Cutting Circles in Stained Glass

Have you ever seen in the movies a cat burglar cut a circle in the window and pull it out with a suction cup? Us glass artists know that it’s impossible. But how do you go about doing it?

I use the Glastar Strip/Circle Cutter but there are many out there that are just as good. The circle cutter setup may be different but the cutting technique is the same.

1. Make sure your piece of glass is at least 1 inch larger than the circle you need.
2. Place circle cutter in center of piece of glass.
3. Do a test run around the circle to make sure you are comfortable pressing down all the way around the circle but do not press down on the cutter. Also make sure the cutter stays on the glass.
4. Press down on the circle cutter and score the glass in circle making sure to have the start and stop points of your score line match up. (Don’t let the center point of the circle cutter move)
5. Break your score line all the way around the circle by using the Morton M80, Morton Safety Break, or flip your glass over with score side down on short pile carpet or rubber pad and press on score line to run the break all the way around.
6. Make 4 relief cuts from your broken score line of the circle to the edge of the glass.
7. Break relief cuts and circle should come out in one piece.

Circles from 4” to 20” will typically break out clean with this technique. Smaller circles than this will usually have flares that will need to be ground. Larger circles are just harder to handle by yourself.

What kind of lightbox do you need for stained glass cutting?

There are many different lightboxes out there to choose from. There’s even a tablet available that will light up in different shades. You don’t need anything fancy just functional. In fact, the hardier and bulkier the better because that way you don’t freak out if you scratch it. It’s meant to be worked on. And you might even progress to the point where you will cut straight on top of the light box and not just use it for tracing the lines.

You will need a box that you can press down on. Wood and clear glass work the best.

If you have a box with plexiglass change it out for real glass, preferably ¼” thick and clear. The reason is because plexi flexes when you press on it. When you score glass you don’t want any bowing when you press down and glass won’t do that. If you were to use plexi it can cause uneven scoring and even cause your glass to break prematurely.

You can easily get a sheet of glass at your local window glass store. They will even cut it to your specifications and polish the edges for you.

The reason you want the glass to be clear is because your pattern paper will be your diffuser. Brightness is your friend when you want to see through the pattern and the glass. Some dense glass will be hard to see through if you don’t have intense enough light. Florescent lights are fine but if you have a choice I would get LED strip lights (as intense as possible) because then it won’t be so hot to work over.

What size lightbox do you need?

Well, I’m very spoiled, I have a very large 5’ x 7’ light table for any and all size panels I might build. But you really don’t need it. Simply have a small lightbox, slightly bigger than your biggest pattern piece around 12” x 12”.

When you use your lightbox have two full sized patterns, one for your lightbox and have the second pattern on a worktable nearby. As you cut out a stained glass piece put it on your worktable pattern. That way your cut pieces are out of the way and you can see your pieces fill your pattern. This will allow you to nearly eliminate piece numbering which can speed up your process as well.

What if I don’t have a lightbox?

You can make a lightbox out of anything that will hold glass above a light. Have an old glass top table? No, go down to your local recycle store and find one. All you need is the glass top table and a portable shop light, a table lamp (with shade removed), or even a strong flashlight under the glass. Be creative: coffee table, end table, dining room table, table with removable tiles (replace with glass).

How do I transfer my stained glass patterns to the glass?

There are many ways to transfer stained glass pattern to your glass, pattern shears, tracing paper etc. I don’t cut out my stained glass patterns at all.

A lightbox is, in my opinion, the most efficient method for stained glass cutting. You can trace your pattern pieces directly on the glass. This will save you loads of time by not cutting out and numbering your pattern pieces. Plus you can get a look at the direction and variations of the glass before you cut it. The only time you will have to cutout a pattern piece will be for extremely dense glass like black (or you can use tracing paper). This is how I use a lightbox:

• Put your pattern on the top of the lit lightbox.
• Put your glass on top of the pattern and position the glass with the variations (streaks, texture, color density…) where you like it to be.
• Trace the pattern on the glass that you want to cut out. (if you are having a hard time seeing the pattern, lift up the glass and trace the pattern line with a sharpie to make it darker)
• Score the glass (inside the line) and break out your piece. At this point you can position the glass however you need to get a good score line because the pattern line is on the glass.
• Place your cut piece on a second full sized pattern on your worktable.
• Repeat

When you really start to feel confident in this process, you won’t even have to trace the pattern on the glass you can cut directly on the glass with the pattern underneath to guide you.

Next week I’ll talk about what kind of lightbox you need. You might be surprised how simple they are?

Stained Glass Maker's Quick Reference

I know there are a lot of how-to do stained glass out there. I wanted to give those that have taken a class and need a reminder or maybe it's been a long time and you need a refresh list. This is a quick bullet guide to help keep you on track.

