Powder Coating for Underbody

[sleek lemur]

Hi all,

Does anyone have knowledge or opinion in using powder coating as an alternative to more traditional methods of rust protection and vehicle longevity?

Research on the web seems very positive, but I have heard it said that moisture can enter where the coating has been damaged and eat away at the metal inside unseen.

I see there was a brief discussion on chrome powder coating some time ago.

[Army]

Originally Posted by sleek lemur

Hi all,

Does anyone have knowledge or opinion in using powder coating as an alternative to more traditional methods of rust protection and vehicle longevity?

Research on the web seems very positive, but I have heard it said that moisture can enter where the coating has been damaged and eat away at the metal inside unseen.

I see there was a brief discussion on chrome powder coating some time ago.

I think powder coating is a bit of a trendy thing that people do at the moment.

There's definitely a "powder coating and then there's powder coating" situation out there. When it fails (be it a good or bad powder coated surface) it traps water very efficiently. I think it traps water more efficiently than first generation rubberised undercoating systems (my Mercedes being a perfect example of this horror).

The type of rust you get on a rubberised undercoated vehicle is much worse than the rust you'd get from something that was say bitumin coated. A bitumin coated underside often has rust holes that are concentrated in areas where leaks happen / where water settles. A rubberised undercoated car ends up with massive longitudinal gashes of rot - capiliary action ensures the rust reaches parts that would not normally be reached!

Modern cars have struggled with these rubberised coatings for ages. I don't think many modern cars are going to survive like the cars that were built before the 1970s. Buying a second hand Ford Ka is like buying air held together with bits of plastic! Don't bother looking at second hand Nissan pick up trucks...

I've gone for a hard wearing paint for the underside of my PV so that if there is damage it is easy to repair. I don't think this is an appropriate fit and forget solution though - I expect I will spend a lot of time keeping an eye on it.

[sleek lemur]

Ingress of water is exactly what I was concerned about (obv!). But is rubberised undercoating what I was.asking about? I understand power coating to be affixed by way of electrical charge, therefore this capillary action wouldn't seem to occur.

[Laird Scooby]

Originally Posted by sleek lemur

Hi all,

Does anyone have knowledge or opinion in using powder coating as an alternative to more traditional methods of rust protection and vehicle longevity?

Research on the web seems very positive, but I have heard it said that moisture can enter where the coating has been damaged and eat away at the metal inside unseen.

I see there was a brief discussion on chrome powder coating some time ago.

I have a small (and i mean small) amount of knowledge on powder coating and trying to find an oven big enough to get your car in to cure the powder coat is going to be hard, if not impossible!

In case you don't know, once the workpiece (in this case your car) is prepared for the powder coat, the work is then hung up so that the powder can be sprayed onto it. As the powder leaves the spray gun, it's charged with a few kV +ve and the work is earthed. Opposite forces attract so the powder is attracted to the earth and sticks to it evenly. Then it is sent hrough an oven to cure it for about 10 minutes or until it "flows out" and changes from a powdery appearance to a smooth, almost liquid-like appearance.

Then it's cooled naturally. Theory says the coating will be uniform across all the nooks and crannies but any imperfection will give rise to chipping and damage from stones etc on the road can also chip it. Moisture then gets in between the coating and the metal and starts to corrode the metal.

However it should be pointed out the same happens with underseal and all other available underbody coatings.

In an ideal world, there would be big enough powder coating ovens and you'd be able to powder coat the underside of your car but the rest of the car would need to be stripped of all glass, trim, electronics, engine, gearbox and so on. Really a manufacture-stage procedure.

Although i've not used them myself, i've heard lots of good things about Bilt-Hamber products. Finding an underseal product from them would probably be your better option here.

[Army]

Originally Posted by sleek lemur

Ingress of water is exactly what I was concerned about (obv!). But is rubberised undercoating what I was.asking about? I understand power coating to be affixed by way of electrical charge, therefore this capillary action wouldn't seem to occur.

Once rust starts the method of how the coating was afixed is not relevant. Rust changes the physical composition of steel (as well as electric conductivity - not that that's relevant once the coating has been applied).

I compared rubberised undercoating with powder coating because from my observations it behaves in a similar if not worse way once water gets between the coating and the steel.

For example: I've seen many powder coated garden gates with vertical rusting.

Painted garden gates are easy to repair - powder coated gates are a bit of a nightmare (especially with UV damage - which before you say (!) - probably won't be a problem on the underside of a car).

In summary - powder coating seems to me to be one of those over hopeful "fit and forget" solutions that promises protection until things go wrong - which then makes repairs a lot more "effort involved"...

[Derek UK]

You can powder coat "parts", suspension arms for example, but you can't powder coat the underside of a car! Underseal is up to you. If the old stuff has been 100% removed and all rust removed or treated, a couple of heavy coats of anti rust primer needed before you make your choice about top coats.

[Army]

Originally Posted by Derek UK

You can powder coat "parts", suspension arms for example, but you can't powder coat the underside of a car! Underseal is up to you. If the old stuff has been 100% removed and all rust removed or treated, a couple of heavy coats of anti rust primer needed before you make your choice about top coats.

