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MG MGA - Chassis Primer - acid etch v 2-pack v POR15 type

Much to my disappointment I have to start over priming my chassis. It turns out that the acid etch primer I 'acquired' from work had gone-off! It would appear that the activator was out of date (which no doubt was why it surplus to requirements).
So rather that having a base primer that is highly bonded to my chassis, the stuff is now flaking-off (or does very easily).

Now that I have to start again, I am re-thinking with route to go? Do I stick to my original route (with some new etch primer) and multiple coats of zinc & red oxide on top of that or switch to 2-pack or POR15 type. Rust is not an issue as the chassis has been shot blasted.

As ever, your opinions and experience with these products, would be much appreciated.

Chris Bond

2 part epoxy is very good. PPG Omni-Au. 2 coats brushed on followed by 2 coats gloss black enamel.
Art Pearse

Here are some photos of my '61 "A" chassis (before and after)that was sand blasted and Por15 coated.
I really like the POR15 it is easy to apply by brush looks great and is as permanent as it gets. (just always use cloths you dont mind throwing away and use gloves at all times when working with it. How resistant is POR15? When I replaced my body sill I coated the insides of it entirely with POR15 , then I decided to have the entire car body dip striped to remove all the old paint under coating and oil the metal striper called me back and said he would be unable to get the POR15 removed with the acid dip strip! I told him I was glad because I did not want that removed. It has to be pretty tough stuff. I have found that grinding wheels will take it off, wire wheels with a lot of time and effort will get though it eventually and 120 psi sand blaster will take a lot of work to remove it (unlike normal paints that you just pass over with the blaster and the paint is gone). Other than that make sure you only paint things you want to permanently keep painted. I have now painted every bracket or steal surface on the "A" including dash, demister vents,engine mounts,heater and all associated parts,fuel tank, all steering components, springs, and suspension (anything steel I could sand blast or wire wheel strip, I have coated with POR15)
Chris Velardi

Check out ZeroRust. I'm five years post restoration with not a hint of failure anywhere.
Follow the links.
D Sjostrom

Had my chassis grit blasted and etch primed a few months ago. I then put on Epoxy-Mastic 121 from Rustbuster, a two part epoxy paint, which I also put on the inside of the propshaft/gearbox tunnel. On top of this went a couple of coats of chassis enamel.Use a colour other than black for the epoxy so you can see which bits you have missed when you spray the black enamel topcoat
S Ash

A second vote for POR15. My chassis was sandblasted and POR15 sprayed, it looks great. Also easy to touch up if necessary, but you have to scuff the surface first.
G Goeppner

Hi Chris. Back in 1980, I sprayed my chassis wth Dupont Imron, a 2 part polyeurethane paint. They use this stuff on Jumbo jets bacause it is so tough! 29 years after painting my chassis, the Imron still looks like new. Imron is highly chip resistant. On the downside< Imron is expensive and is hazardous to spray. One needs an extremely effective respirator, or an air fed mask. I have heard excellent things about the POR product, but have never tried it myself. Best of luck! GLenn
Glenn Hedrich

> Imron is expensive and is hazardous to spray. One
> needs an extremely effective respirator, or an air fed
> mask.

ONLY use the air fed mask when spraying Imron or other two part polyurethane paints. I am aware of no filter type respirator capable of stopping the hazardous fumes, which can kill you quickly.
Del Rawlins

Really nasty stuff.
As Del states IMRON is hazardous. If you can smell it you have exceeded the safe levels of exposure. DO NOT USE WITHOUT AN AIR FED RESPIRATOR. NO mask is good enough.

This info is from Dupont.

Warning --VGM-6005 Activator contains aliphatic isocyanates.

Danger! Vapors and spray mist are harmful if inhaled. Overexposure may cause lung injury , allergic respiratory reaction, dizziness and nervous system damage. The effects may be permanent. These materials are flammable and they may irritate eyes and skin.

VGM-6005 contains aliphatic polyisocyanates and hexamethylene diisocyanate monomer. The activated mixture contains all of the components of the activator plus esters, ether esters and petroleum distillates. Do not breathe the vapor or spray mist.

Wear a respirator, eye protection, gloves and protective clothing while mixing activator with enamel, during application and until all vapors and spray mist are exhausted. Wear a positive-pressure, supplied-air respirator (NIOSH/MSHA TC-19C) during the spray application (or brush or roll application in poorly ventilated areas) of this product.

For mixing and for brush and roll application in well ventilated areas, a negative pressure, vapor/particulate respirator (NIOSH/MSHA TC-23C) can be used provided the wearer has been properly fit-tested for the respirator . Follow respirator manufacturer's directions for respirator use.

Individuals with lung or breathing problems or prior reaction to isocyanates must not be exposed to vapors or spray mist. Do not get in eyes or on skin. Keep away from heat, sparks and flame. Vapors may cause a flash fire. Use only with adequate ventilation. Keep the container closed when not in use. If you have any questions regarding the safe handling of these products, call (800) 441-7515.

