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How To: Paint a Wood Window Sash

How To: Paint a Wood Window SashAfter 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

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96 thoughts on “How To: Paint a Wood Window Sash

  1. Hi Scott,
    Thanks for this article and all of the information on your site.

    We are restoring the original 6 light wood window in our house that have interlocking aluminum weather stripping and spiral balances.

    After scraping off the old paint I am wondering whether or not to prime and paint the 1/4 in on the face of the sashes where they rest in the tracks. Any recommendations?

    Finally I was curious, can one paint the interior facing side of the sash before bedding the glass? Or does the paint on the interior also need to overlap onto the glass?

    Thanks in advance!


  2. 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.

  3. 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!

  4. 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 ( 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

  5. 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?

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

  7. 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!!

      1. Now Im confused. I am stripping and repairing fixed sashes. They all have a rabbet around the edges for moisture to run down. It appears the bottom edges were not painted originally (circa 65) nor the inner frames. The sills are stepped with the addition of an internal groove to stop ingress of rain beyond a certain point. Now I have rot at the bottom corners of the sash and some on the sill. I think this not because the edges were not painted but the fact that someone caulked between the bottom edge of the sash and the sill where there is a small 10mm step/gap. Thus any moisture or condensation running down the insides of the sashes or frame accumulated at the bottom and could not get out or dry out. So to paint or not paint the edges there appears to be two camps equally supported, so what to do?????

  8. 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!

    1. That size just walk into an art store (like a Blicks or something) and get a paint brush there. Brushes are brushes and there just isn’t a call for sash brushes that small normally.

  9. 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?



      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.

  10. 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?

  11. Hi, is kilz complete still the best primer if the sashes aren’t completely bare and they have some residual/peeling paint on them? I known it’s best to get down to bare wood, but I did the best I could under time constraints. Thanks!!

  12. Should the glazing rabbets be primed and painted or just treated with linseed oil? If linseed oil, when and how is this done?

  13. Hi Scott, thank you for this wealth of information. Restoring my wood windows in my DC home and man its a little overwhelming at first. Another brought this question up but wanted to expand a little more. I understand the windows should be painted with a hard enamel. I am also painting the jambs. I have chosen a water based hard enamel to avoid VOCs in my house while painting. Is water based enamel ok for the jambs as well? I am worried about the windows sticking. I have not painted the sides of the sash as you stated.

    1. It should be fine Patrick. After the paint has cured you may want to add some beeswax or finishing wax to the jambs or sides of the sashes to help prevent any sticking.

  14. I have a south facing window that is bare wood on the outside sill and has thin horizontal cracks. Last year I primed with oil based primer and painted two top coats of outdoor window paint and this spring it’s nearly bare wood again. Do I need to use some sort of conditioner to the wood first to get the primer and paint to stick??

  15. I like this article on the painting of the sashes. But what about the frame where the sash will run on the frame. this is visible, should it be painted?

    1. Russ, painting of the jamb depends on what was there originally. Windows in some regions had painted jambs and other were left bare and waxed or treated with linseed oil. Try to determine what treatment yours had and stick with it for the best results. If you do decide to paint then make sure to use a good hard curing enamel paint that will help prevent the sashes sticking in the jamb.

      1. Originally…… not sure. Now it is painted and a bit sloppily. I’m in the northwest suburbs of Chicago in a 1894 Victorian. Double hung windows with fairly functional lower sashes and mostly stuck upper ones. I have triple track storm on the exterior that will eventually by replaced with wood storm/screens or at least the bare metal will be painted to match the color scheme. The wood seems to be in good shape on the sashes and the jams. I would to restore the windows to full double hung function and weather strip them. Primary concern is to have them look good and be operable. I guess I could

        1) Oil prime the jams only
        2) Leave (rather make) unpainted the wood and wax them
        3) leave unpainted and linseed oil them.

        What is best for function in the Midwest with harsh winters and hot summers?

        1. Russ, chances are when you get the top sashes out you’ll see what the original treatment and can proceed accordingly. Options 2 & 3 would work well, but if you do paint don’t just prime. Probably a good oil-based enamel finish paint would work well.

  16. Hi,
    I’ve bought a victorian terrace all with original sash windows. You can see all the previous years thick paint. Is it best to remove all the old paint as it’s starting in areas to flake? Then repaint it? Many thanks

  17. Hi Scott,
    My sash restoration is almost done. I’m in the process of glazing & paint. It’s the bathroom window so I use the privacy glass with pattern which the glazing compound stuck to the crevasses. The cleaning will be tidy and I’m concern that it could be more messy with the paint too.
    Do you have any advice how to prevent the smearing of glazing compound and paint as well as how best/easier to clean up?
    Best regards,

    1. Catherine, make sure the texture side of the glass is on the interior of the window. That will make the glazing process and painting process much easier. It also keeps the glass cleaner since exterior dirt wont build up on the smooth side like it would the textured side.

  18. I am restoring old (1920s) windows and wondered if the channels should be painted. They have been covered by weatherstripping but have no paint under the strips. The channel wood is quite dry. Would BLO be an acceptable to apply to the channel to protect the wood?

  19. Hi Scott,
    I have recently decided to stain the interior of my windows instead of painting them. I am wondering about staining vs. painting the jambs. It seems logical to stain them, but then if I paint the outsides of the windows, there will be a portion of the stained jamb showing on the exterior. Is this normal or should I paint the portion of the jamb that will be showing? I love all of the information in your window book. It’s been a great help to me.
    ~ Janet

    1. Janet, glad you found the book helpful! I typically stain only the portions that are visible inside the house and paint the portions visible from the exterior when the windows are in the closed position. Hope that helps!

  20. Hi Scott, Any knowledge about staing windows instead of painting them? Mis it feasible/advisable? Also, on the question of oil-based primer and latex paint… I always thought that it was necessary to be careful to not paint latex on top of oil base and vice-versa. It prevents proper adhesion and can lead to bubbles and peeling.

    I saw a Martha Stewart video on painting windows where she said a professional painter told her to use high gloss primer under all trim paint and to sand the primer a little before painting.

    1. Suzette, staining and varnishing Windows is definitely feasible and often done depending on your personal tastes. As for oil and latex, oil primer can be used under any type of paint. It’s when you try to put oil paint on top of latex paint or latex paint on top of oil paint without priming first that you run into problems. And any primer should be low-gloss. I’ve never heard of a high gloss primer which would be counterintuitive even if Martha Stewart liked it. 😉

      1. Thank you for the clarification about oil and water based primers and paint. I never realized that you could paint any primer on top of any paint, or any paint on top of any primer. I guess the problem is with paint on paint. I have never painted without priming. I must admit, in the Martha Stewart video, she was painting the interior of the window sashes using a high gloss primer.

        What do you recommend for staining and varnishing the exterior of windows?

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