stopping existing aluminium corrosion?

90 Rebuild saga

Having priced new panels for my tub, front wings and seatbox I'm going to repair my exiting panels.

The ally has corroded in the usual places complete with the usual holes.

Is it true that once corrosion has started it's unstoppable? I'm sure I read that somewhere, but find that unbeleivable. (i also read that a drop of mercury on aluminium will utterly shaft the stuff)

If I grind / sand back the corrosion to clean shiny alloy, spray on some etch primer, fix a primed aluminium patch behind the hole, then fill with wurth ally filler, sand smooth, re etch prime then some stonechip to the inner surface and a good dose of paint to the outer surface, should that stop it dead in its tracks?

If it won't do the trick, maybe I'm better getting the PRB panels (who's cheapest for them?)

Thanking advice in advance.

Sincerely,
A poor wretched filthy dusty oily cut lacerated rebuilder.

Make sure that the alli and steel and never allowed to come into direct contact with each other. This is what causes the worst of the corrosion; use a gasket between them.

yeah but what about steel bolts thru the ally...

i used plastic washers under the metal ones , a thick plastic bag will do.
to be fair though it took 22 years for my ally to corrode.

same again any gasket or locktite (lowest strength'll do) will do there is special stuff but I'll bet that's mucho expensive.