Glass working tools: names, pictures and what each one is used for

Glass is scored and broken, not cut

This is the single thing to understand, and it explains almost every tool here. A glass cutter does not cut through glass. It puts a controlled fracture into the surface, and the glass is then broken along that line.

That means the score has to be right first time. Going over a score twice does not deepen it, it creates a second competing fracture, and the glass then breaks along neither. It also blunts the cutter wheel on the glass that has already been scored.

One continuous pass, consistent pressure, right off the far edge. You should hear a light hiss rather than a scratching sound, and see a fine even line rather than a white crushed one.

Score once, never twice

A second pass over the same line creates a competing fracture and breaks the glass unpredictably. It also ruins the wheel.

Run the score off both edges

A score that stops short leaves the glass anchored, and the break will curve away at the end.

Listen to the sound

A light hiss is right. A gritty scratching noise means too much pressure and a crushed line that breaks badly.

Break it straight away

A score relaxes within minutes. Break it while it is fresh, or it will not follow the line at all.

Oil the cutter

Cutting oil lubricates the wheel, gives a cleaner score and makes the wheel last far longer.

Score the smooth side

On textured or rolled glass, score the flatter face. The wheel cannot make a consistent line on texture.

Curves, and why glass will not do what you want

Glass breaks in straight lines given the chance, so an inside curve is the hardest thing in the craft. A tight concave curve will not simply break out in one piece.

The technique is to take it in stages: score the curve, then score a series of relief lines from the curve out to the edge, and nibble the waste away in small pieces with grozing pliers. Trying to remove the whole waste piece at once splits the work through the middle instead.

Then the grinder tidies the line. Almost no cut edge in stained glass goes into a panel unground, because the fit between pieces is what makes a panel lie flat.

Score the curve, then relief cuts

A series of lines from the curve out to the edge lets you remove waste in small pieces rather than all at once.

Nibble with grozing pliers

Small bites near the line. A large bite propagates a crack straight through the piece you are keeping.

Outside curves are much easier

Convex curves break reasonably well in one go. Design around this if you can, especially early on.

Grind to the line, not past it

The grinder is for refining a break, not for shaping glass from scratch. That is slow and wastes wheels.

Cut to the pattern, then check the fit

Panels grow as you assemble them. Check pieces against the drawing regularly rather than at the end.

Lead and solder, which need respect

Traditional stained glass uses lead came, and copper foil work uses lead based solder. Both mean handling lead, and lead is a cumulative toxin that is particularly harmful to children and to anyone pregnant.

The practical rules are simple and they matter. Never eat, drink or smoke where you work. Wash your hands thoroughly before you do any of those, since the main route in is hand to mouth rather than breathing. Ventilate while soldering, because flux fumes are an irritant. And keep lead work out of a kitchen entirely.

None of this makes the craft unsafe, and all of it is worth doing properly rather than being casual about.

Wash hands before eating, always

Hand to mouth is the main route lead gets into people. This is the single most important habit.

Never work where food is prepared

Lead dust settles on surfaces. A separate bench, and ideally not a kitchen table.

Ventilate while soldering

Flux fumes are a respiratory irritant. Extraction at the bench or an open window and a fan.

Keep children and pets out

Lead is far more harmful to children, and there is broken glass on the floor whatever you do.

Sweep up lead offcuts

Small lead scraps and solder spatter accumulate. Collect them rather than letting them spread.

Consider lead free solder

It works, it costs more and it runs at a higher temperature. A reasonable trade for some people.

What to buy first, in order

Stage one: cutting

An oil filled glass cutter, cutting oil, running pliers, grozing pliers, a cork backed steel rule, a marker and safety glasses. Plus a decent light box or a window.

Stage two: shaping and fitting

A glass grinder with a standard bit, a sponge and water, a grinder eye shield and a pattern shears. This is the tool that transforms results.

Stage three: assembling

For copper foil: foil, a fid, a soldering iron, flux, a brush and a stand. For leaded work: a lead knife, a lead vice, horseshoe nails and a stopping knife.

Stage four: finishing and fusing

Patina, cement and whiting for leaded panels, polish and a brush. If fusing, a kiln, shelf paper and a firing schedule.

