Replacing View-Master Windows

Missing or warped windows are a common issue with aging view-masters. Fortunately these are easy to replace with the right tools and instructions.

If you need help dissembling certain models view these links.
Model G Plastic 1959-1977
Model C Bakelite 1946-1955

Not only are these windows warped but they're covered in dirt. After removing the windows I rinsed them in soapy warm water and gave a final coat of Novus polish. They looked better afterwards but the warping was not fixed.

I'm still searching for the perfect window replacement material. The original plastic was frosted and diffused and most commonly found plastics are crystal clear. In the meantime I will compromise until a better solution is discovered.  If you have any ideas please share!  

Trace and Cut

Currently I'm using plastic from "top loaders" these are low cost trading card protectors found in hobby shops. Nearly all top loaders are made from archival plastic, which is a big plus. One top loader can repair 3 viewfinders.

Since the replacement is not frosted I prefer using the new and original parts simultaneously. The thickness change is less than 1mm and doesn't affect the Model G View-Masters. On the Bakelite Model C only one panel can be placed in the holder.

Original window laid first then followed by the new piece.

I hope that you have found this tutorial useful and informative. Please feel free to leave your comments and opinions below.


  1. I've taken the idea of using top loaders to cut replacement windows from and improved on it.
    If you use the 5 X 7 size top loaders, they are the thickness is that is very close to to the originals.
    Before cutting the top loader, sand both sides with some wet 800 grit sandpaper being careful to use circular motion. Once the loader is completely opaque, go over it again on both sides with some wet 1500 grit sandpaper. This will bring the surfaces to a smooth frosty texture. Keep checking by holding to the light until the entire loader is evenly sanded over the entire area. Once you are satisfied with the results, cut the new windows to the proper size. Install sanded side in and shiny side out. Keep the original windows aside for posterity; don't put them back in. They will only discolor the image because they have usually yellowed. The new ones will be crystal clear and provide truer colors, especially if using an LED bulb in a back lit viewer..
    I have also had success flattening warped windows by sandwiching them in parchment paper, then laying them under a warm (not hot) clothes iron for a few minutes.

  2. Heat gun on low flattened out the plastic lenses enough to get them back in. They were poked in sometime or left in the sun. As the light heat hits them, watch them very closely and keep the heat gun moving and they will flatten down. soon as they move a tiny bit back off the heat. turning over and repeat for any up turned corners. Imagine this would work with hairdryer too. point air directly down so they dont blow away. May not end up perfectly flat but this worked on severe case of warp.

  3. Hi I had a couple of badly warped back pieces on my recent purchase viewmaster C model . I solved that by taking them out placing in a saucer of boiling water for a couple of mins then taking them out and quickly pressing on them.I repeated this a couple of times and got an almost flat finish. happy with the result.

    1. Cool Tip. That preserves the original windows as well. I will try that in the future. Thanks for stopping by.

    2. Shops that sell survey and drafting supplies have sheets of "drafting vellum". These are sheets and rolls of plastic that is frosted on one side. They can be drawn on for drafting prints but I found they also make great Viewmaster lenses.

    3. awesome, is it the same thickness?


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