[VAC] Re: Polishing - .05 inches of Alclad ?

["Robert / Susan Harper" <rharper@xxxxxxxxxx>]

I spoke to Mike at Midwest Aero Restorations (IL) last week (discussing
polishing) and we talked about the Alclad. He says it IS usually clad on
both sides.  I suspected mine was since I had flipped one panel over and it
shined up nicely.

This may have to do with keeping the panel balanced, much like with plywood
and veneering. Generally speaking, if you want a balanced panel, you treat
it equally (inside and out, or top and bottom) to avoid different rates of
expansion and contraction (or moisture change) which could result in
warping. Maybe the science of cladding works the same way.

Mike says he's been polishing some 2024-skinned planes which were NOT
Alclad, and that they're coming up to a mirror shine, too.  He mentioned
something about a zinc-chromate treatment on the inside (yellowish tinge),
so I guess they're counting on waxes, sealers and regular maintenance to
protect the outside.

Bob

62GT/SC