Self-Etching Primer CNKS / ROD and others

My question is I am going to brush this primer on the cast iron parts. I know CNKS and Rod you talked to me the other day about possiblities. The guy at the paint store asked if it was bare metal or partial bare metal. I told him that it was partial bare metal. There were spots where the paint didn't come off. He said that the self etiching would work better then expoy for something like that. He said to reduce it 1:1 if I was going to spray it on. He said that if I was just going to brush it on the cast iron parts I didn't have to reduce it. Is this true? Will it harden even without the #441-43 Activator Reducer.

Also, I told him I didn't want to use a hardener. I was concerned about ISO'S. He said that I didn't have to use a hardener with this paint. He said that my choices were alot slimmer since I didn't want to use hardner. My question is I have never used this Activator Reducer, is it harmful to you like ISO'S. Any special precautions? If I can get by with out using it I would rather do it. I don't really want to have to mix it up. Might mess up the paint.

Thanks,

I am going tomorrow to buy this. Now what paint in ppg would you recommend to use with the primer above? Please keep in mind the paint I want to use I don"t want any ISO"s in it. So no hardner.

What would be your suggestion? (Farmall Red)

I am going tomorrow to buy this. Now what paint in ppg would you recommend to use with the primer above? Please keep in mind the paint I want to use I don"t want any ISO"s in it. So no hardner.

What would be your suggestion? (Farmall Red)

Thanks,

LBH

Rod

I have never been a fan of etch primers. I used one once a long time ago but became convinced back then that epoxy was a better choice. So I probably am not a good one to address your questions. However, I will comment, based on what I see in the tech sheet and msds.

I really don't think that is a product to be brushed on. Etch primers usually are the consistency of water and are applied by spray with only a single coat. You do not want to use mulitple coats and want to maintain a low film build. The standard film thickness is typically 1/2 of what any normal film is. Since they contain an acid, usually some form of phosphoric acid, they generally are applied to bare metal only although I see that the tech sheet indicates a featheredged old paint is satisfactory.

The tech sheet says you must use the activator-reducer with the base product. So your paint guy is all wet on that one. Neither the base product msds or the activator-reducer msds indicates the presence of any isocyanates. The activator-reducer is said to contain phosphoric acid which is understandable, even expected. None of the constituents are good to breathe, as is the case for just about all paint products. However the level of risk does not appear to justify supplied-air and I think a regular canister mask would be satisfactory. That is also stated in the msds. If I had to trust anybody with these mattters, I would much rather trust DuPont and PPG than Valspar. If you followed the recent threads on that issue concerning Valspar, you know why.

Unlike the paint guy at your paint store, I'll most always come down on the side of epoxy over etch - but admit that is a personal preference and that etch primers are popular with many. The only things I would caution you about is not to use any other form of acid treatment (such as Picklex20, etc) either under or over the product. Don't use it over (or possibly even under) a plastic filler. You also need to think carefully about applying a topcoat directly to it. I have not seen a topcoat from anybody where an etch primer is recommended as an acceptable substrate. Usually it is recommended to apply either an epoxy primer or a surfacer over the etch primer before applying the topcoat. While they are called "primers", I think etch primers are considered more of a pretreatment for bare metal than an actual primer.

Personally, I am a little nervous about any etch primer on castings but I don't have a defensible reason for that. If you are definitely going to brush something on castings, it is not clear to me why you would choose an etch primer to begin with. You should be able to brush an epoxy on just as easily. Since you likely would need to apply something over the etch anyway before topcoat and a surfacer is not needed or recommended on cast, I see no advantage to you at all in going the etch route. NASON has an epoxy primer that I am sure would be just fine for direct application to cast. You'd have to verify that the activator for does not contain any isos, but it is very unlikely that it does. I have not seen an epoxy yet that has isos in the activator/catalyst.

Rod

I am brushing the castings? Several people around here do it and it looks good. I don't have a air compressor or a paint gun. I am going to get a friend to spray the sheet metal parts for me, when I go to visit him.

Primer?

I would probably prefer PPG paint? What is your best choice?

THanks for the help

Sorry to be so much trouble. just want to be safe.

Thanks,

LBH

Just want to make sure he didn't make a second typo. HA HA HA HA.

Thanks,

LBH

Just want to make sure he didn't make a second typo. HA HA HA HA.

Also do you have to use the MP 175 catalyst with the primer or can you use the primer with out?

Sorry to be so much trouble.

THanks,

LBH

You don't have to apologize for anything. Any responses you get here are opinionated and entirely voluntary. To answer your latest up above: MP 170 and MAE w/o hardener tech sheets.

The paint store does not add any hardener. The isos are in the hardener, not the basic paint. If you are going to use it, you mix the hardener in yourself just before you are going to use it at the same time you add the reducer. Once the two parts (paint+hardener) are mixed together, there is what is called a "pot life" of typically a few hours, after which the mixed product is not usable. If the paint store mixed in the hardener, the stuff would turn to jello right in the can after a while and not be usable. Yes, you have to use the MP175 catalyst with the 170 or the stuff will not cure properly. PPG has recently added a 15 minute induction period for the 170. See the tech sheet. That means that you mix the 170 with the 175 at least 15 minutes before you spray it. Stir it well and periodically during those 15 minutes and just before you put it in your gun - or in your case, before you brush-apply it. Make sure you print out those tech sheets and keep them handy.

Some suggestions on the MAE. That stuff is intended to be applied by spray. It dries reasonably fast. It will appear fairly runny to you after mixing with any reducer. I think you should brush lightly to avoid runs and plan on applying at least three separate coats, about 15-20 min apart (I'd arbitrarily extend the normal 5-10 mintues to 15-20 for brushing). You will want to tackle smaller areas and not a whole chassis at once. Break it up into manageable sections. If you don't, you may have trouble keeping a wet edge when you get back to the point where you started. You want to keep a wet edge to avoid obvious lines of demarcation and brush strokes. While you may have already purchased a reducer, if I were to apply it with a brush, I think I would opt for a slower-than-normal reducer, like the MR187 or 188 - that would assist in slowing down the drying and help in minimizing brush strokes. Take this with a grain of salt because I've never brush-applied MAE.

Rod

Also do you have to use the MP 175 catalyst with the primer or can you use the primer with out?

Sorry to be so much trouble.

THanks,

LBH