What is happening to my glass cutting?

[rudgey]

Hello all, I have had a very frustrating day not being able to cut glass.. I normally have no problem.
I normally use artglass now as that what my customers want, however I had one who wanted normal 2mm float to keep the cost down. Could I cut this .. no.. around 700x 500 so not too large but kept going in all directions. After a few sheets I purchased a new oil Toyo cutter thinking my old one was worn, but made no difference and kept skipping the cut in place, not my usual nice line.
I don’t normally even think about it, it just normally works every time.
I even tried warming it up a bit with the fan heater as the workshop was around 14deg c.
The only thing I can think of it’s the stock? stock I have had for about 6 months or so, can this make a difference? Does glass go off..
It would have be cheaper to give the lady artglass at no extra cost as that is cutting fine.
Very confused??

[theframer]

Its not a glass with a coating on one side is it, and you have to score one side of the glass and not the other is it?
As this sounds like it.

[JKX]

I think it’s only tru vue con clear/museum and artglass equivalents that need to be scored on only one side; this is standard glass.

Maybe there’s residue left from condensation or something, try cleaning it before scoring. Clean the glass wheel too, with meths/turps/white spirit.

I have had batches of dodgy glass in the past though, but if this is part of a batch that cut ok last time you used it, it’s probably not that.

[Gesso&Bole]

Probably too cold in the workshop.

[rudgey]

Thanks for the feedback, it’s just normal cheap float glass.
The cutter skipped the line straight out of the box?

New float batch being delivered tomorrow, I will try warming the studio a bit more although normally put in a fan heater to warm up the glass does a trick. I will also try cleaning it if you think that would make a difference.
It’s not exactly dirty but there may be some sort of residue?. It just seems strange that it was skipping in places leaving a blank space which obviously caused no end of issues
With a new cutter, this one is oil based, It really shouldn’t do that.
So maybe the surface not being cleaned can cause it?
I can’t believe temperature would make a difference to the cut only when you snap it off.

So glass does not become brittle with age, 6 to 8 months if left in a cold studio which goes down to 2 degrees at night sometimes.

[fraggle]

Did they deliver the correct glass? If you want to check whether it has a coating just scratch a small area in the corner with a scalpel. You will soon see whether there is a coating on it as you will feel some resistance and it will leave scratch marks.

[rudgey]

I will test, but I don’t think Centrado make that mistake, nice if they would.
I think they only sell Artglass brand and float which you can cut both sides

[Gillthepainter]

I'm an amateur glass cutter, but find it will splinter on me with the tiniest mark on the surface.
Before I cut, I clean the surface to mitigate that with spray glass cleaner. A framer friend told me to use dilute methylated spirit, but I have a huge spray can for my OH's swimming goggles clean up.

In December I had 5 pieces of 2mm glass remaining and 4 had failed. It hadn't even occurred to me that the tiny Sharpie dot I was putting on the glass to align the ruler was causing a path for the glass to break off.
I was scratching my head.
The 5th piece cut as it should, when I stopped that.

As I say, amateur here, but I do now have the confidence to do it.

[rudgey]

Received new stock and it cut ok?? Maybe the studio was warmer but that shouldn’t effect the cut line..
Maybe glass hardened in 7 months..poor quality batch??

[Justintime]

Google says minimum temp for cutting glass is 12oC , so you weren't far above that.
Only issue I've had was when given a load of sheets from a retiring framer. They'd been stored upright against each other without anything between them. They'd marked where they were touching and nothing was going to remove the marks...had to recycle the lot!

[MITREMAN]

My Rules for glass.
Don’t cut cold glass (bring it up to room temperature)
Don’t cut old glass down to size for customers provide a new bit.
Don’t cut dirty glass (50/50 chance of braking)
Using customer’s old glass on refits and mount replacements usually cost you more time cleaning paint and bugs off, then you find a scratch that shows up on your new mount. Just replace the glass.
With glass cutting wear PPE and use a carbide steel oil filled glass cutter if cutting by hand.
Don’t be frightened of glass cutting respect it and don’t press hard with you cutter, a light hairline score is all you need.
Mitreman

[IFGL]

Glass doesn't go off or change its properties over time, but like others have said it doesn't cut well if it is too cold, it does in fact get more difficult to score as it gets colder, (it's to do with absorption of energy because of something about slower atomic wibbly wobbly thingy bobbins or some such nonsense)

Top and bottom of it, glass gets more brittle as it gets colder and more likely to fracture in the wrong direction, clean and above 10 c and you should be good.