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


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

  1. 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?

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

  3. 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.

  4. 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!

  5. 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.

  6. 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?

  7. 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!!

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

  9. 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.

  10. 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??

  11. 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.

  12. 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

  13. 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.

  14. 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?

  15. 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!

  16. 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?

  17. Hi Scott,
    I love all of the great information on your site! Also, your Old Windows Made Easy book has been awesome… I have seven windows that I am restoring and have recently decided to stain/oil the inside instead of painting. I cannot find any information about what I should do to the window jambs, though. Should I stain the entire window jamb and parting beads? Will this look funny from the outside? The outsides of the windows will be painted white. Should I also paint or just prime the part of the jamb that will show outside? I’ve also considered just oiling the jambs and only staining/oiling the sashes and trim inside. I would appreciate your input! fyi – I am using Heritage Natural Finishes Concentrated Finishing Oil over the stain.

  18. Is it ok to paint the top of the inside (bottom)sash and the outside (top) Bottom since its exposed to weather?

    1. Rick, painting the tips and bottoms isn’t he end of the world either way, but several tests have shown that leaving the top of the top sash and bottom of the bottom sash helps the windows moisture levels within the optimal range.

  19. Hi Scott,
    Thank you for great information. I’m in the process of restoring my double hung wood sash windows and have been reading your web site as a bible :).
    I have a question about painting the window frame hope you can help. How do you advice the best way to paint window frame? Which parts should paint and what parts should I leave bare?

    1. Catherine, there are a lot of regional differences in how the jamb was painted. Down here in Florida I usually paint all parts except for the parting bead which I leave with only an oil-based primer. That seems to help keep the sash from sticking.

    1. I have used their system a little bit and am doing some testing down here in Florida before making any final decisions about whether it should become part of our offerings.

      1. I love this site, restoring windows has changed the way I think about a lot of stuff related to maintenance and how to do it sustainably. Two questions/comments:
        -would like to see articles about how to set up a shop, things like work tables suited for stripping and de-glazing. I see you use an easel for the painting? I find these things to often be a make or break element of restoration projects
        -I’m also eagerly waiting for advice on linseed paint! Have 26 double hung sashes that nee a new lease on life.
        many thanks!

  20. Referring to your item #3, using an oil based primer. I’ve spent the afternoon trying to find KILZ Complete here in Ventura, CA and it seems that hardware stores here and even Lowe’s and Home Depot don’t/can’t/won’t carry it. HD will ship it to me, but nothing in stores. All other KILZ products are readily available. I already have both KILZ Latex and KILZ Premium from other projects. Would either of these be sufficient, considering the difficulty I am having finding oil based primer? (All other reviews I have read of KILZ Complete haven’t been so favorable either) I really have no complaints using the water based Latex in the past…but this project, reconditioning 3 wooden windows on a south facing wall – harsh sun and elements and about 3 blocks from the beach, so occasionally salt air…I do plan on using the Sherwin-Williams as you recommended.

    1. Patrick, California Paints makes a good exterior oil-based primer too which should be available near you. Any exterior grade oil-based primer will do the trick. For wood windows stay away from latex primers.

      1. Scott,

        Thanks for your quick reply. Sadly, California Paints is in Northern California, about 8 hours driving from here, and California has insane smog laws barring shipment of oil based primers. One of the Home Depots nearby has KILZ Complete in Quart cans (obviously not enough). They cannot order Gallons because KILZ Complete cannot be shipped to California. Bottom line is, the laws have made it really hard to get/use oil-based primers in California. I could have a friend who is going to visit soon maybe bring it from out of state, but that is not a guaranteed. It appears that except for ‘remaining stock’ all that is available in California IS latex based primer.

        1. There are other local stores that still have Alkyd/Oil based primers, including Sherwin Williams, but of course, they are more expensive and I do not know their quality. KILZ ‘Original’ is still available, and is supposedly oil-based, but I do not know if it is comparable to KILZ ‘Complete’.

  21. I am just embarking on refinishing the windows on my 1919 Craftsman. I find your site spectacular ad invaluable; so much great reading and easy to understand, though I have a fairly easy grasp of these things which helps. I fully understand what you wrote about not painting certain surfaces of the sashes and why. My question is what should I do with the jambs? Paint or stain/sealer/lacquer? Should I only coat the area of the jamb that would be most often exposed to the elements? I like the bronze weatherstripping as well, but I don’t want to leave the wood untreated but I want it to be done accurately and properly…the window I started this project on did not have much paint in that area so dismantling the windows was a snap. Now I just happened to glance up and see an answer you gave on Feb 17, 2014…but if there is anything more you can add it is much appreciated.

  22. I recently restored one of my 2nd story windows and put high quality storm windows in. Oil based primer, 2 coats exterior paint outside, 2 costs interior paint inside overlapping glass 1/16″. I get condensation on the inside especially when blinds are closed. I have been faithfully wiping dry each morning. After only 1 month I am already seeing cracks in the paint on the inside bottom rail of the bottom sash. Ticks me off ’cause it was a lot of friggen work and I have more windows to do! Maybe I should replace the glass with dual pane. I don’t want to end up re-scraping and re-painting every two years!

    1. Dan, what part of the country do you live in? Do you notice condensation in other parts of the house? 1st story windows as well have condensation? A lot of this is house specific and it may take a professional inspection of the house to remedy the moisture issue.

  23. Paint vs Stain/Varnish/Lacquer…is this just personal preference, or is it advised to paint double hung windows? my 1923 craftsman has all natural wood windows and doors, but the only PAINTED windows in the house are the double hung? I didn’t know if this was previous owners idea, or is there some reason for this?