I don't wish to appear all internet warrior and argumentative but it really depends on the size of the oven.

Several of those discovery car programs show "custom car dudes" powder coating large items such as chassis.

The electrickery bit of the application is just to get the powder to stick to the surface - after that it gets melted into place.


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By the way - an alternative rough and ready solution to the general problem of how to protect the underside of a car could be to use cold galvanising paint such as Zinga.

Zinga did produce an advertising story about how they treated a Range Rover with their product before painting it (I can try and find a link if any one is interested) but as the galvanising coat is active - you get sacrificial corrosion and thus tiny amounts of movement - I've always wondered how a top coat of paint on top of the galvanised paint would stay put...

...I can, however, testify to the amazing properties of Zinga "on its own". I'm even considering trials of using it to treat rusty metal work instead of more conventional methods (such as sand / media blasting, chemical treatment etc)...

[Ron Kwas]

Forum;

I think Powder Coating is OK for protected parts, which live in a location where they will likely last and not need touching up after the coating has been somehow breached. For parts or areas subject to nicks and damage to the coating, I don't like it because as others have noted, moisture gets underneath and wrecks havoc even worse than a similar chip in a painted area...repair is difficult and a perfect repair is near impossible without a complete redo...no thanks...I like to do things once and right!

BTW...has anyone developed a spot repair technique for PC yet...perhaps with a heat-gun applying fusing heat only to a local/touched-up area?...sounds like a possible niche-market to me!

Army; I am interested in this Zinga you write of...please provide more info/links.

Cheers

[Army]

Originally Posted by Ron Kwas

Forum;

I think Powder Coating is OK for protected parts, which live in a location where they will likely last and not need touching up after the coating has been somehow breached. For parts or areas subject to nicks and damage to the coating, I don't like it because as others have noted, moisture gets underneath and wrecks havoc even worse than a similar chip in a painted area...repair is difficult and a perfect repair is near impossible without a complete redo...no thanks...I like to do things once and right!

BTW...has anyone developed a spot repair technique for PC yet...perhaps with a heat-gun applying fusing heat only to a local/touched-up area?...sounds like a possible niche-market to me!

Army; I am interested in this Zinga you write of...please provide more info/links.

Cheers

(As usual I manage to get the subject off on a tangent! Please ignore me if you find these "little asides" irritating)


Here are some links for Zinga information =>

https://www.frost.co.uk/how-zinga-wo...nising-system/

https://zinga.nl/cms/attachments/art...nd_CPS_ENG.pdf

Note the only reason I use this stuff is because it is cheap here in the Benelux countries. Other cold galvanising sprays / paints are available. I'd expect similar results from other products as essentially the effective ingredient is ZINC!

Zinga say their product contains something like 97% zinc - which I assume is a % of weight not volume...

...a similar product made in another part of the world should (I guess) behave in a similar way.

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I have found that you can slap it on all over - so long as the surface has been degreased.

I have found that it sticks better to slighty rusted surfaces rather than brand new metal.

It does a really good job of getting into "pore deep" uneven surfaces.

I've been experimenting with rusty junk that has been painted with this cold galvansing paint. Leave it for a few months and try to wire brush it off with an angle grinder and you won't find any rust "underneath the treated layer" =>

In my experience with rust proofing / rust eating paints that is never EVER the case!

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Downsides:-

Zinga - unless sprayed - has a surface finish that can be best described as "as rough as a badger's arse".

If you wanted to spray a top coat over the galvanised protective layer I think you'd be making a lot of trouble for yourself (if only from a starting point perspective)

If you wanted to paint on top of it then you need to get self ecthing primers or mess about with a solution which I think is called mordant solution. As said previously I'm NOT sure if painting on top of Zinga is such a smart move.

[Might not be a downside but] It changes colour with time - it starts out as a very light battle ship grey and turns into a much darker grey.

Upsides:-

Here at least it is cheap

It kills rust

If it doesn't work the first time because - say you really couldn't be bothered to wire brush before you painted - you can then get the angle grinder and wire brush out - give it a wazz - then paint more Zinga over the area where spots might have come through.

I think it is ideal stuff for say a traIler chassis - a boat - a garden fence - a fire escape.

It is industrial stuff but I think it could be used as a rust remover product (even though Zinga themselves don't seem to have cottoned on to this)

[Laird Scooby]

Originally Posted by Ron Kwas

BTW...has anyone developed a spot repair technique for PC yet...perhaps with a heat-gun applying fusing heat only to a local/touched-up area?...sounds like a possible niche-market to me!

Cheers

No but i think i may have come up with a rust remedy for rust spots. I dreamed it up several months ago and got the bits to do it, however my "guinea pig" has been away for nearly 6 months being MoT'd thanks to lockdown making the garage owners shut down in late December. They then conveniently "forgot" to phone me to let me know i could go and collect it.

If that's of any interest i'll post details in a few weeks when i will (hopefully) finally have the car back again!