Learn How To Putty A Leaded Window

Learning how to putty a leaded window is the final section of this tutorial. I will show you how to make your own cement free putty as well as how to use it.

Cement free?? That's correct! You do not want to use cement, plaster of paris or any thing else that would turn your putty as hard as a rock. Plaster absorbs moisture which in turn causes the putty to crumble and fall out. Portland cement is so strong it attaches itself to the glass, making repairs and restorations very difficult. Plaster and Portland cement are not good to use when you want to putty a leaded window.

If you are using a commercial putty made for stained glass, look for one that does not contain cement or plaster of paris. A good indicator of what not to buy is if the product contains the word cement in the name or description.

Putty is used to seal the space between the glass and lead. It cushions the glass, prevents air and moisture from getting in through that space, and it keeps the glass from rattling. The glass needs to be cushioned to prevent it from breaking. This is especially true when the panel is in a door. If you use cement, it will become extremely hard and gives no cushioning effect at all. After you putty a leaded window, the putty should always remain slightly pliable and have some "give".

How To Make Your Own Putty

Double click on any of the pictures on this page to enlarge them.

Materials needed:

Boiled Linseed Oil
Raw Linseed Oil
Whiting, also called chalk dust or fine grade calcium carbonate powder
Stove black or black coloring for cement or paint.
A container for mixing the putty.
Rubber gloves or, my preference, nitrile gloves.

The linseed oils could be purchased at most large hardware stores like Home Depot or Lowes, but many people are now saying that they can't find both types of linseed oil at that type of store, so getting it online might be your best bet. Do a Google search to find it, or go to Amazon.com and search for it there. Amazon has a lot of linseed oil, both raw and boiled, in different brands, sizes and prices.

The whiting should be available at pottery supply stores or large paint stores, especially those that make their own paint. Also, many stained glass suppliers carry whiting.

When mixing your own putty the proportions of boiled to raw linseed oil is 50/50. Keep adding whiting, a cup or so at a time until it is the right consistency (more about that below). If you want your putty black, add the black coloring at the end. If you do not use black, the putty will be a light beige color.

When I putty a leaded window, I like black putty because it helps to turn the lead black. In my opinion, blackening the lead really makes the colors of the glass stand out, and it also eliminates those bright shiny solder joints.

For my demonstration I used:

1/2 cup Boiled Linseed Oil
1/2 cup Raw Linseed Oil
4 cups Whiting

I initially started out with 2 cups whiting, then added the rest in 1/2 cup increments, until it was the right consistency. I then added about 1 heaping tablespoon of powdered stove black.

Mix it with your gloved hand. It's much like making bread dough. Just keep mixing until the lumps are gone and it is smooth. If you are making a big batch, you can mix it in a bucket and use a drill-powered paint stirrer that attaches to an electric drill, just like a drill bit. Mixing a small batch by hand is easy, but the job gets physically more difficult with large batches, thus the paint stirrer (available from most hardware store...even WalMart carries them!).

When making putty for a leaded window, the right consistency is like very thick pancake batter. If you get it too stiff add a little more linseed oil (both kinds), if it's too thin add more whiting. You really can't go wrong, but you might end up with a lot more than you wanted if you keep adding stuff to get it just right! The picture on the left is too thin, the one on the right is just right.

The "too thin" picture shows it running off the spatula. The "just right" picture shows it slowly oozing off my hand.

When I get ready to putty a leaded window, I like my putty a little on the runny side...like thick pancake batter, because I push it under the lead with a fid. My husband like to push it under with his fingers, so he likes it to be stiff enough that he can roll it up into a ball. What I'm trying to tell you is the right consistency depends on your method of puttying.

Let's Putty A Leaded Window

Materials you will need:

Newspaper
Paper towels
Plastic Fid
Nylon brush
Natural bristle brush
Horse shoe nail
Putty
Whiting
Dust mask
Apron
Rubber or nitrile gloves

To get ready to putty a leaded window, check the window one more time for missed solder joints. Wipe it, on both sides, with a paper towel to get rid of the excess flux. There is no need to wash it, wiping will suffice.

When you putty a leaded window, it is a good idea to cover any textured or glue chipped glass with contact paper. Putty is really difficulty to clean out of textured glass, and it also gets into any fissures or crevices that might be in the glass. On top of that, if you use black putty, it will turn the glue chipped side of the glass grey. The glass is difficult to clean up, so covering it with contact paper first is a real time saver.

