SLIDESHOW: Cementing Leaded Stained Glass
Lead stained glass projects refer to the type of bracing used to hold the glass beads and pieces together, not the glass itself. Lead stained glass projects use a H-shaped type of molding, with grooves on both sides, called lead came. The glass pieces slide into the grooves on either side.
Because there are differences between the glass and the grooves (referred to as “the heart”) of the lead came, a special type of cement is used to fill the gaps and hold the glass in place without breaking it later. This cement has nothing to do with Portland cement, but is a blend of linseed oil and whiting, used by the old masters to cement leaded lines and glass together.
Putting Stained Glass Pattern Together
Every stained glass project begins by sketching the pattern on heavy stock paper, and deciding what colors will go where. These pattern pieces are numbered and cut. These pattern pieces guide the scoring, grozing, and grinding of the glass.
When it comes time to assemble the pieces of glass into the finished project, a temporary frame is set around the piece. I use wood to frame the project while I work, setting the glass and outlines with horseshoe nails driven into a flat, solid piece of wood.
Adding Lead Came
Working with lead came is interesting. There are different sizes, but your glass needs to fit into the grooves on both sides of the came. Cut the glass too close, and the fit will be loose and gap-filled, cut too wide, and you will have to grind the glass down to fit. Just remember you can always grind more off, but you can't uncut glass.
Making the lead lines fit with the original pattern is a bit of an art in itself.
Adding the Outer Lead Framing
As you finish each side, you can get to the point where you wrap the entire piece in an outer lead border, which will frame the finished piece. After this step, we will solder each of the lead lines to each other and the frame, for stability.
Stained Glass Cement
The grooves of the lead came that contain the edges of the glass pieces is cemented. Most people use plaster of paris, because this is convenient and easy to find. I take a slightly different approach. My lead line cement is made from a combination of whiting (calcium carbonate), raw linseed oil, and boiled linseed oil. This is the classical way to make stained glass cement. These ingredients are not so easy to find, which is why very few people use this old methodology.
The main disadvantage to using plaster of paris for the lead grooves is there is no give to the glass once it is assembled and dried. This makes the glass more susceptible to cracking. The linseed-whiting mixture is solid, but is not rigid against the glass, which provides longevity to the piece.
Scrubbing Excess Cement
The excess cement is scrubbed away with a plastic bristle scrub brush. Everything that remains in the grooves will dry and set the glass. The excess cement can be saved for future use in an airtight container, and rolled into the next batch.
Dusting With Whiting
A dusting of whiting is added to each side of the piece, and brushed away with a horsehair brush. The calcium carbonate helps set the cement in the groove of the lead lines, and accelerates the drying process. The horsehair helps polish the glass.
Remove Excess Cement
In this step, we remove the last of the excess window cement that has had the whiting applied, using a pencil. The graphite helps blend the color of the cement to the lead soldering. After this step, we use our horsehair brush to remove the extra cement and polish the glass.
Finished Stained Glass Project
After the piece has been set and polished, it is ready for sale.