Quick question for the plastering gurus:

I've got some walls which I went at last weekend, pulling down anything
that was loose and crumbly. In some spots, this took me down to the
lath, but in large portions, the brown coat is still quite solid (and
well-affixed to the lath), and only the skimcoat came free. I'll be
filling in the big holes with structolite and then skim coating. But
I'm not sure what to do about the spots where there is still solid
browncoat.

I've seen some instructions to wet the lighty wet the old brown coat
and then skimcoat over it, but I'm wondering if putting plaster bonder
(PVA compound) over the browncoat would be better still. After all,
the last skimcoat didn't "take" very well.

Any thoughts?