update .
It's not dope. It's paint of some kind.

Tried some clear dope with thinner. No reaction.
Tried straight dope thinner. No reaction.

Tried applying heat with a blower and managed to start to peel/melt the paint a little.
The paint job started with a grey primer. So I'm thinking it's either automotive paint or some other type of paint .

I think but am not sure the fabric covering might be silk. The heat didn't seem to hurt it. Although when I applied heat to a flat area with solid wood under it the fabric started to balloon up a little and had to press it back down.

Will aircraft type stripper harm the fabric or balsa? You have to wash off this type of stripper with lots of water