what kind of primer to use?

Anonymous-0 · Mar 19, 2012

i have painted alot of my own tractors but now i am doing it for other people i was using alot of oil base or synthectic enamel primer on the chassis and a high prime laquer sandable primer on the sheetmetal but the dry time on the oilbase is terrible and if i try to paint before its try the paint just fish eyes recently i talked to auto parts store and they recommended an epoxy primer and urethane on the sheetmetal but i don't want to have 350.00 just in primer any ideas? maybe an arcrylic enamel primer on chassis and laquer high build on sheetmetal? thanks

Rod (NH) · Mar 19, 2012

A two part epoxy is the best choice, even under a lacquer-based surfacer. Before you give up on the idea of epoxy because of anticipated high cost, check out the cost of PPG's OMNI MP 170 epoxy primer at a PPG jobber. You might find it to be acceptable. It is fast drying but does have a maximum time window of 3 days to cover with a surfacer or direct topcoat in order to avoid scuffing and reapplication.

CNKS · Mar 19, 2012

You can topcoat or put surfacer on Omni MP 170 epoxy in 30 minutes, I haven't bought any in a while, but it is no where near $350.

JRSutton · Mar 20, 2012

Sorry to jump in here - and I know the topic of primer has been disscussed a lot here - and seems like epoxy is the way to go - but I'm still not clear on exactly what the benefits of epoxy primer are.

Is it a matter of durability? Does that even matter since it's under the top coat?

Not trying to debate the issue, I just have no clue.

Rod (NH) · Mar 20, 2012

Better adhesion to bare metal than any other primer. Better moisture resistance - it's literally waterproof. Years ago I sandblasted and primed two coats of epoxy on a hood cowling on a Honda Accord. I never got around to topcoating it before I got rid of the car. But it was always outside in the rain and snow for several years with only the primer. There was no indication of any rust forming under the primer or any failure whatsoever, except fading of the gray-green primer color.

Does it make a difference since it's under a topcoat? It does from an adhesion standpoint. I don't know about the moisture issue. I suppose it depends on the topcoat and the relative moisture permeabilities. Certainly if a scratch was only down to the primer, the epoxy film would provide better moisture protection to the bare metal than any other primer in the same situation. It's the only bare metal primer I've used for the last 40 years. That's how good I think it is. Others will have their preference but for me epoxy is the only way to go.

kencombs · Mar 20, 2012

My preference is Kirker Epoxy. Cheaper than most epoxies, easy mixing (50/50), no induction time (just mix and spray, no wait), and it can be sanded fairly well. Most epoxies don't sand well. It sticks to metal like glue, well it is an expoxy, right.

Let it flash for 15-30 minutes and spray a sandable primer on rough sheetmetal, or right to your finish coat if the metal is smooth.

JRSutton · Mar 20, 2012

You sold me - just the waterproof-ness could be valuable. Like you say, with a little light scratch of the top coat, I'd imagine having a waterproof primer coat is a very good thing.

Might not help in all cases, but certainly some.

Thanks

Stephen Newell · Mar 20, 2012

Epoxy primers provide a better moisture barrier and they are also chemical resistant. Being chemical resistant is especially a plus for tractors since more oils get on the paint than does a car. Some other types of primers are porous enough they allow water to get under your paint and rust the metal under the paint especially if there is nick somewhere. Then since epoxy is so common on automotive finishes, most automotive finishes are tailored to go over epoxy primer.

Jason(Ma) · Mar 22, 2012

another way to look at things is to check out some of these comerical direct to metal paints. I'm currently thinking about trying some ppg AUE-370 tech sheet cpcpb226. I dont know very much about this product I've seen the results of a similar dupont product. This ppg one is only available at a platinum level dealer.

CNKS · Mar 22, 2012

Too much info for me to digest and figure out. I doubt if it has the gloss of automotive urethane, but some purists don't want the gloss, anyway. You will also have the problem of rust if it gets chipped. On sheet metal you are going to use primer and surfacer anyway to get a smooth finish. A quick scan indicates that the surface had better be sandblasted or some other method to insure adhesion, which makes me think there may be a question of how good it adheres to the metal. And epoxy is the easiest primer to use that exists. No reason to omit it except for a few minutes time, and of course the cost. Only my opinion without studying the stuff in detail. I'm not saying it won't work, but I don't want to take the time to see, I like what I am doing now.

what kind of primer to use?

Anonymous-0

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