Hi All, got a new chassis I'm getting ready for primer.
Asking for any opinions on how to best prime it. Please name brands if you've used a product you've been happy with. The chassis will match the body when done. Epoxy, Urethane, Polyurethane ?? I'm so confused. Nothing new !! LOL
Thanks in advance.
Dean

 

It depends a littlebit on what you want and how you are planing on using it when done.

Primer are two main options.

Plain 2 component epoxy based primer that works a a physical barrer to prevent rust.

2 component epoxy based primer with a lot of zink additive that also works as a chemical rust preventing agent.

On top of that you have basically two choises, 2 component Polyurethan top coat or a 2 component epoxy based top coat.

Epoxy one will give you a harder and more shiny surface finish that is better for show use, not very good if you plan on traveling on dirt roads as it tends to chip a lot more due to beeing harder than the polyurethane.

Polyurethan opposit of the above, not as shiny and abit softer and protect agains stone chipping better.

 

primer needs to be compatible with your top coat. I prefer epoxy. If you topcoat it within the re-coat time window, you don't have to sand it.

 

Thanks guys. I'm leaning towards an epoxy primer to seal it up good. This is going to be a high boy, so the frame and body color must match. So I would prefer to a 2k urethane over that because that would match the body primer. I'm assuming 2k urethane is a higher build primer which is easier to sand. Here the rub, I like the polyurethane chip resistance for the chassis. Hmmmmm

Won't be top coating for a while. Going to do a mock up of the whole thing in primer.

At least that's the plan. Thanks for the replies, Dean

 

I having been using Advantage 325 (325 High Build 2K Direct to Metal Primer - Gray 2.1 VOC - Advantage Refinish Products) with good success. It is a direct to metal primer that can be used as a high build all the way to a sealer depending on how much you thin it. Sands nice with no build up in the paper, either wet or dry, and great adhesion. I shoot House of Kolor paints, including the KD3000 series sealers, with no interaction between the primer and the sealer/paints. HOK is considered to be "hot" paint/reducer so this is a big deal for me.

 

Thanks Charlie, is it an epoxy primer ? l've heard good things about SPI, but is that a polyester ? Is polyester an epoxy based product ?
Thanks, the technology of paint is confusing. Any help is appreciated.

 

The term "epoxy" has become muddy in the past few years. It used to be that you had lacquer, then it was polyester (identified by the MEK hardener ala resin), then came "epoxy" which like the glue was more of a large ratio (not 1:1 like the glue however). Things generally evolved into what we have known as 2K primers...which can cover both polyester AND epoxy since they are both "2 part" products. The 2K primers that I use, and which comprise the largest market today, are an epoxy-based product that has been refined to tailor it to the automotive refinishing market. Back in the day, if you had a panel painted with epoxy primer, as was the case with many powder coating operations, the finish on the panel was so hard that it was very difficult to sand. It also had issues with cracking and adhesion in some cases. The 2K primers on the market today combine the best qualities of the "true" epoxies with the workability of the old lacquer primers. SEM Metallock and Advantage 325 are similar products, both are good examples of the state of the art in primers today. They mix and spray smoothly, high build to sealer consistency, they have excellent adhesion both to bare metal and existing finishes, they are inert when it comes to chemical interaction with most any brand of finish paints, and they will not allow parts to rust even when left un-topcoated for months. Hope this helps...