• Have two copies of pattern. Cut pattern pieces out of one of the patterns.
• Trace pattern on glass and score and cut the piece. Repeat as many times as needed to cut all pieces out.
• Remember you only need 10 to 15lbs. of pressure to score the glass. You must go from one edge of the glass to the other. You can not stop in the middle of the glass. Cut your hard angles first then go to the other sides.
• After cutting out all the pieces of glass use the grinder to smooth and fit your pieces together.
• Foil all pieces of glass.
• After foiling, place all pieces on the pattern and fit together as tight as possible.
• Tack the pieces in place so they don’t move when you start to solder.
• Flux pieces at the joints.
• Tack solder the front side of the panel.
• Remove tacks and flux and flat solder the back side of the panel.
• Turn panel back to the front and “bead” solder.
• Add metal frame or filigree.
• After soldering, let cool enough to touch, and then wash with dish soap and natural bristle brush to remove any contaminants.
• Dry thoroughly with a paper towel.
• Add patina and wash panel again with dish soap.
• Add stain remover if needed.
• Finally, add finishing compound to panel, let dry and buff off.

Why 0000 steel wool is my best friend for stained glass art.

A grade of steel wool is called an “aught” so when you go to a hardware store to find it you will need to ask for 4 aught steel wool. This stuff is a must tool in your stained glass supply collection. Here are a few reasons to always have some on hand.

·         It can take off oxidation (white scum) off of the lead or solder without scratching the glass.

·         It’s perfect for repair work or clean-up jobs. Scrub the solder joints and damaged area (even the glass) with it to get “time” off of an old window. It’s good for cleaning off smoke damage on the stained glass panel.

·         If you don’t like your patina choice or you have old patina you need to take off you can scrub it off with steel wool and it still won’t hurt the glass.

·         It can take off old paint, marker or sticker residue. Simply rub it over the marked area and it will be cleaned. Be careful if you have a repair or a cleaning job has painted faces etc. If it’s painted and fired you will not be able to scrub it off (because it’s actually a thin layer of glass fused to the pieces) but if it is some other paint it can be taken off with steel wool. Make sure that you actually want to take it off. I suggest to test a corner of the painted area that needs to be fixed or cleaned. Or avoid it by putting masking tape over the painted area that you want to protect.

After using the steel wool to scrub away all that you need to do, make sure to clean it all off (simple soap and water) before you patina or you will have instant rust that will create a brown tint to your patina (unless you like that look).

I want my pattern marks to stay where I put them!

Marker stays well on glass if you want to wait for it to dry. The problem is, who wants to wait for marker to dry. Do we wait hours, days for each mark? It’s just not practical. So there are a few techniques that I’ve come up with to keep us moving forward with cutting and grinding.

I’ve tried all kinds of markers over the years and I found a silver sharpie has much better staying power. I’m not sure what they use that’s so different from the black but it stays so well when it dries sometimes I have to use 0000 steel wool to get it off.

I have also used gold paint pen. It has good staying power but only when you let it dry. Nice thing is it dries quickly.

To help these markers and paint pens stay even better, smear petroleum jelly over the marks to keep it from coming off too quickly while grinding or saw cutting. Make sure to apply a thin layer of the jelly. Excess jelly can get in the inner workings of your saw and bind it up or capture additional grinder grit where you don’t want it.

Why is stained glass worth it?

I talked about educating your buyers on why stained glass demands the price it does but why it’s worth it?

Stained glass takes a skill to design and create that not everyone has. It’s not merely a craft but an artisan craft that has spanned the ages. Many stained glass windows have lasted hundreds of years. If built properly, your windows could be around for generations as well. Use the best designs, tools and supplies to make your windows last forever. So, when you add a window to a home it will be a part of that home’s character for the rest of the home’s life. Here are a few ideas that you can share with your customers.

Stained glass windows last so long you may need to train your clients to think in decades. Is it worth the cost for something that will last 20, 30, 40 years or more and look as good as the day you made it? Make sure to choose a style that your client will love for that long as well. Try to steer them away from matching wallpaper because your window will outlast any wallpaper style.

Stained glass is a great privacy barrier that works better than curtains. It won’t fade, or trap dust and dirt or disintegrate like curtains. Stained glass can work in wet locations where a curtain or blind would not (triple glaze it and it can be in the shower). Specialty curtains can be just as costly as stained glass windows and last much less time, so you can use that as a base for your argument. Not to mention, in my opinion, it’s much more beautiful than curtains because it puts colors all over the room.

Stained glass windows can block intense light better than blinds. Keeping your floors and furniture from fading in the sunlight. You can use clear textures to tone down the light, opaque colors to block but add a glow of light, and use black or mirror to block light completely.

Well-made stained glass will add curb appeal to any home. When you make windows for a front door and sidelights it can bring style and life to a home even before you walk in. For example, a craftsman style home will be apparent as soon as you walk up to it. At night, a colorful stained glass window will glow in the dark and draw attention from all within sight.

What is your favorite argument for why stained glass is worth it?