whats the best brand of primer to use i heard of some kind of epoxy primer that act like gel coat. I have a few areas that need to be gel coated. I plan on doing the whole car woundering how much primer to and how many coats.
Thanks Al

 

There are a lot of very good manufacturers of primers, and they all have very similar product lines. But not all primers are intended for the same purpose, and they have different characteristics.

A lot of people refer to any primer product that is mixed with a catalyst as an "epoxy" primer. Be aware that this is not the case. Almost all modern primers are multi-component products with catalysts, but not neccessarily "epoxies."

"Epoxy" primers are "sealers." These products have excellent adhesion, and many are corrosion resistant. They will actually seal the surface, make it impervious to moisture, and prevent reaction of topcoats to the underlaying coatings. Epoxy primers are not high build, they do not fill imperfections, and are not easily sandable.

Urethane primers are typically "fill primers" or "surfacers." These are the primers used to fill imperfections and used as a sanding base to actually smooth and straighten the body panels. The urethanes are high build products, very stable, and sand easily. They can be topcoated with most paint products after final sanding, or they can be sealed using an epoxy sealer.

The Polyester products are the ones typically referred to as "gelcoat" type products. Polyester primers are very heavy build, and sand easily. They cannot be painted directly, and must be topcoated/sealed using a urethane primer or an epoxy sealer. The polyesters are thick enough to require use of a very big-tipped paint gun -preferrably a gravity feed gun. They do not spray well from a siphon feed gun.

PPG and Standox both make very good product lines in epoxy, urethane, and polyester.

 

I just painted the Moneypit. I used a high build surfacer by Sikkens. It was great to work with. The panels came out great, except for the two areas that I did not properly prep. I got in a hurry in two areas (its a driver, not an NCRS car so I don't care). The Sikkens high build primer flashes pretty quick, so you have to get it on the car once you mix it. After blocking the build primer, I went with the Sikkens Epoxy primer this is also a great product, but it does not block worth a flip. It seemed to gum paper pretty quick. The paper clogging may have been a product of high humidity, as I painted the car in Jackson Mississippi in early September (VERY STICKY AND HOT). I would recommend the Sikkens products, but the products Lars recommended are also very good. Do yourself a favor, and pick one brand, and stick with it. You may have some compatibility problems if you mix and match. The bad thing is these probs may not show up for months, and you may blame other causes.