+ year old glass when i try it shatters?

Question

and yes i used a glass cutter to score it but when i go to "seperate" it it brakes!
its aprx 1/4
and has been out doors for 20+ years.

Answer 1

Age absolutely does matter when cutting glass! Old glass that has been stored in a controlled temperature environment is not a problem, but heating and cooling cycles cause the crystal structures within the glass to change, making the glass brittle and darn near impossible to cut. The aged glass is actually slightly stronger to impacts.

I worked at a hardware store in my (much) younger days and we sold glass. Standing rule was that we would attempt to cut glass that customers brought in with a warning that it probably would not work.

The heating and cooling cycles mimic the process of tempering glass, just on a much smaller scale. Tempered glass is impossible to cut using the traditional scoring method, it must be cut by an abrasive saw.

I had thoughts that this might be tempered glass, but tempered glass will shatter as soon as you put the glass cutter to it, not when you try to break it on the score.

Answer 2

Age should not matter. What does matter is if the glass is tempered or not. Tempered glass WILL shatter if cut with a glass cutter. Glass cutters are meant to be used with Anealled glass - glass that was not heated (or tempered for safety). Glass cutters are really scoring the surface of the glass to weaken it, then the glass is snapped at the line of the score.

If the glass is breaking when using the glass cutter - more than likely, the glass is tempered - which cannot be "cut" by any means available to the consumer. Tempered glass is cut to the size needed first then TEMPERED by heat then sold to the consumer.

Answer 3

Tempered glass is very hard to cut, I can't, it will shatter, I mistakenly found this out by buying a bunch of former sliding glass panels thinking i was wise to do this, but. I found out why the guy was selling them to late, he couldn't do anything with them, it was tempered glass and couldn't be cut without shattering.
I did get rid of them down the line for inside windows, office separators.

Or, try an oil cutter, their a little spendy but worth it, you'll use it down the line in time to come.

Make sure your glass is on a hard surface, it goes without saying, make sure it's clean, make one clean cut, if not, the oil cutter, then a new glass cutter. Put something like a flat yard stick under the cut and press on the edge evenly of the cut piece and, snap it off. If it still shatters, have someone like a window company do it for you.

Answer 4

I think the problem is not the glass but your technique.

Try getting some regular new window glass and making clean cuts. Use a sharp new cutter, dip it in kerosene, score cleanly in one cut, tap the back of the cut with the back of the cutter, and break over an edge.

Then go back to the real glass you want to cut.

Scientists who tested very old glass did not find any differences in cutting due to its age.

Answer 5

Apparently, you should not apply heavy pressure when you score the glass. You should not really hear anything while scoring - this tells you that you are doing it correctly. If you do hear a sound of cutting you are applying too much pressure and this cut is ruined already - it will not break the way you want it to so move on and try again.
You should make one continuous line in only one direction from begining to end. If you go over it many times you have ruined the score and it will not break as intended - move on and try again.
Here is some good advice on technique:


http://www.wikihow.com/Cut-Glass
http://www.ehow.com/how_1313_cut-glass.html
http://www.associatedcontent.com/article/114933/how_to_cut_glass.html

Answer 6

If your having troubles, take it to any hardware store and let them do it for you, I've cut New glass the same way with positive results. 20+ glass is normally beveled and might need something special. Good luck