Re: Priming and Painting over Existing Paint?
Paint applied to wood siding has everything working against it: A dead organic substrate that is prone to water absorption and decay, moisture from inside and out, and the effects of sunlight, temperature changes on two cycles (day/night and seasonal). Then, the paint's own chemical makeup works against it as it ages.
Old oil paint eventually loses flexibility through all these aging factors and cracks away from the substrate. That's alligatoring.
Peeling is almost always a signal of improper application or a moisture problem.
By improper application, I mean painting while the siding is damp, failure to allow the primer to dry, or a primer/substrate adhesion fault from inadequate prep (dirt, failure to sand).
Occasionally there is an incompatibility from primer to substrate or primer to finish paint.
Moisture problems include any kind of leak/other source resulting in wet water or vapor wetting the underside of the siding. The moisture moving through the siding causes the bond at the lowest layer to fail.
Remove not the ancient landmark, which your fathers have set.