Fresh-cut stained glass is sharp, jagged and almost never the exact shape on your pattern. A glass grinder fixes both problems. Amaya Jade walks through it in her stained glass for beginners series, grinding the pieces of an iridescent wing panel so they fit the pattern and are ready for copper foil.
This is step two of four. You cut the glass, grind it, foil it, then solder it.
Do you need a glass grinder?
For a first small project, maybe not. Grozing pliers can nibble off a sliver of glass that sticks past the line, and a sanding stone can dull a sharp edge. That gets you through a simple stained glass suncatcher. But curves, tight inside points and pieces that have to meet neighbors on every side are slow and frustrating by hand. A small hobby grinder pays for itself by your second or third panel. Pick one with a water reservoir and a sponge or self-watering bit.
Grinder bits: 3/4 inch vs 1/4 inch
Most grinders ship with a 3/4 inch bit. It handles straight edges and outside curves, which covers most of the work. A 1/4 inch bit reaches into tight inside curves and the V of a deep notch. Bits are diamond coated and wear in bands. When grinding takes force, raise or lower the bit to a fresh band before you replace it. Take the bit off when you finish. Amaya never did, and hers rusted in place.
Safety: eyes, water and fingers
- Eyes. Wear safety glasses every time. Chips fly off the bit.
- Water. Never grind dry. Water keeps glass dust out of the air and stops heat from cracking the piece. With enough water there is no dust.
- Fingers. Cut-resistant gloves that fit well protect you from edges. Knock the sharpest points off first so you are not gripping a blade.
How much to grind
Grind to the inside of your pattern line, not past it. Copper foil and solder add width to every seam, so a piece that matches the outside of the line will crowd its neighbors. Check against the pattern often. A sticker pattern on the glass makes this easy, because the line moves with the piece and the water does not lift it.
Done looks like a smooth, matte, frosted edge all the way round. Foil grips that texture much better than a shiny cut edge, which makes the finished panel stronger.
Common grinding mistakes
- Grinding too long. A few light passes beat one long press. You can always take more off.
- Chipped edges. Too much pressure or a worn bit. Ease up and let the bit do the work.
- Rounded corners. Keep the glass flat on the grid and hold it still at points. Rocking it rounds them off.
- Coating chips on iridescent glass. Leave the sticker on to protect the edge.
Caring for your grinder
Change the water when it turns milky, and replace the sponge when it stops wicking. Let the reservoir dry to a damp sludge, then scrape it out. Never pour grinder water down the sink. The glass settles like sand and clogs pipes. Dump it outside.
