primer help

My suggestion would be an epoxy primer. PPG has two of them. One is high-end and relatively expensive (DPLF) and the other is the more economical (OMNI MP 170). Both are non-sanding primers, which means that they are not intended to fill imperfections and be later sanded smooth for the finish coat. If you have glass-smooth metal, you do not have to sand and can usually go direct to your topcoat after the epoxy. If you have imperfections such as sandscratches, grinding marks, etc., you would want to follow the epoxy with a primer-surfacer of some sort prior to the finish color coat. You would then sand the primer-surfacer smooth, say with 400 grit, and proceed to topcoat. Primer-surfacers sand easily. Epoxies do not.

Epoxy makes an excellent primer IMO. I have had sheet steel with two coats of DP (predecessor of DPLF - the LF signifies lead free) on a car always outside for several years without topcoat and no hint of rust showing through. If you are not going to topcoat right away, I don't think you can beat the epoxy for preserving the metal.

The only downside to epoxy is that it has a recommended time window within which you should topcoat. This is usually between one hour and one week, depending on brand. The OMNI MP 170 has a three day window. If you miss this window, you would need to scuff-sand and re-apply the epoxy prior to putting on the color coat (this time within the window).

Both the above epoxies are two part products and need to mixed with a catalyst prior to use. The good thing is the catalyst does NOT contain isocyanates and a regular chemical cartridge respirator will provide adequate breathing protection.

Make sure you get ALL the rust out before priming with anything.

Check with local suppliers to autobody shops to see who carries PPG products.

Rod

thanks rod . you anwsered most of my questins .what i am after is a rattle can type primer to hold things until i get it done professionally . i don't want to put something on that's going cause a probem later on . i have some plasti- kote sandable lacquer primer a product of valspar co. will this be ok?

I am not a fan of rattle can anything although I admit they do have their place. I have no experience with the product you mention. I am sure it will provide some protection to the metal. How much so and for how long is an open question. I doubt it would be as good as an automotive epoxy though and I would try to keep it undercover as much as possible after using.

Another thing to consider is the topcoat to be used if you are going to have the job done professionally. There could be some compatibility problems, depending on the topcoat chemistry. You could try asking whoever you are going to have do the final painting for their recommendation. A possibility would be for the rattle can primer to provide a temporary protection under cover but then be stripped and the material reprimed with a better product at the time of topcoating; preferably with a product that is recommended by the same manufacturer as the topcoat paint FOR that particular topcoat paint.

Rod