Cure for flaking powder coat

[cabrioman]

Talking chassis coatings with Mike, he thought some people may be interested to see how I resolved my flaking powder coat problem, which quite a few of us have had issues with.

My Hunter rebuild started out with the intention of a quick clean up but the more I pulled off it the more powder coat disasters I found. A brief foray into Hydrate80 and POR15 paint treatment proved frustrating as the finish wasn’t what I wanted and it reacted or didn’t stick well to the powder coat.

The answer was drastic action, getting the chassis properly prepped and recoated.

The pictures below show the chassis in the blasting plant prior to recoating. I went to have a look at it at that stage and found where it had been blasted, the metal surface was textured like it had been etched, it certainly wasn’t like that where the original powder coat flaked off, so I can only assume the chassis were not blasted in that way when first coated.

The powder coating company applied a zinc powder primer coat before coating with black top coat as per the original finish.

Was it worth it? Well for me it was, I had to paint it anyway as I had cut the bulkhead to accommodate the BMW M20 engine and welded new repair sections in the transmission tunnel where it had been modified by Marlin to take an auto box conversion. And having it blasted sorted out the corrosion that had occurred with the original powder coat, something I could never have got as good by elbow grease, wire brush and sandpaper.

A tin of POR15 is £45, Hydrate 80 is £20, my solution was less than £350, more expensive for sure but I think worth every penny.

So just got to put it back together now, but at least all the holes are drilled!

[b_caswell]

Re: Cure for flaking powder coat

Looks very smart.

But years ago I was thinking of buying a TVR and every one I looked at that was more than three or four years old had problems with the powdercoating.
Yet my roadster which was painted with chassis black over red oxide has survived twenty four year and that includes quite a few dunkings in various fords.

[b_caswell]

Re: Cure for flaking powder coat

Tarr Steps Marlin in Tarr steps.jpg

[Robert in Cumbria]

Re: Cure for flaking powder coat

Sandblasting or gritblasting does impart a visible surface texture. You can peen welds and smooth grind marks with a powerful sandblaster, drill holes and smooth sharp edges even!

I have seriously considered galvanising the Marlin Roadster chassis but cost is the factor for me. I maintain a MII Landrover which has a galvanised chassis and it's as good as new.

I have seen several examples of powder coating which leave much to be desired. Properly done galvanising is forever, effectively.

If the item to be galvanised is already painted, the galvaniser dips the item in the molten zinc and that burns off any paint, it also shocks, which loosens, any corrosion which is then removed by pickling in acid. After pickling, the item is dipped and soaked in the molten zinc tank so that the zinc adheres to the metal.

Flat sheet metal can be a problem because (depending on the design) it can buckle with the heat. That can also happen with flat sheet metal being sandblasted, I once sandblasted an MG bonnet, what a mess, it was ruined, I filled it but it never looked right.

[cabrioman]

Re: Cure for flaking powder coat

Looks very smart.

But years ago I was thinking of buying a TVR and every one I looked at that was more than three or four years old had problems with the powdercoating.
Yet my roadster which was painted with chassis black over red oxide has survived twenty four year and that includes quite a few dunkings in various fords.

A quick google tells you everything you need to know about TVR powder coat, folklore says the chassis's were built and stored outdoors before going for coating, as they say the devils in the detail, or in the case of powder coat, the preparation or lack of it.