How To: Paint a Wood Window Sash

By Scott Sidler • October 14, 2013

Old WindowAfter all the hard work is done restoring a wood window, there is one final step: painting your window sash. Painting a window is by far the most important part of the process because it protects all the work underneath. It keeps sun, rain, dirt, insects, air and anything else from harming your window.

Without paint, glazing putty is no good after only a couple months, the sun’s UV rays begin breaking down the wood fibers of the window immediately, water will cause corrosion of your glazing points.

Without paint, your window will fail quickly. But you already know that you have to paint your windows, right? Maybe so, but there is a very specific way that historic windows should be painted to both protect their parts AND ensure smooth operation.

Here are my 5 rules for how to paint a wood window sash.

1. Don’t Paint the Sides

The sides of the sash that slide up and down in the jambs should be left bare. No primer and no paint. This may sound odd, but it has been in practice for well over 200 years. These areas are not seen or readily exposed to the elements so there is no cosmetic reason to paint them, but there is a more practical reason NOT to paint them. By leaving these areas bare you allow both rails (horizontal parts of the sash frame) and both stiles (vertical parts of the sash frame) to expel moisture.

How to paint wood window
Unpainted sides and bottom on old window sash

With these sections bare, the entire sash is able to dry out if it should happen to get wet. Bare wood breathes much, much better than primed and painted wood.

In addition, these parts of the sash slide against the window jamb and if they are coated with paint (especially latex paint) they will stick and be extremely difficult to open and close. Leave it bare.

2. Don’t Paint the Bottom or Top

For the same reasons as above the top of the upper sash and bottom of the lower sash should not be primed or painted either. These parts are not visible when the window is closed and therefore not exposed to the elements. Again, this will aid in the window’s ability to dry out. Not much else to say about this, so let’s move on.

3. Use Oil-based Primer

For the best performance use an exterior oil-based primer. I prefer Kilz Complete in my shop because it is hides very well, goes on easily and sands down nicely. The sash should be primed and lightly sanded with 220-grit paper to smooth out the surface before installing the glazing putty.

Use a brush and work the primer into the wood. Spraying on primer is fine, but be sure to work it in with a brush as you spray. Brushing ensures a better bond between the wood and primer than spraying alone.

4. Apply 2 Coats of Quality Paint

Whether you decide to go with oil-based paint or water-based doesn’t matter to me. The point is the get at least two coats of paint on the inside and outside. Don’t skimp on this paint either. Use a top-notch enamel paint. I prefer Sherwin-Williams Porch & Floor because it is an easy to work with water-based paint and since it is formulated for floors it gets very hard, very quickly.

The technique for painting your window sash is difficult to describe in a blog post, so I’ve put together a short video to show you how it should be done.

Check out the video below and don’t forget that you can get more videos like this by subscribing to our YouTube channel.

5. Finishing Up

Once the windows are painted let them sit aside and cure for at least a few days. This may sound pretty elementary and I’m sure you would never try to put windows with wet paint back in, right? It’s not about the windows being dry. It’s about the paint having time to cure.

Water-based and oil-based paints can take up to 30 days to fully cure. Until that time the paint is more prone to being damaged by scuffs, knicks, and water. Don’t try to wipe down new latex paint or clean it until that 30 days has passed. Otherwise, you run the risk of messing up your paint job.

Once the paint is cured, enjoy the finished product by opening those windows as much as you’d like. You deserve it!

If you have more questions about the rest of the process of restoring a wood window visit my resource page How To: Repair Old Windows

 

Share Away!

84 thoughts on “How To: Paint a Wood Window Sash”

  1. I love all your resources and tutorials. I am fortunate to have knocked out a window to install and door to the deck and have been taking my time cleaning, removing and filling rot, and glazing and painting windows one at a time in my shop. We live in savannah, similarly wet and humid to y’all. As I go along I’ve had to double back and fix previous windows because in the rain or summer outdoor condensation eventually is getting under the paint where it overlaps the glass. I’ve tried freehand, masking and removing while wet and dry, over painting and scraping with razor … I’ve tried 1/16” overlap and 1/8” overlap and it all fails on the windows that are facing the neighbors house where it most often super humid, shady and sticky. I’m using sherwin Williams emerald urethane enamel paint. Clean, cute, prime and paint. I let them dry and set indoors for a few days too. Any advice to avoid the overlap getting water under and just peeling away? I’m at my wits’ end. I am considering running a tiny bead of silicone to seal the glass to the glazing at the bottom edge of each light at this point. I’ve asked all my buddies, family, neighbors …. I appreciate any tips or thoughts on my dilemma. Thanks!

    1. Stay away from the silicone. I have the same challenge down here in Florida. I found that cleaning my glass thoroughly with denatured alcohol has drastically improved my results, but I’m still testing because the issue hasn’t been completely eliminated.