Consult the Material Safety Data Sheet for this product prior to use.

R J Brown


I have used POR-15 with very good results. Like others have mentioned, consult the MSDS for safety precautions. The manufacture's web site says, "We recommend the use an organic vapor
particulate respirator, NIOSH/MSHA
approved, when applying POR-15. If you are
spray painting, you must use an airsupplied

These coatings really stick, I got a small dab on my hand and it took 2+ weeks for it to wear off. Saving partially used cans is difficult at best. I have had some luck with Bloxygen (Argon gas in a sray can) to slow the oxidation process in partially filled cans. Be sure to use a plastic film between the lid and can.

Good luck.

jjb Backman

Can you explain how you used Bloxygen (Argon gas in a spray can) to slow the oxidation process in partially filled cans ? The only effective thing I could do was buy the very tiny 4 oz cans. If I know I only need to paint a small part I have one 4 oz can with 2 self taping screws in the cap take them out pour some out and re seal asap. I only use a brush with POR15. It is very thick or heavy in solids probably why it is so effective . Nice part is even with a brush it self levels to a beautiful finish (I only wish it was UV stable so you could use it on exterior parts without a top coating.
Chris Velardi


I have used the bloxygen for some other oil based finishes so I tried it with the POR-15. I had purchased a pint of the POR-15 and had only used about 1/3 of the can. The first couple of times I had a clean lid so reused the existing can. To use the Bloxygen, you just put the lid on loosely, and slip the noozle tube (same as on a can of WD-40) under the lid and hold down the spray button for 2-4 seconds. The idea is that the heavier Argon displaces the atmospheric gases and that the Argon is inert with respect to the POR-15. Then seal the can.

The third time I did not have a perfectly clean lip on the can and ended up destroying the can to get it open. With the smaller amounts I used a smaller glass jar again with the bloxygen. Again make sure the the lip is 100% clean. Sometimes had a light surface skin that could be removed with a stick. Also have been careful to store the glass container in a location that would not matter if it broke.

So far I have used the process five times and have almost finished the can. I suspect that I am at the end of the road for what is left.

At $30 USD a pint this stuff is too expensive to waste. I am not sure what a can of Bloxygen goes for these days, the can I have must be getting on ten years old. I keep wondering when it will go empty.


jjb Backman

If you have a MIG welder, you could also use that gas to inert the can.
Art Pearse

Thanks Guys.

All good stuff as always.

Just spend the weekend experimenting with some 2-pack stuff, called Epoxy Mastic from Rustbuster (UK), on the inside of the boot (trunk). Intended to be used on wire brushed rusty surfaces but I cleaned off most of the rust before applying. Used a brush to apply (but can be sprayed) but not overly keen on the brush finish. On the Rustbuster web site they recommend painting Zinc primer direct to the chassis with Epoxy Mastic on top.

Stating this....
EPOXY-ANODE zinc rich epoxy primer offers the very best in Cathodic and Barrier protection to BLAST CLEANED STEEL. To form part of a paint system with EPOXY-MASTIC.and other high performance coatings within our range.Epoxy-Anode is a self repairing primer containing 93% Zinc solids bound into an epoxy resin. If a scratch appears on the steel that goes through the topcoat and primer back to bare metal the zinc in the primer will react with the steel, this reaction will form zinc salts that will heal the scratch maintain the barrier and the steel will not rust.(Cathodic Protection).

Is this marketing BS or does Zinc primer do this?


Chris Bond

Something doesn't smell right. The epoxy mastic is intended to be painted on rusty metal, BUT, they recommend priming first on blast cleaned steel??? Obviously then, the epoxy mastic is pretty crap!

The self healing properties may work on very minor scratches, under laboratory conditions, but in the real world?

I think I prefer the sound of POR-15 painted on a blasted surface over painted with a 2 pack enamel (for UV protection) or colour coat (on the body underside.)
Neil McGurk

Hi Neil

Where's the best place to get POR15 in the UK?
Chris Bond

You can get POR-15 from Frost Restorations in the UK, google will bring up contact dtails etc. I used silver primer and black top coat. Very impressed.
C Manley

Hi Colin,

The only problem is that Frost are showing out of stock and have been for some weeks!
I'm thinking of going the Epoxy Mastic route as now the coat I have applied to the bodyshell has cured, it does seem very tough.
Chris Bond

Chris. Take note not to use POR-15 from a tin that has been open longer than a few weeks. I painted my E-type using POR-15 and used always fresh tins to do each stage (inside, underside, outside, bonnet etc.). I however missed the 2 wings as I was still panel beating and ended up using a can that had been open for 4 months (albeit tightly shut after use).
The paint went on well but I noticed a small repair was required and so needed to strip back some paint again. The paint just peeled off the sandblasted surface like a banana skin. This got me worried and I tried other areas on the car but luckily they where okay. The parts painted with the old pot of paint where the only ones with the issue. Half a days work wasted but better to know before final painting?
I would otherwise rate highly the ability of POR-15. I have used it on many projects with good effect.

