Cementing Lead Came
Weatherproof Your Stained Glass Panel
Up until now your panel has been a bit delicate and easily harmed. The cementing stage will make it strong and waterproof.
A black putty mixture is pushed under the lead came, which hardens to make the stain glass panel firm.
What you need
- Tub of black cement
- Piece of toughened glass or a board for mixing
- Mixing knife
- Latex gloves
- A couple of scrubbing brushes, nail brush or old toothbrush 6. Whiting (chalk powder)
- Dustpan and brush 8. Newspaper 9. Dust mask.
If you want to mix your own cement, replace the ready-made black cement with:
- Tub of all-purpose putty
- White spirit (UK) = Mineral spirits (US, Canada) = Mineral turpentine (AU/NZ). Generic name = paint thinner.
- Black powder paint.
Cementing A Lead Came Panel
1. Mixing the cement
If you’re going to do a lot of lead came panels, it’s cheaper to make your own cement. Otherwise you can buy a pot of ready made black cement at any stain glass suppliers.
– The ready made cement has to be mixed for about 15 minutes. It’s easier to take some out and mix it with a strong knife on a board.
– To mix your own, get some household putty and knead it until it has no lumps and is malleable.
– Put it on your mixing glass/tile and mix in some white spirit (mineral spirits, paint thinner) with the mixing knife, until it’s fairly runny.
– You don’t want it too stiff otherwise it’s difficult to push it under the flanges of the lead.
– When it’s mixed together, add a spoonful of black powder paint to colour the putty black.
2. Brushing cement under the stain glass lead came
– Place your panel on some newspaper.
– Using either an old toothbrush or a scrubbing brush, start pushing the cement under the leaves of the lead. Plastic nail brushes are great for this.
Work the cement in across the leads. If you brush up and down the length of the lead you will remove the putty you’re trying to put in.
– Don’t worry if you get more black cement in one side than the other, it’s normal and adds to the texture of the panel.
– If you have enough time, it’s best to cement both sides at once and clean up afterwards.
– You can do one side at a time as long as you clean it thoroughly before stopping. If you leave the cement on too long it starts to harden and is difficult to clean off the lead came.
3. Trapping the cement under the lead came
– Scrape away the excess cement with the fid. This can be reused if sealed tightly in your putty pot.
-Use the flat end of the fid and gently push down each side of the lead onto the glass.
– You can break your glass at this point, so don’t push too hard.
– Don’t worry too much with this if you’re using narrow lead – 3/16 (5mm) – as there’s not enough width to push down.
4. Cleaning up
– Sprinkle with whiting (chalk dust) and rub over the whole panel so the chalk dust absorbs the linseed oil.
– Trace round each glass shape with the ‘beak’ of the fid to loosen the spare cement.
– With firm pressure, brush this spare cement off with a scrubbing brush. If you can find one with short bristles they work very well. As above, brush across, not along the length of the leads.
– Make sure you get all the putty off the lead came before it hardens and becomes tricky to remove.
– Turn the stain glass panel over and do the same on the other side.
– Some of the putty will squeeze through, but don’t worry as you are yet to do the final clean.
5. Drying the cement
– Once you’ve cleaned all the leads and glass with the whiting you’re finished for now.
– Leave the stain glass panel for about three days so that the cement can dry and harden.
Here’s a 48 second video showing how to cement stain glass. There’s a couple of things to watch out for:
– Usually the cement is a bit runnier than this.
– Using a knife isn’t recommended, as you might scratch the glass and it’s not very flexible for pushing the cement.
But all the same, it might be helpful and give you some idea of the process.
Short video showing how to cement a stain glass panel
Once your panel has dried for 2-3 days you’re ready for the final stage Cleaning and Polishing.
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