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How To Restore Steel Windows

Historic Steel Window
Image Credit: Scott Sidler

Historic steel windows are all across America. They became popular in big cities to combat the fires that were so common around the turn of the 20th century. Then, from the 1930s until the 1950s, they were a popular choice in residential housing due to the decreasing availability of quality lumber.

Many steel windows sit and deteriorate across the country. While much attention has been paid to restoring traditional wood windows by preservationists, historic steel windows have fallen through the cracks. Well, that is something I would like to remedy here at The Craftsman.

We have put together a comprehensive guide to walk you through the process of how to restore steel windows. I’ll discuss the highlights here in this post to give you a primer on the subject.

If you really want to get down and detailed about working with historic steel windows, you should purchase and download my picture filled e-booklet. It is 12 pages of everything you’ll need to know about restoring steel windows. It includes:

  • Materials list
  • Detailed photos and breakdowns of each step showing exactly what and how to do it
  • How to get old hardware working again
  • Time tested techniques we use everyday

Pick up your copy right here!

The Craftsman’s Guide to Restoring Steel Windows


How To Restore Steel Windows


Putty removalHistoric steel windows are best restored in place, though with some effort, they can be removed from their opening and restored in a shop. The process is pretty straight forward and mostly focuses on removing the old glazing and paint down to bare metal before applying fresh coatings.

Step 1 Putty Removal

Old glazing putty on steel windows is often much harder than on historic wood windows. There is also a possibility that it contains asbestos so you should have it tested before large scale removal.

The best way we have found to remove the old putty is using an inexpensive wood chisel and hammer, but be careful of the spring clips that hold the glass in place. Once all the old putty is out, you’re ready for paint removal.

Step 2 Paint Removal

Scraping paint down to bare metal is essential here if you want your new paint to last. Use a ProScraper to remove any old paint. Once the paint is gone, sand the surface smooth and wipe all the sanding dust down with a damp cloth when you’re finished. Then, clean the glass as best you can before proceeding.

Step 3 Pre-treatment & Priming

Treat any rusted areas with a rust treatment like Ospho (this step is fairly complex and is described in more detail in the e-booklet). Then prime all the metal surfaces with a quality metal primer.


Step 4 Glazing

Glazing steel windowsOnce the primer is dry, you can proceed to putty glazing. You’ll need a putty designed for use on metal sashes like Sarco Dual-Glaze or DAP 1012. Press the putty into the glazing rabbets and finish the putty with a smooth bevel and clean 90 degree corners.

Follow the manufacturer’s recommendations for painting the putty. Some putty can be be painted right away, while others require a couple weeks to skin over before painting.

Step 5 Finish Paint

Top coat with a quality exterior paint. The paint should be lapped onto the glass about 1/16″ in order to seal the putty. You need to cut in a straight line with your paint brush and let the paint dry naturally in order to create a good seal. I recommend using an oil-based paint whenever painting a metal surface.

Complete all these steps (other than putty glazing) on the inside as well and your historic steel windows should be ready for another 50 years with only minimal maintenance other than regular paint jobs.

For a more in depth explanation of the process you should definitely pick up my e-book The Craftsman’s Guide: Restoring Steel Windows

Subscribe Now For Your FREE eBook!

80 thoughts on “How To Restore Steel Windows

  1. Correction: We’re considering restoring our *steel* casement windows in our 1940 home near Berkeley, California. Any recommendations for someone who could do this work in our area?

      1. Thanks, Scott. My main concern right now with our windows is how most effectively to remove the rust/paint layers from our frames on site.

