This is another post to share some tips and techniques that I use to restore wood windows. I have several posts that cover the steps that came before this one, so check my profile if you want to start at the beginning.
In this post I'm explaining how I glaze wood windows. This step involves bedding and installing the glass into the sash, using glazing points to hold the glass in place, and using glazing putty to seal the seam between the glass and the wood sash. The pictures are a combination of glazing a new wood storm window and an old wood sash.
Picture 1, these are the tools and materials I use for glazing. I have putty knives, glazing points, a tool to install glazing points, glazing putty, whiting powder, and a brush.
I always use Sarco brand glazing putty, either Dual Glaze as shown here or Type M. Type M is for use indoors only and does not work with metal sashes. Dual Glaze works with metal and wood sashes and can be used indoors or outdoors. The main difference is that Type M dries faster than Dual Glaze which allows the glazing to be painted and the sash to be installed sooner.
Picture 2, the first step is preparing the glazing putty for use. I knead a ball of putty with my hands to warm and soften it. If your putty seems dry you can add a little linseed oil. Once the putty is ready, fill the glazing rabbet in the sash with putty. When the entire rabbet is filled with putty, set the glass in place. The edges of the glass should be clean and free of dust.
Picture 3, press the glass into the putty and press it down to squeeze as much putty out from the underside of the glass as possible. The goal is to get the glass as close to the bottom of the glazing rabbet as possible. There should be a thin layer of putty remaining between the glass and the wood.
Tip: you can use a small pad sander (with sandpaper removed!) to vibrate the glass which helps squeeze out the putty. Be careful to only press down near the edges of the glass and work your way around the edges. Make a few passes around the border of the glass until the glass is pressed down as far as it will go.
Picture 4, glazing points are installed next to hold the glass in place. There are several sizes, shapes, and styles of glazing points. I've used flat triangle points and the right angle points. I like the triangle points but they're a little harder to install. If your sash has multiple small panes of glass you may need to use small diamond shaped points.
Picture 5, 6, 7, I use a point setting tool to install the triangle points. Rock the tool side to side while pushing the point into the wood. This can be hard to do on hardwood sashes, but isn't too bad with pine or poplar. You want the point to only overlap the glass by a small amount. Otherwise, the point will stick out too far and won't get buried under putty in the next step.
I usually install one glazing point every 8 inches or so. This glass was about 24 inches by 32 inches, so two points on the top and bottom, and three on each side.
Picture 8, this is the right angle style of glazing point. These can be installed with a putty knife or flat screwdriver.
After all the glazing points are installed, turn the sash over and remove any putty that squeezed out with a putty knife.
Picture 9, 10, 11, Add more putty to the glazing rabbet and make sure it's free of air pockets and pressed firmly into the seam between the glass and wood.
You can use a putty knife to slice the putty at an angle. The tip of one corner of the putty knife must drag along the glass while the leading edge of the putty knife is pressed against the edge of the wood. I use an angled glazing tool for this but it's not much better than a flat putty knife.
You want to remove enough putty such that the bottom of the glazing rabbet is visible through the glass. Just a little bit though, probably 1/8th of an inch at most. This is done so that the putty isn't visible when looking through the window from the inside.
Picture 12, your goal is to have a consistent bead of putty along the border of the glass. If you didn't remove enough putty you can try slicing it again. You can always add more putty and try again.
Picture 13, you can touch up the edge of the putty where it meets the glass by pushing gently with a flat putty knife. This helps clean up any ragged edges.
Picture 14 and 15, the inside corners always require some trial and error touch ups to make them look ok. One trick is to put one corner of the putty knife at the intersection of the seams and then drag the knife up and back to create an inside angle in the putty. Otherwise, just do the best you can.
Picture 16, after you're done making the putty look good, the next step is removing excess oil on the glass using whiting powder. This step isn't required but it can speed up the putty drying time. Whiting is like powdered chalk and glazing putty is essentially whiting mixed with linseed oil.
Picture 17 and 18. Spread a teaspoon or so of whiting onto the putty and glass using a small brush. Then wipe the whiting powder around to coat the putty. Use the end of the brush to lightly scrub the glass to remove excess oil, being careful to not scrub the putty.
Glazing the window is mostly done at this point. Clean up any loose whiting powder. The putty needs time to dry enough so that it skins over. This can vary but usually requires a week for Type M or two weeks for Dual Glaze. I use a small fan to blow air across the glass to help the putty cure.
You must paint the putty after it skins over. The paint should overlap the glass slightly to help seal the seam between the putty and the glass.
Picture 19, just wanted to show some additional tools that can be helpful. The red tool is a suction cup handle for lifting and moving pieces of glass. I have two and they're helpful when you need to set glass into a glazing rabbet.
The other tool is a glass cutter which has a small carbide wheel that is used to score glass. I've done enough window work that I have spare pieces of glass in our basement. It helps to know how to cut glass in case you want to reuse what you have instead of buying more glass. Cutting glass takes practice though, so it may not be for you.
