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A choice must be made between the differing primer and paint systems available, i.e. basically between an air-dry cellulose type of repair, or the more durable but chemically dangerous 2-pack products. Each will be dealt with in turn, beginning with the first step - etch primer - which even some professional bodyshops choose to miss. Note:bad preparation cannot be cured by more coats of primer.
Etching Primer
Most commercially available acid based etch primers are supplied as primer base plus an acid activator which must be added before use. Some 1-component etch primers are available from motor factors and in aerosol form, which are not quite as effective as acid activated primers. Even so, the use of one of these is better than none at all. Whichever type is chosen, prepare the mixture per the makers instructions.
Depending on the type chosen, apply as follows;
Wash Primers, that is, with no filling properties at all, are usually applied as one single wet coat over all bare metal areas.
Etch Primer-Fillers have moderate filling properties and are applied in two or three wet coats, leaving 10 - 20 mins between coats to allow solvent to evaporate.
If etch primer is used under a conventional primer filler, then one single wet coat is sufficient .
The etch coat must be dry (resistant to a light fingernail scratch) before continuing with either primer filler or paint.
Please Note: Acid activated etch primer cannot be stored in metal containers once mixed. The acid component will eventually eat through tins, etc. The usable life span of the mixed product is limited anyway, so mix only as much as will be used at one time.>>>Continued
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