With much fear and trepidation, I have finally started to re-glaze my windows. A lot of what I have learned about windows is from Terry Meany's book Working Windows and some other sources around the internet that I think I have mentioned before. I was intimidated at first but there really isn't much to be afraid of. With a little practice any DIYer can become a passable glazier!
Since I am glazing the sash in situ I bought a gallon of Abatron's Sarco Dual-Glaze. It is apparently the best glaze out there. Dual-Glaze has a brother called Multi-Glaze in case you have the luxury of re-glazing your windows in a workshop. Multi-Glaze skins over and can be painted in a few days but cannot be used on installed sash. Dual-Glaze takes 2-3 weeks to skin over but works for installed sash. DAP '33' is the one you'll find in the hardware stores. I haven't used it but I suppose it's ok too. It is the glaze Terry mentions in his book because it is widely available. I have also heard there is glaze in a caulk-type tube but it sounds more like a quick repair/stop-gap option.
I started on the kitchen windows in the back of the house. I figured if I really screwed them up, nobody but skunks, birds, squirrels, cats, prowlers, contractors, and frequent guests would see them.
I dipped my hand into the oily putty and started forming a ball with it just like in the pictures. It was messy and stuck to my fingers. I tried to jam it into the rabbets with my thumb. It wanted to stick to my thumb more than the window. Once I got enough slopped onto the window, I put the knife onto the glass and pulled it down just like I had seen online. It kept pulling up and tearing under the blade as the knife passed! I was so frustrated and stopped after 2 lites knowing that Jim O., a real life window glazier, was coming into the office the next day for an appointment.
Jim told me that I need to knead the putty like dough in my hand for a few minutes, not a few seconds. It needs to get warm and soft--especially in the cool temperatures we've been having. He also said not to be afraid to press hard on the glaze--saying I wouldn't break anything. He said that I could apply the glaze with the base of my palm and told me to make sure I always slide my knife off and not lift it off. One final tip: make sure my knife is stiff, perfectly clean, and the corners are sharp.
The palm application technique he recommended didn't work well for me because of the awkward angles on the ladder. But things definitely went better the second time around. In addition to heeding Jim's tips, I put on latex rubber gloves which the putty doesn't really stick to, used mineral oil to clean the knife blade, kept the blade of the knife warm while kneading the glaze by holding it under my arm, and primed the sash for glazing by rubbing all of the bare wood with pure linseed oil on a rag (to keep the wood from absorbing the putty's oils). I also tried to work the putty as soon as I could because I noticed that the cold glass cools the glaze down quickly. When all was said and done, I even had a couple sections where I left a perfect line of glaze in one swipe with no repairs (except for the corners). I thought I was somebody!
During my third outing I discovered why glazing is as much art as it is science. I realized I had the science part down and needed to master the art. I decided that glazing is a zen-like yin yang combination of everything: science & art, hard & soft, frustrating & peaceful, power & finesse (which is a fun lacrosse drill by the way). Delicately balancing the yin and yang of window glazing becomes a meditative DIY project.
What follows is:
The zen of glazing
1. Hold the ball of putty near the edge of the glass, push the blade of the knife through the ball to the glass and then smash the putty into the edge and clean it off the knife by sliding the knife up along the edge of the wood. Don't jam too much or too little putty in--just a little extra is best.
2. Start the knife by sliding it down to the glass from the corner at the desired angle. Apply moderate pressure to the corner of the knife that is against the glass by holding your finger close to the glass. Not too much pressure but not too gentle either.
3. Slide the knife down the glazing putty keeping the corner-of-the-knife pressure on the glass constant for the entire length. While drawing the knife down, try to feel the knife float across the putty while at the same time feel it glide along the edge of the sash for balance. I have noticed that too much pressure causes the glaze to pull up so I focus moderate pressure onto the glass and try to balance the knife between floating on the putty and pushing against the sash. This is the most zenny part.
4. When you start to approach the end of the glass, slide the knife tip up from the glass towards the corner of the sash while still keeping the knife tilted at the same angle. This will create a nice and sharp looking corner. This is definitely an art and requires some time to develop so be patient. I'm still learning it myself. Fake it til you make it by shaping the corner with the flat face of the knife blade and/or with gentle finger pressure.
5. If you've done it right you should have a curly strip of extra glaze ready to fall off. It is wise to keep your hand with the ball of putty in it under your knife so that any glazing falling off can be saved instead of falling into the dirt and ending up being wasted. Add it back to the ball of putty and work it around a bit so it mixes back in.
6. If you have a fully cleaned out rabbet, you want to be able to see about a 1/16th of an inch of the backside of the interior muntin through the glass. If the putty is too wide, repeat steps 4 and 5 until the glaze is trimmed back far enough to see the backside of that muntin. Another chance to practice that zen meditation! Later you will be painting the glaze and want the paint to overlap the glass by about 1/16th of an inch to seal the glazing edge from the elements. When all is said and done, you don't want to be able to see anything on the outside of the window from the inside (if you are spot glazing, you may find yourself at the mercy of previous painters and handymen who have layered on material that becomes wider than it should be over time and to maintain order and balance you will have to go wide as well--like in the photo below on the right--even though it may drive your perfectionist-self nuts).
A very gentle swipe of the back of the finger in the opposite direction that the knife went can help smooth any imperfections out. Paint the glaze after it has skinned over with either oil-based or water-based paint (no primer--at least for the Sarco stuff).
This really seems like a scary project, but if you just do a little research and then dive in, you will find that it is really not that bad. Follow the tips here and you will come to see what I mean about the zen of glazing.