Do I have to Sand In Between Coats?

KCTractors · Nov 3, 2012

I am new to spraying paint. I just sprayed a couple of wheel centers with CNH paint(gray). The centers were painted red and red bled thru the gray, so I,ll have to give them a second coat. I believe it says to recoat within 24 hours, so do I sand the first coat or will the second coat adhere to the first coat with out sanding. It's just a work tractor.

Stephen Newell · Nov 4, 2012

If you are within the recoat window and the first coat is smooth enough then you don't have to sand it. The 24 hours is in regards to the solvents in the paint. After 24 hours the toluene and perhaps acetone in the paint will lift the first coat wrinkling it up like you put paint and varnish remover on it. If you are close to the recoat window I would test the paint in an inconspicuous place first. You may need to let the first coat cure for a couple of weeks before proceeding. Personally I like to wet sand with 400x between coats because there is usually some dust or debris in the paint you missed.

CNKS · Nov 4, 2012

If the centers are cast you can't sand it. You are supposed to apply coats about 10-15 minutes apart. If the wheels are steel, I would sand it off and use 2 coats of epoxy primer. An expert can get by with one, which I am not. If you insist on using the CNH primer, follow the instructions that CNH gives, and if you are outside the window, sand it good first. You do not sand any available paint between coats except acrylic lacquer which I don't recommend to anyone.

CNKS · Nov 4, 2012

I should have said that you can sand primer if it is designed to be sandable, some are not -- I was referring to topcoats above. However I would not sand primer after every coat, I would treat it like I do a surfacer which is used to give a smooth surface, in which case I put on 3 coats then sand, then put on 3 more coats if necessary and sand again. True epoxy primer is not really sandable except for removing a small mistake if you are lucky. The best treatment for sheet metal is epoxy primer followed by sandable surfacer -- surfacer will go on rough but that is ok because it is supposed to be sanded. In any case you do not do only one coat and then wait, they are all put on within a few minutes, 5-15 minutes unless it is very cold.

Jason S. · Nov 5, 2012

If you are close to the recoat window and are worried about the adhesion spray some adhesion promoter on it before you start spraying again.Ive used bulldog brand many times with great success. Its made for spraying into door jambs and other places where you cant sand and its also makes paint stick to urethane bumpers.

Do I have to Sand In Between Coats?

KCTractors

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Stephen Newell

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CNKS

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CNKS

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Jason S.

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