phosphoric acid Undercoat?

[Arthurdaily]

If sparaying a whole car, should you use a rust preventitive UNDER the self etch primer...? A lot of web sites say yes, and indeed the 'vactan' rust preventitive bottle I have says it can be used as a self etching rust inhibiting primer... but it does seem to leave a skin that peels off... not good for overcoating surely?

I suppose self etch, primer and the top coats should be enough to keep the water, thus rust, at bay!!!

[Dean]

Do you have a link to a website where this stuff can be bought? I used "Metal Ready" from Frosts, this you spray on, let it dry, then wash off the remaining residue. This leaves an etched surface to prime.

If you can link to the product, it might shed some light on what we think you should do.

[Dean]

http://www.paco-systems.co.uk/vactan.html

Is it this one? If so, once dry and cured yes over coat with primer. I guess that film is the "sealer" to prevent water penetration.

[Arthurdaily]

Yes, that's it Dean - but I have also found this stuff on ebay, just as good maybe??

http://www.ebay.co.uk/itm/42-STRONG-PHO ... 3a66d981dd

[bmcecosse]

Just a wash over with phosphoric acid based stuff will do - not great thick layers of the stuff. Even Coke might be good enough...it's loaded with phosphoric acid.....

[MarkyB]

And sugar!
You'd have to rinse it off methinks!

[bmcecosse]

Well yes -it was a slightly tongue in cheek comment.......

[MarkyB]

Maybe we need a tongue in cheek smiley?
One can't always tell.

[dp]

Always been slightly perturbed about putting an acid on to remove rust then washing it off with water. I guess you remove more rust than can appear before painting.

[MarkyB]

Seems like a poor idea to me too, water would find it's way into every seam and take ages to dry.
Paint it too soon and you would just seal it in