Sorry to say this but, most of us have realized over the years and trees, that a properly made cut (at either the right time of year--or--with the right tool--or--in the right way), doesn't need anything but little dirt rubbed in it. If even that.
A healthy tree will compartmentalize on it's own and the healing process will begin right away. I've seen more damage done to a cut when using any form of 'cut-paste' than by doing any of the above things.
(don't know about Prep H tho, still thinking (and chuckling) about that one)
I admit to using the putty type stuff on azaleas though (they have a very thin bark). I think it helps prevent dieback in very thin-barked trees. Azaleas have a tendency to withrdraw sap lines sometimes after a cut and I think keeping the cambium moist untill it begins to callus naturally can help.