Shellac for Sealing Foam?

What is Shellac?  Shellac is a fast drying transparent finish that is mostly used to seal wood, but can also be used on other surfaces.  It can be used as an undercoat or as a top coat. Shellac is a natural substance (made from bugs or something) and has been around forever.

Is it a good undercoating for foam?  Here is my experiment:


I used a spray can product called: Zinsser Bulls Eye Shellac and sprayed scrap pieces of foam with 1-4 coats of Shellac. Then I topped the shellac with one coat of metallic spray paint.

You can see my results above.   The result wasn’t a smooth finish, but the finish wasn’t bad if you wanted a mated or grainy type finish – like if you were making imitation stone.



Here is a picture of the 4 coat foam after  being flexed and you can see where Shellac fell short.  Flexing created a lot of tiny little cracks across the entire surface.

Conclusion:  While shellac might be a great way to seal that wooden airplane model and I liked that it was non-toxic and “natural”, I don’t think it’s a good choice for foam because of the cracking. I assume cracking would be a problem when used as both a top or bottom coat.    And at $7.50 a can,  there are a lot of other options which are a better choice.


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