This is what glue chip glass (the textured side) looks like if it hasn't been covered with contact paper before you start to putty a leaded window.

Now we are finally ready to putty a leaded window! Lay out some newspaper and put your window on it, front side up. If you don't want to get your hands messy, put on rubber or nitrile gloves.

Pick up some putty with your fid and start pushing the putty under the lead came.

It's going to get messy and you're going to wonder why you ever decided to putty a leaded window (let alone make a leaded window)! Don't worry. It will clean up beautifully and look like a million dollars when you're done.

Finally..the front side is puttied. Now it's time to clean it up before we start on the back side.

The next step, when you putty a leaded window, is to brush it with a plastic bristle brush. Brush towards the edge of the lead, not up and down the lead, to help pack the putty under it. Brushing will also begin to clean the putty off the glass. You can see the wet putty on the brush bristles in the picture.

For this next step you should wear a dust mask. Sprinkle the panel with whiting. Some people use a flower sifter to do this. For me, that's just one more step and another piece of equipment to have around and clean. I just get some whiting in my hand and sprinkle. It doesn't have to be evenly distributed.

Wipe the plastic bristle brush with several paper towels to get rid of the excess putty it picked up. Now, start scrubbing the whiting on the panel. The whiting will start to dry the putty and it will clean up the glass. You can scrub vigorously, just be careful not to pull any putty out from under the lead. Scrubbing in a circular motion works well.

Here you can see how the whiting is cleaning the glass. While you are scrubbing with the whiting, make sure you get off any putty the has gotten on the lead. You do not want putty to dry on the lead. It is very difficult to get off. You want all of the putty under the lead, not on it.

When the glass looks clean, brush off the excess whiting. You can set the panel on its side and tap it on the bench top to remove any left over whiting. You might want to go over the panel with the brush one more time to loosen any whiting and putty that has stuck on the glass.

It's time to trim back the putty, which is referred to as "picking". I use a horse shoe nail to do this. Run the nail along the edge of each piece of lead cutting away any excess putty. You can also use the sharp point of the plastic fid to do this. However, I find a horse shoe nail is easier to use and gives a more precise cut.

I use the fid to clean off the excess putty that I cut back with the horse shoe nail. Another tool the works well is a small flat blade screw driver. Clean off as much of the putty that you can. Then give it another brushing to get rid of any that got left behind.

Cleaning up with a small flat blade screw driver.

At this point, it is a good idea to let the panel sit for a day and give the putty a chance to start drying. The panel can lay flat or you can stand it against something. When you putty a leaded window, you must putty both sides. However, if you putty the back side before the front has a chance to dry a bit, some of the putty on the front will squeeze out. This will give you the chance to pick and clean up the front all over again...so, let it dry if you have the time.

When the putty on the front has had a chance to dry, turn the panel over and putty the back, following the same steps you used on the front. Let it dry again for 24 hours.

Of course all of this is in an ideal situation. There will be times when you just do not have the time to let each side dry before you go to the next step. It can all be done with out drying between each step, but there will be a lot more time spent on re-picking, and the clean up will be more tedious.

After the back has dried for 24 hours, go over both sides and do a final picking. There will be areas where the putty squeezed out and areas you missed the first time.

This is what the window should look like after the final picking.

When you putty a leaded window and have cleaned it up from the final picking, the next step is to vigorously scrub it with a natural bristle brush. Horse hair and tampico are two types of natural bristle brushes. I get mine at our local tack shop (horse supplies). The scrubbing will darken the lead and solder joints.

Here is the last step when you putty a leaded window. Using a paper towel and cotton buds, go over the glass and clean off anything left behind. The glass should sparkle when you are done. If putty or black get down in the fissures that you find in some glass, alcohol will loosen it up. You may need to use a needle to get the remainder out.)

One final note...if you covered any of the glass with contact paper before you puttied, don't forget to remove it when you are done with the final brushing.

Congratulations...you've learned how to putty a leaded window and now you will have a stained glass window that you can be proud of. Send me a picture when you are finished. I'd love to see it.

If you have any questions or comments on how to putty a leaded window, please Contact Me

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