Technical Difference in Primers

You can buy a varible speed buffer for less than $65, put a 8 in sanding pad on it, buy 8" 80 grit sandpaper and you can strip / sand the whole thing to bare metal in 1 day easy. Then epoxy. This is the tried and true method for a great foundation to build on top of.

 

Great stuff; this thread in and of itself is a reason to be an alliance member!

Wondering what you think of Bill Hirsch paint. I bought the metal prep, miracle paint, and chassis black. The metal prep just etches, so it must be phosperic acid. Then the miracle paint seems much like por, and the chassis black is the final.

I have stripped everything (this is just chassis, not body) but I am not in a shop per say, and things can get a little flash rust, so that is why I wanted to go with the miracle paint. Experience welcome.

 

I looked up the Mircle Paint. Its a moisture cure urethane, I have never seen that brand before, so I can't be much help.

 

So I went by my local paint shop today and they use PPG and recommended "shop line" JP37x epoxy primer. It's says on the product info sheet that "jp37x series primer must be scuffed and reapplied if allowed to stand more that 3 days." Does that mean it can stand for a long time after that without doing anything to it ? That's what I want so I can start mock up.
Then I went by a paint shop I had another car painted and asked about it, he said it was "crap" He says he uses Sherwin Williams products. Opinions ? Options ? Thanks, best paint thread. Much appreciated.

 

The 3 day period is probably the time allowed to top coat the epoxy without sanding. Just curious did they quote a price on that epoxy?

With the shop, he says its crap, but what is crap about it? Sandability, sprayability, adhesion. Usually its just a brand name issue and not a product issue. This industry is by far the most "brand" driven industry out there.
If you are doing the work yourself, you are doing great by checking local paint companies, getting on here and asking question etc, if some other shop is going to do it, let them get the material they want to use. Right wrong or indifferent if it screws up, its on them and they can't blame you.

As far as S/W products they make good stuff and economy stuff just like ppg, valspar, axalta, basf, Akzo and the list goes on and on. You have to make both regardless, that's just the way the industry has gone, unfortunately though a lot of paint companies could sell their premium products at the economy price but hey it would make life harder on me if they did.

 

Thanks for your reply. The price is $152.35 before taxes. That includes the hardener. The paint shop didn't say what was wrong with the JP37x, just that is a low end poor quality. I'm sure he just wanted to get me to use him to do it. The wants $550 or so to put two coats on. Seems like a lot. I had planned on doing it myself, but I thought, as you pointed out, that if someone else does it and there's problem it's his problem. BUT I have a feeling it will ultimatley become my problem if he screws up. Might be a PITA.
Do you think the quality and price of the JP37x is worth it ? Thanks again. This stuff is like second nature to you, but confusing as hell for me.
Dino

 

Hey Dino , I used PPG esu460 . Works great and was told by rep I could use all their other products . It has the 72 hour redcoats time or sand . Cost 74.75 for gal paint . 30.45 for harder . Still seams high but ? Been real happy with it ,used some bonds and filler primer on it . And it top coated real nice . I'm doing my project in stages and the epoxy does sand hard after a month . Blue

 

Thanks Blue, sounds like it's cheaper than what I was quoted. Things are expensive around here so close to D.C. I have no idea what the difference between the JP37x and esu460, but same company so probably similar. Once it sets up, how hard is it to sand ? What did you use after primer ? I'm thinking of using a 2k urethane primer over it because it's easier to sand. Am I making extra work for myself ?
Thanks
Dino

 

I too use a filler primer but it was right before I was ready to paint . The epoxy is hard but you can skuf it and coat . Use and sand with what ever you are putting on top suggestion . I epoxy end , 80 gritt where I needed bondo then went with180 over whole thing and used filler primer , then 350 and topped coated . Got some runs but that's because I couldn't see good enough , old and not enough light . But it cut and buffed great .
You can see it on next to last page in my tread . Blue

 

Thanks for the advice, Blue. I can use all the help I can get when it comes to painting.

 

What is the general consensus regarding DTM epoxy chassis paints such as this: http://m.summitracing.com/parts/sum-up500

 

If a primer that is 30% solids is $40 a gallon, and a primer thats 60% solids cost$75, the $75 primer is cheaper per mil of film build than the $40 primer. So don't look at price alone. Look at volume solids content and mix ratio and compare that at a gallon ready to spray. So let me explain mils, so lets say with each coat of primer you sprayed 3 mils on, if the primer is 50% solids, when the primer is completely dry, it dries down to 1.5 mils of build. So you put 3 coats of primer (9 mils wet) you would have a film thickness of 4.5 mils.

So example of mix ratio with 2 different primers with the same solids content:
Primer #1 - mix ratio is 4:1:1 which is 4 parts primer, 1 part activator and 1 part reducer. the primer cost is $50, activator is $25 and a quart of reducer is $20. Thats $95 kit for 6 quarts of sprayable material. So that cost $15.83/Qt or $63.33/per sprayable gallon.
Primer # 2 mix ratio is 1:1 kit cost is $120. Primer is $85, activator is $35. Kit makes 8 quarts sprayable. Gallon sprayable cost is $60/gallon. So always look, just because the price is cheap doesn't always mean you are getting the best deal.

 

Its epoxy, all epoxy have dtm capability.

 

Any advantage or disadvantage to using this or epoxy primer and a topcoat to coat chassis and suspension parts? Thanks

 

I have a car I am repairing the rust by welding in pieces ,there will also be some filler used in other places. The problem is I probably won't get around to paint for a year.I assume you would like the self etch initial coat ( on the bare metal) and then a good covering of epoxy.. If this is correct does the rest of the car need epoxy also when I get around to painting it. Thanks .

 

I prefer epoxy as a chassis paint, unless it will be open wheel car, then I would topcoat with polyurethane.

 

No need for self etch, just use epoxy.

 

Thanks. For some reason I thought I was using urethane but looked at the can and it is epoxy. Guess the hours of sanding is getting to me.

 

So the higher the solids content the thicker (more mils) per coat. Is that right?

 

No absolutely not, that is a trick some paint companies play, you can actually take vm and p naptha (charcoal starting fluid) and add in to a automotive coating to thicken, and this actually lowers the solids content. That is why its so important to read tech sheets and understand them.
Thickness has nothing to do with solids, solids is basically what is left after full evaporation of the solvents. Its the meat of the product.

 

Wow.
Now Just so I'm crystal clear on this,
Seems that Dino is speaking of "thickness" in term and context of dimension and quantity of mills built up. Are you speaking of "thickness" in the same terms or are you speaking of thickness as in viscosity?

 

Color me confused

 

Either way if its thick in terms of viscosity, or you put multiple wet coats of a thick primer but is low solids, you have the same outcome.
You can have a high solids primer and actually be thin. Its easy to show in person with a zahn cup (which measures viscosity)

 

Thanks PG, less confused.

 

Hey paint guru is this a good product? Deft 44GN-060 water reduced epoxy primer. what can it be top coated with?

 

Usually water based epoxy is used in military application, heavy Industrial etc and more of a top coat instead of a primer. I am not familiar with your product but I will try to look it up and give you a better answer. Did you run across some cheap? Check the manufacturer date. Water based has a short shelf life.

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yes I can get two gallons primer and catalyst for $65. will check date. how short is shelf life? Thanks!

 

Just read tds sheet, shelf life is 9 months

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so if it is older than 9 months is it useless? is this a product that will sand and top coat well or should I stick to something else?

 

Quick question. How does PPG DP90LV compare to DP90LF?