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MG MGA - Powder coat vs POR

Hello all, like several others on this board I too am getting ready to remove the body off my A. I am wondering what the general consensus is on powder coating the frame vs. POR 15. I have done some shopping around in my area (Atlanta Ga.)and found that powder coating is really not that much more money(considering I will have to have someone sandblast it either way). Any suggestions or insight is greatly appreciated. Thanks....... Don P.
D.S. Prince

I have done it both ways. I know others have had good luck with POR 15 but I have not. After a few years some areas of the POR 15 have peeled. It was probably user error but I know I am not alone.

As for powder coating...I have no complaints at all, not to mention my labor was taken out of the mix! On my last car I had almost every item that was black coated. What a joy putting it back together, it was like Christmas unwrapping each shiny part for assembly. And yes I even did the front springs.

Peter
PC Cirillo

Don, I did my sandblasted frame a year ago with POR 15 semi gloss, and am happy with the results, albeit its only been a year. A friend of mine did his GTO chassis about 10 years ago, and it still looks great today. I have no first hand experience with powder coating, but I hear that its harder to touch up the inevitable stone chips you'll get because its a thicker coating than POR 15.
G Goeppner

I did POR15 and stand by the product. If a lot of the frame was exposed I suppose I would consider Powder coat. The few areas that are exposed, as in the engine bay, can easily be touched up. It is really good on the inside of the fenders. Although not "original” The dark color contrast against the beautiful curves of the fender are not diluted. POR is great for protection against stones as well!


WMR Bill

I powder coated the frame, suspension, diff, drive shaft, basically everything structural on the car that was originally black. I'm very happy with the results - five years on, everything still looks brand new.
Mark Lambert

Have you considered zero rust? A friend recommended it and has had good experience with it. I just sprayed my frame with it yesterday, so can't vouch for it myself.
There are a number of sites around which compare POR vs zero rust.
Jonathan
jonathan eagle

Remember that POR oxidizes (badly) when exposed to sunlight. It must be topcoated to prevent this. Granted, a frame doesn't get much exposure, but I think topcoating is a good idea anyway.
Cheers,
GTF
G T Foster

Powder coating, if done right, is far superior to any paint for two major reasons: First, after sandblasting, the metal is solution degreased and then submerged into an etch bath - either phosphate or chromate that converts the iron oxide (rust) to the corresponding more chemically inert iron phospate or chromate compound. Since the item is immersed, the degreasing and chemical conversion has access to areas that painting does not. Second, the powder coating process involves electrostatically attracting powdered resin to the metal item. The electrostatic coating again reaches places that simple painting cannot. The final step involves melting the powder resin onto the metal substrate. The heat causes the coating to flow into small areas as well as volatilizing any low boiling hydrocarbons (i.e., grease and oil) that might have remained behind the cleaning process and thus gives a cleaner surface for the coating to adhere to.


From a chemist perspective, anyway...

Steve
Steve Brandt

I have used a lot of POR-15 over the years; I have had it work, and I have had it not work. The keys to having it work are surface preparation and topcoating for UV protection. The people at POR say that you can paint it right over the rust, after some rudimentary cleaning, but this is a lie. There is still no substitute for sandblasting as surface prep. This will give the surface enough tooth for the POR to really grip and hold. Otherwise, the first chip will cause the old rusting to re-start, and it will run under the coating, which will then peel off and the whole job will need to be re-done. And let me tell you, removing old POR-15 can be a bitch.

The second issue with POR is the need for a top coat, otherwise UV light will kill it. You may get away without a top coat on a chassis, but I would still take the extra time to do it while the car is apart. I almost always use silver colored POR, that way I know when I am getting good coverage on my top coat.

Anyway, following these two steps, I have always gotten good results from POR-15. Leaving either of them out, I have never gotten good results.
Del Rawlins

I have just a few weeks ago finished my chassis (sandblasting and them metal replacement and repairs). Afterwards I primed and used Eastwoods Extreme Chassis Black.http://www.eastwoodco.com/shopping/product/detailmain.jsp?itemID=14348&itemType=PRODUCT&iMainCat=400&iSubCat=402&iProductID=14348

I looked at powder coating but decided against it for three main reasons.

