On 23 Aug 2012 11:53:52 GMT, "AL_n" wrote:

It's funny, but I've always thought etching
primer to be a con. I used to use it when I was doing a lot of refinishing
work in a certain factory in the 1980s. I found that after it was cured,
you could scratch it off as easily as most other paints and primers. OK, it
might roughen the surface of the steel very slightly, on a microscopic
level, but any abrasive paper does that far more effectively.

A number of car manufacturers, in conjunction with their preferred paint
supplier, specify the complete paint process for bodywork. Etching primers
figure in a lot of them - for instance all the vehicles with 'galvanised'
bodywork such as Porsche and Audi from the mid 90's required etching primers or
the subsequent layers fell off. If I recall correctly the only surface
preparation allowed was an extremely fine grade of Scotchbrite and a wipe on
wipe off solvent. Normal abrasive paper was off limits and panels were
completely replaced rather than part repaired.

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