I have some finished and/or lacquered HARDwood wooden bases and am wondering if I could lay plaster and groundwork straight on top of them. I read long ago that one should NOT do this to unfinished pine bases (such as the ones one could buy cheap in the Crafts stores) because over time, the water moisture from the plaster would bend and warp the base. The advice was to paint the pine base and lacquer it first or not even buy pine.

But would the same problem occur for hardwood bases, some with gloss finish coat? Do I need to glue on a piece of plastic to the base first to prevent water seepage or could I just lay on straight wet plaster and putty and build groundwork from there? Thanks!

Ola Peter

Well if the bases are laquered then you are probably ok with laying plaster directly on top of the base. However be carefull as plaster doesn't really grip well on smooth surfaces and it doesn't take much handling for it to come off. You can give the plaster something to bite into by scoring the base but that in turn exposes the wood to moisture risking the wood to split. And every dried wood starts to work again after it has been subjected to moist.
I always play on the save side and simply glue a piece of foam onto the base first and built up my groundworks on that.

You could try using Celluclay instead of plaster as it is lighter and less fragile, although it could still warp the base if the wood has not been varnished. It won't affect varnished bases but has the habit of sometimes warping off the base at the edges while drying. White glue in the Celluclay mix helps prevent this, but if it still does, stuff more mix in the gap when it's dry.

Thanks for the answers. That's true! I didn't think that the plaster would slip from the smooth base...thanks for that tip!

I think gluing on foam to the wood would help then. Or I could glue on a piece of plastic first.

I'm still looking for other ideas so if you have some, please keep them coming! Thanks!

Ola Peter

You can glue a piece of styrene on it first but you need to score that first before you add the plaster otherwise you will still have the smooth surface problem.

I always use styrofoam. It is easier to shape the top surface and because you only coat it with plaster or whatever you choose you also keep down the wait. Never have any warping and the sides of the foam I cover that with a border of styrofoam.