1. Powder coating can leave a finish that is TOO shinny and not "correct" for the car. Granted this may not be a negative for some.

2. More importantly, painting it allows for future repairs to have the same finish as the now "original" finish. Repainting over powder coat is a pain in the ...
I can also paint the suspension bits and pieces etc. with the same paint and same finish.

3. Powder coat can be brittle and chip easier than a paint designed to be a little softer and more flexible.

Of course the advantage to powder coat is an easy durable finish. Eastwood now has a newer finish that has ceramic. Looks interesting.

Additionally spraying your own lets you do things in stages. Very beneficial for the home bound job. All in all I’m very pleased with the way mine has turned out and recommend the product.
GD Glenn

If you decide to go the powder coating route and the same firm does the sand blasting I would suggest you ask to see the frame after blasting and before coating. There will be a tendency for the blaster to skimp on his work if he knows any bits of rust he hasn't removed will be covered up before the customer sees them. This is my experience. Mike
m.j. moore

Add to the above:

The chassis used two quarts of top coat. I also bought several aerosal cans for things like the petrol tank staps etc. I have a home bench top sand blaster and as pieces are cleaned they'r primed and painted. Works great. Two great pieces of equipment for restoring cars are a parts washer and sand blaster. Can't recommend them enough.
GD Glenn

> 1. Powder coating can leave a finish that is TOO
> shinny and not "correct" for the car. Granted this may
> not be a negative for some.

You just have to specify a semi-gloss powder to get the finish you want. If you are still worried, you can ask to see a sample part coated with it.
Del Rawlins

Regarding Steve B's post, sand blasting, acid etching and chemical cleaning / degreasing are not part of the powder coating process, and are therefore not an advantage to powder coating over any other form of finishing. These are separate processes that can be performed on any frame before any type of paint is applied. Sand blasting should be done before powder coating, POR-15 or paint.

Having used powder coating for 15 years and POR-15 for about three, my observations are this...

Powder coat is durable and comes in many flavors. It is the easiest way to refinish parts because you simply drop them off and come back when they are ready. It is difficult to touch up because you have to use a regular paint, which will not exactly match the powder coated finish. It will not hold up to extreme heat but does a good job on most items. Scratch resistance is better than standard paint but not quite as good as POR-15, which is hard as a rock.

POR-15 is extremely durable yet flexible enough to be used on springs. Overall it is much harder and tougher than powder coat. It can be brushed onto your parts and will self-level to a smooth finish. There are fewer color options for POR-15 but most people use either flat or glossy black anyway. Touch-up can be done at any time using the same type of POR-15 and a small brush, although it's very unlikely to chip considering how hard the stuff is. A top coat is necessary for any parts subjected to direct sunlight, or long-term reflected UV. POR-15 can also be sprayed, which is a good way to get inside parts where brushing (or powder coating) cannot reach.

Removal of either powder coat or POR-15 is difficult, but POR-15 is definitely more so.

I use powder coat on cosmetic pieces which will not be subjected to abuse and therefore will not need to be touched up. I use POR on those which will see a lot of abuse, like suspension parts.
Steve S

Del is correct about semi gloss or satin in powder coating. It's not a mistake using either one. Something else that was a consideration for me was the powder coater was 20 miles away and known for not having things ready for weeks after promised. Also I like being able to paint the pieces as I have them ready.
GD Glenn

Just a small tip. I did por 15 my frame, inside my fenders,and many unseen misc parts. However I would advise powder coating the brackets that secure the master cylinder and everything below it. Brake fluid is so corrosive and it will leak when you least expect. It then travels all the way down to your best pair of dinner shoes! Then you know have to deal with your wife for destroying another piece of apparel. Powder coat is quite resistant to brake fluid.
WMR Bill

WMR,
Did you use DOT 4 or Silicone ?
I have always understood that silicone is preferred because it wont attack paint (and shoes)
David
D C GRAHAME

One more note, POR15 will bond to the metal surface, preventing rust from forming underneath it. If it is scratched (good luck!) it will not allow the rust which forms in the scratch to migrate under the paint. Powder coating will not do this.

