How to make a stained glass pattern

01

Measure the opening

Start from the space the panel will fill: a window, a door light, a cabinet front, a frame. Measure its width and height in more than one place and take the smallest of each, because the panel has to go in.

What you draw is the panel's outside edge, its finished size. If it sits in a frame or a rebate, allow for what will cover its edge before you draw.

Then draw that outline: a rectangle, a round top, a Gothic arch, a circle, an oval. An arch takes its rise from the width: a round top on a 500 mm panel rises 250 mm.

02

Choose lead came or copper foil

Decide how the panel will be built before you draw, because the technique changes the drawing. In lead came the pieces sit in strips of lead: the lines are wide, 6.4 mm (1/4 inch) on most panels, and each piece is cut 1 mm short of its line to leave room for the came's heart. In copper foil each piece is wrapped in copper tape and the seams are soldered: the lines are about 3.2 mm (1/8 inch), and the glass is cut almost on the line.

Lead came is the usual choice for windows and doors; copper foil for small, detailed pieces, lamps and work in three dimensions.

03

Draw the big lines first

Begin with the lines that make the picture: the outline of the subject, a horizon, the border. Then add the lines the glass needs. Every line becomes a lead, so draw fewer than you think: a stained glass design is simpler than the picture it comes from.

Let every line go somewhere. Glass breaks along a score from one edge to another, so a line that stops in the middle of a piece can't be cut. Run each line on to another line or to the edge of the panel.

Where lines meet, let two or three meet, not more. A joint where 4 or more leads meet is hard to fit and pools solder, and its heat can crack the glass beside it.

Draw what repeats once: one petal of a rosette, one half of a symmetrical window, and mirror it.

05

Number the pieces and choose the glass

Number every piece. The number goes on the pattern piece, on the glass cut from it and on the plan, so they can be matched on the bench.

Then choose a glass for every piece and record it on a plan: a letter in each piece, and a key that says which glass each letter is. Where a glass runs one way, with streaks, reeds or a grain, mark the direction, so its pieces are cut the same way out of the sheet.

Try more than one colour scheme before you buy glass. The same leadwork can be a sunset or a night sky.

06

Print the pattern full size

The pattern you cut from is the full-size drawing, the cartoon. Print it at 100%, never 'Fit to page', tiled across as many sheets as it takes, and tape the sheets together by their marks.

Measure something you know before you cut: the Studio puts a 100 mm square on page one. A printer that prints 1% large makes every piece 1% large.

Cut each piece on the inside of its line. The Studio prints each line as wide as the strip your pattern shears take out: 2 mm for lead came's heart, 0.8 mm for copper foil.

07

See it in light before you cut

Glass in light is not glass on paper. A deep blue goes almost black on a dull day; an amber glows when the sun is low. Look at the panel in the light it will hang in before you buy and cut the glass.