What you are about to read will make a big difference in your stained glass cutting skills. There’s nothing earth shattering, just plain common sense. However, cutting stained glass and common sense don’t always go hand in hand, especially if you’re new to stained glass work. The instructions, that follow, are applicable to window glass and mirror glass also. You can also use this info to cut glass bottles if you are making candles, but that’s for another site on another day!
You will hear some people call it scoring the glass, others will say cutting the glass. Score and cut are synonymous with each other. Scoring is more accurate really because you are not actually cutting the glass.
A glass cutter isn’t even really sharp, run a glass cutter over your hand. It won’t cut you.
Glass is a solid liquid. In other words, it’s molecular structure does not change from the liquid form to the solid form. When we run a glass cutter over a piece of glass, we make a scratch that disturbs the surface tension and the glass will break along that disturbed line. In that light, that’s why scoring glass is a more appropriate description, but a lot of people call it “cutting glass”.
Please remember to wear eye protection when cutting stained glass, or any glass for that matter. I can tell you, from experience, that getting a piece of glass in your eye is not fun! No matter how careful you are, without eye protection it can happen. You need goggles that fit close to your face. NO READING GLASSES
One other thing to remember, before you start cutting stained glass, make sure the glass is clean. Wash it with warm, soapy water if it is very dirty. Otherwise, a squirt of Windex and a paper towel will work. Dirty glass will dull your cutting wheel very quickly.
1. If you are able, stand up to cut glass. The movement of your body and your shoulder will give you better control over the cutter. Don’t stand so close to the cutting table that you don’t have room to move. Stand with your legs slightly apart so that you have good balance and are able to move your body as you are cutting the glass.
2. You can push or pull your glass cutter – it doesn’t matter which way you do it. You may find some cuts easier to do one way and some the other. Get comfortable cutting glass in one direction first. When that way is second nature to you, learn how to cut it in the other direction.
3. Find a way that is comfortable for you to hold your glass cutter. There are no rules for holding a cutter when you are cutting glass, there are only rules on how the cutter must set on the glass. The rules are:
(a)The cutter wheel must be absolutely perpendicular to the glass, it can not lean to the left or right, this includes going around curves; remember – only motorcycles lean into curves.
(b)You must be able to see the cutter wheel and the line you are cutting along, at all times.
4. Always maintain the same pressure, right to the very edge of the glass. If you let up on the pressure before the end of the cut, the glass will be difficult to break. You want to hear a static or zipper sound from beginning to end. Pressing too hard will only gouge the glass and cause problems such as: not breaking along the score line, damaging the cutter wheel, and giving you a sore hand and shoulder. It takes practice to learn just how hard to press on your cutter.
5. Start cutting glass 1/16th inch from the edge, and continue cutting, slow and steady, until you roll over the other edge, trying not to jam the cutter into the table.
6. Always break the glass/run the score from the edge that you finished cutting on.
7. If you use pattern pieces and trace around them with a marking pen, always cut on the inside of the line. If you cut on the outside of the line, your cut piece of glass will grow in size and be too big for the pattern.
8. Always use a working piece when cutting glass for your project. Don’t try to cut from the full sheet. If something goes wrong you’ll end up ruining the full sheet of glass. A smaller piece is easier to handle and there isn’t so much wastage.
9. If you have an odd shape to cut, always cut from the narrowest end to the widest end.
10. Do the most difficult cut first. If it is a deep inside curve, you need the mass of glass around it to prevent it from fracturing.
11. Take out deep curves in a series of small cuts rather than one big one. This will prevent you from losing the corners or breaking the piece.
You can learn more about the techniques by watching this video
12. Cut slow and steady. SPEED DOESN’T COUNT!! Maintaining even pressure is the most important thing to remember.
13. You can stop cutting the glass in the middle of a score if you need to regain your thoughts. Just remember not to lift the cutter off of the glass and do maintain the pressure until you are ready to continue. And, remember that you must always finish the score from one edge of the glass to the other. Never abandon a score line, even if it’s wrong.
14. NEVER GO OVER A SCORE THE SECOND TIME. This will ruin your cutter. If you have gone off the line or made a mistake, cut to the other edge of the glass, break it off and start again.
15. Never leave a piece of glass sticking out over the edge of the table. The only bad injuries that I’ve seen have been from glass left in this manner.
16. Make sure you are cutting the glass on the smoothest side.
17. When you are cutting glass, use a small brush to keep glass chips and splinters cleaned off of the work area. Your glass can get scratched and you can get cuts from them.
18. If you are having trouble cutting a particular shape out of colored glass, use a piece of window glass for practice and try to figure out what the problem is. Maybe you are not doing the most difficult cut first (see #10); or maybe you are trying to take out too big of a piece (cut it out little by little); maybe you have an impossible or very difficult cut that needs to be modified; or you might be trying to cut on the wrong side of the glass. You can learn more about impossible cuts here
19. Keep your body relaxed and in a position where you can maneuver your arm and hand when you are cutting glass. Always stand directly in front of the glass, and MAKE SURE YOU CAN SEE THE WHEEL AND THE LINE YOU ARE CUTTING ALONG. Make sure you are comfortable. Your table height should be somewhere between your hips and your waist. Work at a height that doesn’t make your shoulders tired.
20. Cutting the glass on a stack of 10-12 sheets of newspaper will give you a soft surface to cut on. The glass chips and splinters can then be wrapped up in a sheet of paper, leaving a clean work surface underneath.