Mistakes that break glass

Scoring the same line twice

The break follows neither fracture and the piece is lost. It also blunts the cutting wheel immediately.

Leaving a score before breaking it

The fracture relaxes within minutes and then will not run. Score and break as one action.

Taking too big a bite with grozers

The crack runs into the piece you are keeping. Small bites, close to the line, working round.

Trying to break out a tight inside curve in one piece

It splits through the middle. Relief cuts and nibble it away instead.

Soldering with a dirty or unfluxed joint

Solder will not flow onto oxidised copper. It beads up and sits on the surface without bonding.

Overheating copper foil

Too much heat for too long lifts the foil off the glass and can crack the glass itself.

Eating with lead on your hands

The main route lead enters the body. Wash first, every time, and never keep food at the bench.

Working without eye protection

Breaking and grinding both throw fragments, and glass in an eye is a hospital visit.

Looking after glassworking tools

Keep the cutter oiled and replace the wheel

A blunt wheel gives a crushed score that will not run. Wheels are cheap and they are consumables.

Store the cutter wheel down in oil

An oil reservoir cutter kept upright dries the wheel out. Down, or in its case.

Keep the grinder reservoir topped up

The bit is water cooled. Running it dry destroys the bit in minutes and cracks the glass you are grinding.

Tin the iron and keep it clean

A soldering iron tip that has oxidised will not transfer heat. Wipe it and re tin it while it is hot.

Clean flux off finished work and tools

Flux residue is corrosive and it keeps working. It causes the white bloom on a panel weeks later.

Sweep the bench and the floor properly

Glass slivers and lead scrap both accumulate. A dedicated brush and dustpan that never goes elsewhere.

Frequently asked questions

What glass working tools do I need to start?

An oil filled glass cutter, cutting oil, running pliers, grozing pliers, a cork backed steel rule, a marker and safety glasses. Add a glass grinder as soon as you can, because it transforms how well pieces fit together.

Does a glass cutter actually cut glass?

No. It scores a controlled fracture into the surface, and the glass is then broken along that score. Understanding this explains almost every other tool, because they all exist to control where the break goes.

Why can't I score the same line twice?

A second pass creates a competing fracture, so the glass breaks along neither line and the piece is usually lost. It also blunts the cutting wheel, because the wheel is running over glass that is already fractured.

What are running pliers for?

Applying even pressure either side of a score so the fracture runs along it cleanly. They have a curved jaw and a centre line you align with the score, and they make straight breaks far more reliable than snapping by hand.

What is the difference between running pliers and grozing pliers?

Running pliers make a score run into a clean break. Grozing pliers have serrated flat jaws for nibbling small pieces of waste away from a curve or an edge, in small bites close to the line.

How do I cut an inside curve in glass?

In stages. Score the curve, then score a series of relief lines from the curve out to the edge, and nibble the waste away in small pieces with grozing pliers. Trying to remove the whole waste piece at once splits the work.

Do I need a glass grinder?

Not to start, and it is the single most transformative purchase. It refines every cut edge so pieces actually fit each other, and a panel only lies flat if the pieces fit. Grinding by hand with a stone is possible and slow.

What is the difference between leaded and copper foil stained glass?

Leaded work uses H section lead came channels holding each piece, soldered at the joints, and suits larger panels. Copper foil wraps each piece in adhesive foil and solders the whole seam, which allows finer detail and smaller pieces.

Is working with lead solder dangerous?

It carries a real but manageable risk. Lead is a cumulative toxin and the main route in is hand to mouth, so wash hands thoroughly before eating, never keep food at the bench, ventilate while soldering, and keep children away.

Why won't my solder stick to the copper foil?

Almost always no flux, or a dirty surface. Solder will not flow onto oxidised copper, so it beads up and sits on top without bonding. Flux the seam properly and make sure the iron is hot and freshly tinned.

What is a fid used for?

A plastic or wooden tool for pressing copper foil down tight onto the glass and burnishing it smooth. Foil that is not properly burnished lifts at the edges and the solder line then looks lumpy and uneven.

Can I fire glass in a pottery kiln?

Sometimes, but the firing schedules are completely different, and glass needs controlled cooling to anneal or it cracks from internal stress. A kiln with accurate programmable control is what matters more than whether it was sold for glass.