ok so my OH has been today to "prune" the big old apple on my allotment, what should he paint on the stumps? :)
nothing. ;)
I don't like to prune apples when it's wet weather. Usually, as tonybloke says, it's not really necessary to put anything on the wounds, but if they're big, and if there're any fungal diseases in the area, a smear of vaseline won't hurt.
The use of things like Arbrex Seal are no longer recommended by the RHS, the current thinking is that they are no better at preventing a virus than nature itself. However plums and cherries may still benefit.
If you are going to use a wound seal, it needs to be applied immediately after cutting, so you might be too late anyway.
The problem with wound seal is that you can seal fungal spores in, and offer them a nice damp atmosphere to grow in.