        1. Hello, I had the same issue with my windows. The process I followed was to first take a pro scraper and scrape off as much of the paint as possible. It will eat through the blades a little quicker, but worked pretty well. Then I took an orbital sander and sanded the metal (especially the flat parts) with about an 80 grit sand paper. That really took off a lot of rust. Be careful not to hit the glass of the actual window as you’ll leave marks on the glass. Then I’d take a wire wheel on a drill and go over it. Again, being careful about the glass. I’d especially use the wire wheel on the nooks and crannies and places I couldn’t knowck off rust with the scraper or sander. Now there will still be a little bit of rust in the hard to reach places, but I think the main point is to knock off as much rust and all loose paint and really, as much paint as possible. Then if you’re painting it with a brush, go over it first with a rust inhibitor primer (I used rustoleum) that is specially made for metal. Or, you can spray a rust inhibitor paint primer that worked well for me. I got mine at Shermin Williams. I used the brush paint for the outer most part near the glazing (so I could paint over the glaze like it was a wood window) and then used the spray for everything else. My windows turned out very nice using this process and look brand new. I’d also wire wheeled the screens and sprayed them and they look new too. I saved the screens as they were a very nice thick aluminum and to save money. You could also probably just get them rescreened. Hope this helps.

  2. Hey Scott, we have restored an entire house of Lupton steels casement windows and the handles are really binding. Any thought on something we can use to help them operate better besides WD40? Thanks In advance!

      1. Sly, not specifically. There are two issues here: 1) if the sash are being forced out of square from built up paint and caulk then once it is removed they usually close tightly. 2) if the metal is truly bent which is rarer but still happens. In this case the only way I have found to successfully bend it back is by applying serious heat and serious force. The metal developed a memory over the decades and it won’t be easy to have a true bend fixed.

  3. I just bought a “flipped” MCM last year and learned that all the windows have deep steel sills as well as frames. ((I’ve had to get real creative with my window treatments since I can’t drill into them to hang blinds)) The big issue is the window in the master bathroom which also happens to be in the shower. The previous owner appears to have just painted over what was there with latex paint and now the paint is chipping and rust is coming through. I want to strip the paint off completely, treat the rust, and do a more waterproof seal on the entire thing, but my big concern is possibly damaging with band new subway tile installed around it. Do you have any recommendations for this project? Like should I avoid a chemical paint stripper entirely?

    1. I don’t know whether or not you should avoid chemical paint strippers near your new tile, but I do know that citrus-based strippers work well enough for stripping latex off metal, as that’s what I used on mine. As it’s gentler than the chemical stuff, it seems likely to be a much better way to go. Try a small spot somewhere hidden and all that first (especially on the grout), but I’ve yet to find anything that was damaged by the Citristrip that I used. And, since I accidentally got it all over my granite countertops with no damage (and didn’t notice for a couple hours) there is at least that much anecdotal evidence in its favor!

  4. I am coming from a perspective in which my home has 26 Finestra steel casement windows. Mine are the ones without the crank mechanism so you have to physically push ypur arm and body out of the structure to open. I find one of the biggest problems with them is the screens. Our house has Pella roll screens, many of them still work, however the ones that don’t there’s really no alternative to fixing them or finding a product that works in its replacement which is sad. If you have any suggestions it would be greatly appreciated.

      1. Deggingers’ Foundry was part of the NPS award of excellence for the Brown v. Board for the steel windows.

        Call Tim Degginger 785-580-9092 cell.

  5. I have an extended cape in Ocala FL with several large steel casement windows. Please advise of any persons in the Ocala area, central Florida that does such restorations and repairs to these windows. The home was built in 1943 and also has recycled clinker brick façade. I think is quite handsome in appearance.

    1. Robert, my company Austin Historical does steel restoration in Ocala. Feel free to give us a call at 407-406-1755 and we can get you an estimate on your windows and some guidance!

  6. Hey Scott,
    I am about to purchase your ebook for restoring a 1929 homes steel windows. Do you feel like that this is something that a generally handy person can tackle on their own? I am very handy and can usually do just about anything. We are about to restore this home with all original steel windows and I got Seekircher to price it and needless to say it was very expensive and nowhere near in our budget. I would like to try it myself with the help of your book, but just wanted your opinion. Thanks for this blog. It is a great resource.

    1. If you’re handy it’s definitely not out of your reach unless the windows are severely rusted and need welding in of new steel. The biggest obstacle is time because while it may not be complicated it does take a lot of work and time. If you have the time to do it then you can make it happen.

      1. Hey scott, one more question on these windows. We are glazing the glass and the putty is not glazing over after almost 2 weeks. How long does it typically take to begin hardening?

