Turpenoid is a less aromatic and thinned down version of turpentine. Most artists use it as a wash with their paint to get different effects, ie- dip their brush in whilst it's already full of a color so that it turns out transparent and streaky.

It's really cool to do if you're painting a sky. You can take thalo blue and azurine onto a turpenoid loaded fan brush, spin it on your canvas, and without even adding white it looks like you have wispy ice clouds that you can just go back and highlight later.

So, yes, my point would be- that's why it made your paint and pencil markings blend together. It isn't really used to remove color so much as to make it more malleable.

I think your drum turned out fantastic. The colors are really vibrant and strong; it suits you.

Oils take a long time to dry though, especially in damp environments or if you put on a lot of layers. One of my more elaborate paintings can take a week to four weeks just to get to the point where it's safe to touch. It would be best to set the drum where it won't be disturbed and lay a tarp over it so dust can't get to it as it dries; just make sure that the fabric isn't actually touching the painted surface.

Also, you should think about buying a fabric safe sealant for afterward, to prevent the colors fading or flaking off. Just spray it on once the whole mess is dry, and it should prevent dirt from adhering to the surface of the canvas when you start playing it again.

BRAVO, on a job well done.

Sorry if I came across as a know-it-all.