I need some ideas for doing this. Non-abrasive, so the fine sand
add-ins for floor paint are out. And I don't want anything as ugly as
the pine tar used on a baseball bat, but more in that line.

I have wooden bench dogs that insist on falling down in their holes.
They are (freshly) finished with tung oil. I imagine that as the oil
dries out, they will lose some of their slipperiness. And I could also
put a little wedge under the "spring" (a sliver of wood on the side
that springs out against the side of the dog hole) to shorten and
stiffen it. But is there something else I could put on the dog's body
or the dog hole sides to make their mating less slippery? (Keep it
clean, guys!)

Wood is SYP if that affects your answer.
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