  2. I am staining a 100 year old window the will be used as a table. I have deglazed and removed the window panes. I have sanded the entire thing down to the natural wood. My question is, do I still use oil-based paint primer where the glass sits before bedding the glass or can I use a wood conditioner, then bed the glass, and finally stain the window? Thank you, in advance, for your feedback!

  3. Scott, enjoyed reading about sash painting and found the tip about not painting the edge sides and top and bottom sides of the sashes informative. The tops and edge sides weren’t painted but the bottoms were on my 1930’s Chicago area bungalow double hungs. Not sure how long that was going on, but windows are in good shape and I’ve followed this practice, but will consider your advice going forward for the bottoms. I have wood storms and wanted to know if you also recommend not painting the bottoms of the storms. Mine are offset so the bottoms seem like the only section you can leave unpainted, but there will be snow sitting against them in the winter and they will be exposed to rain thus sitting in water at times. So, im concerned that because they will be sitting in water it will wick up and cause more harm than good. Thanks

    1. Hi Dave,

      Thanks so much for sharing your current situation! Honestly, our best recommendation would be to use our online directory ( http://www.thecraftsmanblog.com/directory ) to find a licensed preservationist in your area who can take a look in person and provide an accurate recommendation from there.

      Best of luck to you!

      -Alyssa at The Craftsman Blog

  4. I have started my restoration project following your directions to the best of my ability and budget. I have removed my windows, and while my husband is working on those, I have been trying to sand the window jambs (the area where the window slides just in case my vocab is wrong), however I can’t get the paint to budge with sand paper. Do you have any advice on the best way to sand the jambs?

  5. The process causes the paint to separate from the wood so that it can easily be removed using a paint scraper.

  6. As an old home restoration contractor I disagree about not painting the bottom edge of the sash. Too often, especially up north with snow, lowest sash sitting in wet sill wicks up water into sash. End grain f rails should be sealed as well as beveled bottom of sash in wood storms and o lowest double hung sash.

    1. I 100% agree with Reed, the bottom sash will rot away, not sealing, painting is VERY POOR advice!!

  7. Hi,

    I am working on reglazing and painting my 1898 Victorian home windows and I have a question about paint brushes. All of my windows on the second and third stories are intricate with a diamond pattern on the top sashes with over 25 lights on a single sash. I’ve been using a 1″ sash brush, but was wondering if there’s a better (or smaller) brush for painting windows with great detail. I’ve searched online and cannot find a sash brush less than 1″. Thanks so much!

  8. I see that you suggest that I don’t prime and paint the sides of the windows. Is it okay to stain the sides? Or is it better to leave them totally bare? I’ve just replaced rotting wood on several of my rounded windows. I live in a 1937 house in Wisconsin. On one of the windows, I had new wood put in along the bottom third of the windows where it was rotted beyond repair. So now I have bare wood.

    I’ve primed and painted the outside. I’ve stained the inside. Right now, the sides are bare.

    thank you

        1. I don’t recommend staining the exterior of a wood window. It was never done historically and doesn’t perform well. It also needs a ton of maintenance. Stain the interior sure but keep the exterior painted if it is a putty glazed window.

    1. Hi Scott,

      I’m in Long Beach California in a historic district and I’m currently have some wood ssh windows made for my Spanish revival home. Here are my two questions:

      1. I see that you recommend Sarco putty for the glazing. The people making my windows use Wonder Putty glazing compound. Is there any difference? They both require the use of an oil base paint.

      2. I plan on using an oil based primer (Zinsser Cover Stain) and then a high quality latex such as Benjamin Moore, Sherwin Williams or Dunn Edwards. If I do use a putty that requires an oil based paint, could I just go over the putty glaze with the oil based primer and then paint over the glazing with a water based latex finish coat?
      Or do I need to use an oil based paint on the just the putty glazing, then go over everything with a water base primer and finally go over everything with a latex water based finish coat?

      Thanks

      Tim

      1. I’m not familiar with Wonder Putty but most linseed oil putties (Sarco included) actually do not require priming and can be coated with oil or latex. We prime the sash with oil based primer the glaze the top coat with 2 coats of latex paint with fine results.

  9. In the video, you are painting a window that’s sitting in your workshop. But…how do you paint a window that is hung already? Are there any tricks to painting the little bits that are facing away from you or between the windows? Mine is a single-hung (only the bottom slides up and down), so there’s a bit of the inside of the top window that’s basically inaccessible from anywhere, and visible when the window is open. Since the window was natural wood, and now it’s painted white, that’s quite a contrast. Is there anything that can be done to paint those overlapping sides?

Leave a comment!

Keep the conversation going! Your email address will not be published.

*

This site uses Akismet to reduce spam. Learn how your comment data is processed.