“I assume I should be able to tell the difference?”
You should be able to as watercolors look a lot different then oils or acrylics.
Also watercolor paper buckles unless flattened under glass. And you will be able to tell the difference between a canvas which is stapled onto a board frame over just a paper type.
Now I don’t know if he did oils or acrylics also. Acrylics can be done on canvas or canvas board. Or if he put a protective coat of some kind over all his paintings.
“acrylics”
There’s a 3rd option?
“Or if he put a protective coat of some kind over all his paintings.”
Good grief!!
Here is little I know. All his paintings are on a board of sorts, stiff and will stay in a frame with just the clips that hold it into the frame. The paint looks thick, almost textured. I think that’s why my friends were touching it.
So I’m guessing oils? Is there any harm in having glass over Those? Some do and some don’t.
The only ones that look different are painted on a gold or silver background. The paint looks less “lumpy” but is thick enough to be seen over the metallic background.