Question on paint and primer

There are probably as many opinions on painting as there are people making them :o).

If you are new to painting, I would recommend using a two part epoxy primer and a single stage synthetic or, preferably, acrylic enamel without hardener. No clears. Single stage paints do not require a clear coat for gloss. If it doesn't specifically say "basecoat" on it, it is a single stage paint.

Two stage paints consist of a basecoat of color plus a clear. The basecoat is a very thin and flat film that only provides the color. There is no gloss until the second stage clear coat is added. Most all automobiles have this two stage paint system on them nowadays. Clears can also be added on top of single stage paints for an increased "depth" effect. I have used clears on top of single stage paint because I think it makes decals look more like they are painted on...it tends to smooth the otherwise sharp edges of the decal and "blend" them into the surrounding paint.

There can be considerable disagreement on the safety aspect of using hardeners and clears. Both hardeners and clears have especially toxic chemicals in them that should not be used without special safety equipment, in my opinion. New painters are unlikely to have such equipment, which can be fairly expensive. I therefore hesitate to recommend using these materials without knowing available safety provisions, even though they are generally considered to provide a "better" and more durable paint film. Do searches on "isocyanates" and "hardeners" in this forum for specific discussions on this subject.

Rod

The second part (catalyst) of the epoxy primers that I am familiar with is not urethane based and does not contain isocyanates. Epoxy is the only case that I know of where that is true.

PPG's DPLF epoxy primer is the higher-end product in PPG's line. It uses either DP401LF or DP402LF as the second component catalyst. PPG's OMNI MP170 epoxy primer is the economy product in PPG's line. It uses MP175 as the second component catalyst. The MSDS for this product is available at the link below. The MSDS for the others are also available at the PPG website.

You can see in the MSDS that the recommendations for respiratory protection is EITHER an air purifying (cartridge type) OR a supplied-air respirator. If you check out the PPG MSDS for a topcoat or clearcoat hardener, including a hardener for the "2K" primer surfacers, that will not be the case. In those instances, isocyanates are involved and ONLY the supplied-air is recommended specifically in the MSDS.

I don't know about the DuPont products. In the past they have been pushing the etch primers rather than epoxy but I see they now have an epoxy one. I forget the designation and I haven't checked out the associated MSDS but I would not expect it to contain isos.

If you (or anyone) know of any two part epoxy primers out there that DO contain isos, please advise. I certainly don't want to mislead anybody on this important safety point.

Rod

• MP175 MSDS