Painting the undersides of figures

I'd also skip thinning the underside of the mini.  It'll add a lot more work and if you have a bunch of them to do then it becomes a long process.  I usually leave it either black if I primed black or just the color of the outside.  I'm painting up a ton of 28mm wargame figures and their use is gaming so nobody really cares as long as it's not bare metal.  Display pieces would be another matter but I don't use 28s for those. 

retdfeuerwehr

This may sound dumb, but....oh well: I'm working on the outstanding Victrix 28mm Roman Imperial soldiers. What is the best way/color to paint the undersides of the figures...i.e., under the tunic? I was thinking of hollowing out that area a bit with a motor tool, then painting it - sounds like a lot of work that may or may not work. 

Not a dumb question at all, quite legitimate.

I don't paint figures that small; the smallest I paint are 1/72 scale.  But the concepts are the same.

I paint the undersides or insides of pieces of clothing as much as I can paint them in the same way as painting the outside, taking the sculpt and what can be seen into account.

For example, my old Stadden SYW officer figures were sculpted with their coat skirts solid, especially the back part.  I just paint the coat lining color on that surface. 

In the case of your Romans, if the underside of the tunic is sculpted, then I'd use a darkened shade of the color I used for the outside of the tunic, and darkened shades of flesh, for any exposed flesh.

If the figures are not sculpted in such a way that those details are molded, I'd leave them alone, and again, just use a darker shade of the tunic color for the underside.

Hope that helps!