View Full Version : reacting primer

31-01-11, 05:33 PM
hi all i am currently doing up a kingswood ute as well as a paj but at the moment my kingswood is getting the paint, i have sprayed one side with matt black etch primer and some parts of it is reacting with the paint underneath does anyone know what would cause this? i thought etch primer was ment to stop paint reacting??? thinking about just paying someone to do this job

01-02-11, 11:46 AM
haven't done any of this in a long time but my experience was etch primer was only for bare metal and was generally a pale yelow sort of color but could be any colour. The matt black sounds like what we use to call GMH black which was for inside boots and chassis bits etc. It was a low quality paint, it wasn't acrylic not sure what it was.

01-02-11, 03:23 PM
Sounds like it may have been touched up with enamal at some stage??

When you say reacting what is it actually doing??- is the area you have painted going all wrinkly looking ?? or is the paint seperating and leaving lines of the under coulor like spider veins??

I'd like a little more info on this one before sticking my neck out on this one.

Is this going to be your final color or are you just preping for painting and this is your primer??

01-02-11, 05:59 PM
its going all wrinkly looking, i think it was 2 pac originally but im going to paint it with acrylic, the matt black is just etch primer, its only certain areas thats doing it not the whole lot

01-02-11, 07:17 PM
Did you wipe down the area down with prep wash or thinners before painting?

01-02-11, 07:29 PM
A very quick google.
Super etch primer is designed for excellent adhesion to bare metals. It may adversely effect some paint films when it is applied over them eg. some enamels.
Take care when doing touch ups, spot repairs or repaints. Suitable over automotive acrylics, N.C. lacquers, 2 pack epoxy, 2 pack automotive acrylic-urethanes. Not suitable over QD Enamel or Auto Enamel. Do not use under Polyester Spray Putty or polyester body filler. If in doubt test on a small inconspicuous area.

I've only ever used etch primer on bare metal, over paint I would use a normal primer or primer filler. From google sounds like you may have enamel underneath, pretty sure 2 pak is hard and non reactive to just about anything

01-02-11, 08:04 PM
so i can use just normal primer/primer filler instead of etch primer over enamel or 2 pac then paint over with acrylic?

01-02-11, 08:34 PM
As I said before I'm no expert but have sprayed plenty of cars in acrylic, if acrylic is going on top I'd use acrylic primer and only use an etch primer on bare metal, any paint should be sanded with 400 or 600 then wiped with prepsol or equivilent before the primer, then sand the primer with 600 or 800 more prepsol and acrylic paint straight on top

02-02-11, 02:54 PM
Yeah the boys are right etch primer is really only use for bare steel and alloy- it has a high content of acid to bite into the surface to give it adhesion.

You sould just be using normal Acylic primer.

Remember you dont need to pime over the whole vehicle if the paint work is in good condition you just rub it with 800 and paint over it.

You really only need primer where you have gone through to bare steel.

Now back to the original problem.

It to me sounds like with out looking at it a reaction to having your paint thinned to much.

When mixing your primer it should have a little fill to it for scratches and pin holes- rerub the area and get your primer to be as thick as say somewhere between full cream milk and thickened cream ( If that makes any sence).

If it paints real dry looking either thin your paint slightly or you can turn up your pressure more.

Its a real fine line between having it just right, to thin or to thick.

I would say you may have had your primer to thin and the thinner content in it reacted with what ever was already there.

Hope this helps cheers damo.

02-02-11, 06:11 PM
ok so sounds like it was the wrong primer and 2 thin, will have another go at it this weekend if i get my paj going again thanks every one will let yous know how it went