  24. i just want to clarify, you prime with oil primer, and it’s okay to paint over that with latex paint? I’ve always heard the oil primer would “reject” the acrylic latex, and not create a bond.

  25. Scott,
    I found your video about painting sashes very helpful. One question: the video covers the exterior (i.e. glazed) side. In particular, you emphasize (as other sources do) “lapping” a thin fillet of paint from the glazing onto the window glass, to provide a seal. Makes lots of sense for the exterior. How about the interior side? There’s no glazing, and certainly fewer issues of water pentration. Is it necessary or recommended to lap paint between the wood muntin and the glass. (I’m talking old-style single glaze sashes.) Or is it ok to scrape off any paint on the interior side of the glass back to the muntin?

    1. Noble, yes you should still lap the paint onto the glass ever so slightly on the interior. There is a small bed of glazing putty there and to protect the sash from condensation in the winter the paint should go onto the glass about 1/16″ or so.

  26. Well, I’ve just managed to get my 100-year old casement window open, but I can’t get it open enough to expose the horizontal piece on the top sash (the one just under the lock) in order to scrape, prime, and paint. It looks pretty bad–peeling and flaking,etc. What can I do? thanks!

  27. I recently bought a craftsman house built in 1908 that has all the original windows. so I have lots of glazing to do. I want to restore this house to its original beauty and was curious about staining the interior of the sash instead of painting. I can not seem to find any information on painting the the outside but not the inside.

    1. Josh, we do a lot of windows that are stained on the inside but painted on the exterior. If you are planning to fully restore the windows I recommend that instead of priming the glazing rabbets you either use shellac or Boiled Linseed Oil before glazing. That way you don’t get any primer runs onto the inside of the sash. Once it’s glazed you can prime the outside and stain and poly the inside. Also, use a spar urethane for the interior which will hold up to the UV and moisture better than regular polyurethane.

  28. I am redoing the wood storm windows for my 1923 Craftsman bungalow. I stripped the paint, removed 90% of the glaze but decided to hand off for the rest of the removal and the reglaze. They didn’t prime before they reglazed with DAP33 compound. I am sick. The company is a reputable glass dealer in town. What do I do? I already have paid out dearly for them to do the work. Thank you.

    1. Joan, though I don’t use DAP 33 I do know that the manufacturer requires wood sash to be primed with an oil-based primer prior to glazing. I would contact the company and have them redo the work correctly as per the manufacturer’s recommendations. They should have known how to properly apply the glazing putty if they took on the job.

      1. Thanks Scott. I had called them before contacting you but was told they have always done it this way and have never had a problem. I also contacted their competition and was told the same thing. They don’t prime or linseed oil because of the dry time. It is a minor part of the business for both of them. They will not redo them. Lesson learned. Don’t assume that because they are the “professionals” that they are going by the book.

  29. What are your thoughts on a push-out casement window? Should the sides, top, and bottom edges be painted or left bare? My originals were painted, but they were also damaged slightly by rot on the bottom corners.

    1. We usually prime and paint all sides of casement windows since that was typically the practice for decades. I’m still doing some testing to determine what is best, but for now I haven’t had many issues with this technique.

  30. Great turorial Scott. I am in the process of restoring a large bay window and have removed the center picture frame for reglazing. It is now stripped down to bare wood and I have a question about painting the interior-facing side. Should it be completely top coated prior to installing glass or will the putty that oozes out of the rabbited area interfere with the painted surface? I’d hate to wait 30 days for the interior side to dry before tackling the glass installation.

    1. You’ll wanna seat the glass and wait a few days till the putty is skinned over to paint the interior. Lap the paint onto the glass about 1/16″ on the inside as well as the outside to keep the putty from failing prematurely.

  31. Scott – great article – I am undertaking the task of redoing 1935 double hung windows & some perhaps 1960/70 wood ones on the top floor. I’m in a historic district but the house was vinyl sided before I bought it and the windows wrapped with vinyl/the old windows were left in except for a side porch window. I’ll have to paint these in place/not removing them but I am at a loss on a few things. It appears I should abandon my plan to use Zinsser 1-2-3 primer & instead use oil primer. Not cool. But I will do it if that is necessary/I am presently removing years of old glazing compound/botched paint jobs and repairing wood. There are storms on the windows as well that I have removed screen and glass wise but the alum frames aren’t coming off – in some cases, the siding overlaps them – sigh. My question is should I paint the windows (sashes) to match the horrid vinyl wrap around them or should I contrast slightly? Any help or thoughts appreciated. I wish I could afford to have this done but really don’t have the money at this time to have a pro do it & I can’t let the windows deteriorate any further. They seriously need reglazing and paint. Thank you!!

  32. I think folks need to hear how critical prepping the wood for repainting is to the renewed life of the window. If the old, dry paint is not completely removed, the new paint will not stick well and fail soon. Stripping paint with chemicals or steam drives moisture into the wood. It takes extra days to neutralize and dry this wet wood. Infrared heat Speedheater works by softening the paint with low heat so the paint scrapes off easily. The bare wood is ready immediately for priming and painting.

  33. How do you handle sash tracks that have been painted? Do you strip them to help with ease of raising/lowering? How about any other lubricants or waxes in the tracks? Thanks!

  34. Best thing I ever did for my 1926 windows was to get storm windows. Also these old windows if kept rot-free are MUCH superior and more economical to repair that so-called double-glazed windows. Double-glazed windows are horrifically expensive and have a 100% failure rate.

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