Neil Purves

With POR-15 I always use a bunch of small cans to divide the paint into. Make absolutely certain that there is zero paint in the groove or you will not open the can without tearing. I then ,after filling it up add marbles to completely fill the can to the very top. with care then install the lid. Marbles displace the POR-15 enough to eliminate the air.
Sandy Sanders

Thanks again guys.

I have had a rethink and purchased a tin of POR-15 to see how it compares with the 2-pack stuff.

Your comments about resealing and removing the air from the tin are duly noted. Will CO2 work instead of Argon or does it have to be an inert gas?

Chris Bond

These (POR and other one can types) are moisture catalyzed urethanes, so the most important point is to eliminate water in the air. Try to do all your opening and transfer functions on very dry days - indoors in the winter with central heating on is good. The inert gas is good mostly because it's very dry; oxidation is not much of a factor as it was with older enamels.

I find POR to be over rated and very expensive, compared to numerous similar products. I've had good success with Masterseries, at half the price, and no "other" expensive potions to buy. You will note that you never seem to be done buying required or recommended stuff from POR, all overpriced. Masterseries has a super silver sacrificial primer, can be used under anything, and super glossy UV tolerant topcoats.

FR Millmore

I've used plenty of POR over the years, and never bought anything from them other than the cans of paint. So I'm not sure what you mean about never seeming to be done buying stuff from them. I've posted my impressions here before, but IMO it is a good product, even if it doesn't quite live up to their advertising copy. Sandblasting the parts prior to use is a must, as is a good quality topcoat to protect the POR from UV light, which will cause it to deteriorate.
Del Rawlins

I have used plenty of POR 15 in small amounts, taking care to close it tightly. It may be because I keep it in my beer fridge / cold and take it out day before I plan to use it. The present 4 ounces can I just used must be 12 months old and used 10 or more times. No problem.
m zazvorka

Never bought anything but the paint from them myself either, since at the time that's all there was. Last time I had my hands on their printed material, they seemed to have a whole bunch of stuff, washes, metal conditioners, reducers, etc., with a murky sort of implication that it might not work if you didn't use all that, and it would be your fault. Hate that kind of thing! And seems to me that "POR" meant "paint over rust", but as we all know, it's not so good at that.

Masterseries actually does work over scraped or wire brushed surfaces, though blasted is of course better. It's originally made for painting bridges and such. Most of their stuff is UV resistant, except a "chassis black" variant. I've never used it, but I hear "Rust Bullet" is very good too.

FR Millmore

To some extent, that's kind of standard; most paint companies will recommend only using products together that they have tested and know are compatible, and oh by the way which they will be happy to sell you. Since one of my personal curses is paint that won't dry, I tend to do what they say, particularly when I will have to buy the support chemicals from someplace anyway.

With the POR, I am comfortable doing it the way I do, because when I started using it, I didn't have access to any of their other proprietary stuff, and had to find out what worked for me by trial and error. I think the bottom line, is that any paint designed to be the initial coat, is going to be happiest when applied over clean, sandblasted metal. I've tried it over rusted steel, and it just didn't hold up. I've tried it without a topcoat, and it eventually went away. Things that have been both sandblasted, and topcoated, have held up. Maybe on the frame of a car that only comes out in nice weather, and lives in a climate controlled garage you can get away without the sandblast like they claim, or even the topcoat. But for anything exposed to the elements or rough use? Forget it.

And I am not at all saying that there isn't something better out there, I would certainly hope that there is. The only real advantages of the POR are that it is available to me locally (try getting small quantities of hazmat shipped to Alaska sometime!), and I know that I can make it work if I use it a certain way. I'd have to have some fairly compelling reasons to make the switch to some other product that may or may not work out for me. Especially if I do something wrong, or it just doesn't live up to expectations, and I have to re-do a lot of work. I'm already past that point of the learning curve with the POR. It's a good product, so long as you keep in mind that there is nothing magic for sale in the realm of automotive restoration products.
Del Rawlins

Hi I am looking to have my frame clean up to bare metal and then paint it. Where I am confused is to prep the metal. "Metal ready" from por15 and "metal clean" by PPG cals for water rins. My experience, rinsing small parts, is rust in few minutes. I can not see myself to be able to dry the frame that fast. Anybody has any suggestion, experience solution?

m zazvorka

You can coat POR15 over freshly sandblasted chassis without any other prep. I dont Think you can get a better surface for any paint to bite into than a sand blasted one.
Chris Velardi

This thread was discussed between 17/07/2009 and 12/08/2009

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