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962porsche 962porsche is offline
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Join Date: Feb 2009
Location: branford ct
Posts: 3,437
Originally Posted by strath44 View Post
"primers do nothing to get adhesion " hmm yes and no they won't do anything to get adhesion if the metal / base is badly prepped or contaminated, but the one of the main purposes of a primer is to give an adhesion of which a colour coat doesn't contain the same properties!
primers are not made for gaining addhesion at all it's a surfacer to give you a flat even surface for the top coats to lay over the top of so they will not srink into the substraight . that is all a primer is for . it's in no way a adhesion promoter ! it will not add one bit to getting a top coat to stick any better .
that is why you only have to prime over a repair area and not a hole panel .
say your doing a repair on a door you prime the repair area and then spray your color over the repair area and walk the color out twice as far as the repair area was . then you clear the hole door . you in no way have to prime the hole door to have the top coats to stick to the door it's self .
now to get the top coats to bite into the primer and old substraight all you have to do is sand the hole door and every bit of it with the proper grit sand paper and panel prep scuff product like sem's # 38338 .
if you look at the photos you may see it does look like there is a primer or a sealer that could have been used ? in the rain channel it looks like it has a much darker color under were the top coat is pealing . also if you look around the wiper post you will see what it looks like a very thin gray line that also tell me there could be a primer or sealer that was used when the car was repainted .
the simple fact is if it's not sanded and sanded right with the proper grits of paper and scuff prep then nothing you put over the top will ever stick .

now the black under the top coat on the rain channel could have been a seam sealer that was not primed over that may should have been . and the top coat is just lifting off that because it needed a sealer or primer ?

Last edited by 962porsche; 05-10-2012 at 05:45 AM..
Old 05-10-2012, 05:39 AM
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