Just one more thing to think about.
Steve S

Dave, I am using Castrol Dot4. I guess I have just alway used it. can you just convert by draining and adding silicone?
WMR Bill

> One more note, POR15 will bond to the metal surface,
> preventing rust from forming underneath it. If it is
> scratched (good luck!) it will not allow the rust
> which forms in the scratch to migrate under the paint.
> Powder coating will not do this.

I have to call bullsh*t on that. I painted a new front bumper for my Jeep with POR-15, over lightly rusted bare metal like the directions say you can (I thoroughly de-greased it first). Topcoated it with a semi-gloss black enamel, and within a couple years, everywhere that the paint had been chipped, rust was starting and not long after that, it did migrate under the paint, and I ended up stripping all of the POR off. This time I sandblasted it, recoated with POR-15, and then topcoated that with Herculiner (truck bed liner) for chip resistance. I did that 3 years ago, and haven't had any problems with the bumper since. Granted, my Jeep is an off-road vehicle used in a pretty corrosive environment, but it highlights the fact that POR-15, while a good product, does not quite live up to its claims.

FYI, I re-blasted some powder coated side guards at the same time, that had gotten chipped and the rust migrated under the coating in the exact same manner as the POR-15 coated part. Bottom line, surface prep is important, but the environment in which you operate probably has as much to do with the results you will get as what you use, or how well it is applied. And a Jeep in coastal Alaska is maybe a better example for comparing POR and powder than an MGA in California. 8^)
Del Rawlins

WMR. Not sure about this. I have heard that it is not wise to mix and that it is advisable to flush through before putting in silicone but also that the rubbers in the system do not like being subjected to changed fluid and should also be changed.
Perhaps others (Barney?) could comment.
David
D C GRAHAME

Del, I've had the opposite experience. I've never painted POR or any other product over rust (and never will) so I can't comment on that, but I do know that all paints including POR (despite their claims) work better on a blasted surface. POR also requires acid etching (they sell a product in a spray bottle) for maximum bonding to the metal.
Steve S

I think it just goes to show that the particular coating chosen is far less important than the surface preparation.

I am most likely going to go with powder coat on my frame, even though I am set up to sandblast and paint it myself. The local powder coating shop sandblasts everything they do, and the cost vs. hassle of doing it myself seems to favor just having it done. Plus, a large part of the shop's business is aviation parts (Super Cub frames, etc), and if there are any issues with quality, word gets around in the aviation community very quickly here.
Del Rawlins

OK, so can anyone that has done this tell me the amounts that should be ordered to cover the MGA chassis, diff, driveshaft, and suspension?

I'm looking here:

http://www.por15.com/

but if anyone knows a place cheaper let me know, I'm still just doing some preliminary research but based on this thread POR15 seems to be the best avenue for me so I'm going to be looking for a source and quantities of POR 15, topcoat, and metal prep.

Thanks,
Christopher

Christopher Wilson

Half of one quart is enough to put three coats on the entire front suspension, cross member, rear axle, brake plates, etc of an MGB. I would think that two quarts would cover you pretty well. Just a semi-educated guess though.

Del, I fully agree about the "hassle factor". Painting is one of those things that is so much nicer when someone else does it.
Steve S

Thanks Steve. BTW -- are you the same Steve that documented Uberfish?

Cheers,
Christopher
Christopher Wilson

I have had only one experience with powder coating and, unfortunately, it was a disaster. The offending item was a fuel tank from a 1952 Cyclemaster. The two halves of the fuel tank were soldered together. During the powder coating heating process they fell apart! I ended up gluing the halves together, sealing the inside and 2-packing the exterior. Image of a Cyclemaster attached.

Not an MGA Chassis problem - I trust!

Steve



Steve Gyles

That is very cool Steve! I have had my eye open for an older "Whizzer"
WMR Bill

Bill

It could come into its own again with current fuel price levels - up to 240mpg (provided the gluing holds out!)

Steve
Steve Gyles

"Thanks Steve. BTW -- are you the same Steve that documented Uberfish?"

Yes, that would be me. That seems like decades ago! I guess the legend of Uberfish has made it to the MG forums. :)

Steve G, the tank was probably lead soldered. Powder coating heats the parts to around 400-degrees F, which is more than hot enough to melt lead solder. Your powder coating shop should have known that! Bummer, but at least you got it repaired.
Steve S

This thread was discussed between 18/09/2008 and 23/09/2008

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