Powder coating

[wuckfitracing]

Right ho. I replaced the lower suspension arms with new ones 3 1/2 years ago. I had them powdercoated at a local reputable establishment. I know my local TVR guy has their new chassis powdercoated at the same place. However within this time they are already looking sh_t.
Being as the cars not seen salt and spends most of the time garaged up on a 4 post ramp, I am more than disappointed. I have been told that the edges should be rounded off so they take more powdercoat, is this the case.
Is there another process that others have used that works. If so how long has it lasted on yours. I dont fancy painting them though.
Im probably going to whip them off again and re do.

[pb450]

Mine were polyurethaned 4 years ago during a body off resto, after shot blasting and metalizing. Still as good today (though a little dirty) as the day they were done.

3 coats primer and 2 top coat, or vice versa. Can’t remember which.

[N7GTX]

During the construction of Milton Keynes and Belmarsh prisons, the steel company I worked for was asked by the main contractor to supply steel perforated panels. This we did. Then they said they wanted them powdercoated so I sent them to a Manchester area place and had them done. They looked very nice and the contractor was very happy. However during installation of the panels they were scoring, marking and chipping around the edges far too easily. In the end, we sent a team down to paint the panels. After this happened I never had anything powdercoated again. Very disappointed.

I would have them blasted, etch primed, primed then finished with Rustoleum. This is a good tough finish and comes in many colours. Available at B&Q or online.

[wuckfitracing]

Anyone galvanised theirs ?

[Engineer1949]

i still have components powder coated but hot zinc sprayed first then a high build primer and finally powder coat done at aerocoat in st.olaves norfolk.

john

[pb450]

Metallisation = hot zinc sprayed. Very good process.

[ChimpOnGas]

wuckfitracing said:

Powder coating never works well on sharp edges, powder coating is just that 'a coating'... unlike a wet paint or better still an etch primer, power coat doesn't actually bond with the substrate, it just wraps it. Any minor chip (which it's very susceptible to) and water will get underneath, after that very soon you'll be peeling sheets of powder coat off the component you'd hoped to protect.

On the earlier silver grey Chimaera chassis, TVR used a zinc phosphate primer before they powder coated the chassis, the silver grey powder coat job was better than they achieved on the white coated chassis too but it still fails around the welds because they didn't prep & clean them properly before applying the zinc phosphate primer.

The silver grey powder coated chassis still chips, but the zinc phosphate primer under it means the earlier chassis lasted so much better than the dreadful un-primed white effort that appeared in 1997. I've never been a fan of powder coating full stop, but if you do select it as your chassis finish you must make sure either a zinc phosphate or acid etch primer is used before the powder is applied or it'll only last a few years at best.

Powder coating is popular because it's clean to apply, cheap, and the investment in kit isn't that big... unlike a wet paint system you also don't need to be especially skilled to apply it and achieve a good looking finish. Of course looking good on day one and 'long lasting' are two very different things... personally I'd choose Jotun Penguard HB Epoxy Primer, or a zinc phosphate, or a good acid etch primer immediately applied to a freshly shot blasted surface followed by two coats of epoxy mastic top coat.

In my experience epoxy two component wet paint systems are always going to be infinitely superior to even the best primed powder coat job. I was always taught... "If a paint smells bad (in a chemical way) and makes you feel sick if you apply it without a respirator... that's the good stuff".

Anything two part expoxy is as tough as nails, epoxy mastic wet paints are very resistant to chipping as they contain a high content of plasticizer, plasticizer being a synthetic resin additive used in the paint industry to produce plasticity and flexibility and to reduce brittleness which is just what you need in areas that suffer stone impact like the outrigger tubes just behind the front wheels.

Jotun Jotamastic 80 is a very good quality marine grade 2 pack low VOC epoxy mastic paint as is their Penguard HB Epoxy Primer, however if you're hot dip or spray galvanizing the chassis you'll need a zinc rich primer to act as a tie coat between the galv and the epoxy mastic top coat, something like Rust-Oleum 3202 Galvinoleum Primer or Zinger, both would make an ideal tie coat.

Whatever you use to prime zinc you should always a pacifier first, this will be a zinc phosphate solution which contains a small amount of copper salts that will turn the galvanized surface black but will also remove all the elements that leach out of fresh galv that mean primers and paints just fall off it.

The thing people overlook when galvanizing their chassis is how it actually works, galv is a sacrificial cathodic protection so it only starts working when it's exposed to oxygen and air, sat under a layer of paint it actually does nothing at all but it is there ready to start doing it's sacrificial thing if the top coat is breached. Once it does start to work it can actually lift any top coat you've applied over it so this should be considered if your contemplating hot dip or spray galvanizing your chassis.

[wuckfitracing]

Thanks for detailed reply as usual. Mine is a silver chassis as its an early 430. However I fancied doing the suspension bits in white along with the hubs being gold. I now think I will get the suspension arms stripped and galvanized without putting any paint or laquer over them. My car transporter trailer I used for racing my offroader for 10 years was new when I bought it. It was galvanized and still looked like new when I sold it 10 years later. Even with all the miles and the constant jet washing of various mud/brake fluid/gearbox oil/antifreeze/blood off it. I think Im over powdercoating for now, it just doesnt last.Random picture of rear end as I cant find a picture of the front .

[TJC46]

Here you go....plenty of reading material for a Sunday.

http://www.pistonheads.com/gassing/topic.asp?h=0&a...

[Steve_D]

wuckfitracing said:

Anyone galvanised theirs ?

The hot zinc spray mentioned elsewhere is zinc melted onto the metal surface using either flame or plasma arc equipment. It is very nearly the same as galvanising without the hassle of having to drill pressure relief holes in all the tubes. The finish is very slightly porous which gives a good key to subsequent application of paint or powder coat.

Steve