  7. I am looking for a San Diego company who may be able to repair and restore the metal casement divided light windows in my 1950s era home. Any recommendations for a San Diego based company or individual?

      1. A different Mitch here but I also live in Texas and have steel windows. Any you know of any companies near San Antonio?

  8. Dear Scott,

    I am posting a comment here since there is no contact information for your store for inquires.

    On February 2, 2017 at approximately 12:47 pm I ordered “The Craftsman’s
    Guide: Restoring Steel Windows” (eBook). I have not received a link to the
    book yet. I checked my credit card and the charge is posted to my

    Please advise on the next step(s) so I may receive my book. Thank you.

  9. We want to repair and/or update the metal casement windows in our 1930 church in Indianapolis. Can you recommend anyone in the area to do the work?

  10. Our 1953 Spanish colonial in Arizona has original steel windows, some crank out and I love them. I have stripped the interior metal of about 3 layers of paint. The original color seemed to be a charcoal teal that has mostly but not all come off. I would love to duplicate but I’m guessing it was a factory finish that I could never replicate. Is there a best interior paint to try? Or if I leave the bare metal is that okay? If bare do I need some kind of protectant? (I am a graphic designer and I care a lot about color and surfaces)

      1. Scott-thank you and your site is amazing. I know it will be my number one resource as I restore my old place- windows and doors. Besides getting your Steel Window Guide I’m uncertain about painting the interior steel. As there is no putty, do you keep paint off the glass? Or do you still want that 1/16th bit of paint to overlap onto glass because it might help with sealing or sound transmission or heat/cold? Thx again.

      1. Oh, ok. I saw in the description where the price for the e-booklet is 4.95, but when I clicked to purchase, it is $14. It through me off. So, the e-booklet is now $14?

  11. Hi, I have two antique 9.5 ft by 5 ft steel windows from france which need to be restored. I live in Baton Rouge Louisiana and am looking for someone that could restore them . Would you please have any suggestions? I can send photos. Thanks, Luci

  12. I am looking for information on completely restoring salvaged antique steel frame windows. We are planning a kitchen renovation on our 16th century PA farmhouse and plan to use these windows. We currently have a mason working inside of the house to remove some walls and expose stone but are going to need to have the holes cut for windows very soon. We have not had much luck in finding any carpenters willing or interested in installing these windows. I purchased your book on doing the work myself, but it’s more extensive than what we’ll be able to do to 3 huge windows with our 4 children under foot! Can you point me to any experts in my area? We live in Chester County PA.

    1. Scott, thank you for your reply. We have found a solution for restoring the windows and are now just in need of some information on building the jambs into a stone wall and then installing them. My husband will likely be doing the installation as we cannot find any carpenters confident or willing to do it for us.
      Are there any resources you know of on building new window jambs for steel windows in stone openings? Specifically we need to know how much of a margin should be left in the openings to accommodate a (correctly built) jamb? This information is especially important for us to find quickly as our mason will be ready to begin work on the window openings within days from now.
      Thanks! Jill

  13. My detached 2-story garage has steel windows (luckily, only on the first floor) that are crying out for restoration: broken panes, thick gloppy cracked & peeling paint, and crumbling glazing compound. Oh, and lots and lots of rust. My home is c1830, with (known) major renovations done in the 1920s, 1960s, and 1980s, but I’m pretty sure the garage’s first floor came from the 1960s reno.

    The remaining glazing compound is, not surprisingly, rock hard and cement-like. If I had a few years, I could probably chip it all out, but what I’d love to do (at least on the panes that don’t need replacement) is to merely patch what’s there. Is this a horrible idea, or can I get reasonable results by patching?

    I plan to use UGL Glazol Glazing Compound, which I chose instead of the DAP because it can be used during a much wider range of temperatures (waiting until we have 2 weeks of above 50F weather so the DAP can cure properly is not a practical plan in Vermont). I’m sure this is not what was used originally; will using this slightly different formulation affect whether or not the patching idea will work?

    1. I have used Glazol and I believe as with most glazing putties it should perform fine when being laid in with some old putty. Make sure you remove enough loose putty and that there isn’t any dust in the areas you intend to patch.

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