Vasa Warship Model has Brittle Windows

[ConservationStudent]

While cleaning the Vasa, I discovered that the cabin windows were very brittle, and cracked off with very little force. Any idea what they might be made from? Seemed like some kind of varnish, polymer, or glassy paint. It was applied directly to the wood underneath. I don't know how old the model is, unfortunately our museum didn't receive that information with the donation.

 

Thanks!

[druxey]

I would not want to speculate at a distance from a single photograph. As this is apparently a 'decorative model', I would simply leave things as they are with the lightest of cleaning.