rob_bell

rob_bell

Well-Known Member
Question as per title: I’m going to recondition some subframes and will get them shot blasted to get rid of all the flaking surface rust.

not sure whether to powder coat at the same time or paint?

powder coating is tougher, but if chipped can trap moisture and exacerbate rusting (or so I’ve read - seems plausible looking at cheap metal garden furniture).

What is the consensus view on this? I had planned on powder coat but might just paint now…
 
I did half and half!!
Powder coated springs and subframes and roll bar. Painted hubs and adjustable arms to save having to remove bearings and clog threads.

Subframes still perfect, zinc based paint already rusting.
Yes powder can allow moisture under if split, but not seen it if we'll done. Cheap furniture gets, well, a cheap coating.
Also, you can zinc primer powder for a better undercoat and protection.
 
Cheap garden furniture made out of chinesium is nothing to go by. Cheap low quality steel will corrode from the inside out due to impurities within and the coating will fall off. Powder coating will outlast paint coats many times over. Provided the steel quality is good and the powder coating is done diligently.
Powder coatings can be repaired with a touch up paint but its unsightly (used to do it on industrial fabricated coated process pipework). Both powder coated finish and wet paint finish will chip and need repairs when this happens.
 
Thanks guys - that’s really reassuring. I’ll aim to keep with plan A, so long as it is affordable to powder coat the subframes (Londinium tax!)

I’ll get some quotes…
 
Not sure if this is helpful or not, but I work in highways, and we stopped using powder coated street furniture a long time ago. We weren't using cheap Chinese stuff but it did used to crack and the steel beneath would rot due to the reslting moisture ingress. I suspect that UV was the problem causing the powder coating to fail so a subframe may well be just fine!
 
I'd chose Bonda primer applied to grit blasted steel instead power coat any day.
Power coat is applied to untreated grit blasted steel, which if chipped, will corrode, often unseen.
Bonda primer simply doesn't come off grit blasted steel, so even if a top coat comes off due to impact, the Bonda primer holds fast, preventing rust.
 
The thing with powder coating, everything you don't want done, has to come off and you can't touch it up. Well, you can, but it won't last
 
Thanks - hmmm - still not sure which way to go now… blast the frames definitely, but whether to paint or coat?

I’ll get quotes and consider the time I’d need to invest…
 
I remember seeing a TVR (on Wheeler Dealers I think) where the chassis had been powder coated and still rusted very badly.
What about having it galvanised?
 
I'm guessing you might want a nice smooth finish but if not, what about the paint landylee used on the underside of his tub.
Its a mottled paint which would cover impurities, Raptor. Probably more suited to wheel arches though if I'm honest.
Otherwise a nice hardwearing 2 pack black..
 
Nodge68 said:
Bonda primer.https://www.ebay.co.uk/itm/Bonda-Ru...=p2349624.m2548.l6249&mkrid=710-127635-2958-0 , then a decent underbody protection paint, and forget about it for many years. ;)

I'm going to do the FL2 underbody with the same treatment this year, because I know it works.
Click to expand...
Hi Nodge, is that Bonda primer quite thick (or on the thin side) ? Now I've had the rear quarter replaced on my D2 I intend to do the rest of the chassis & some bits on the FL. I have used that Omnicote stuff which goes a long way so was wondering if I could getaway with a litre, cheers.
 
Andy Warren said:
Hi Nodge, is that Bonda primer quite thick (or on the thin side)
Click to expand...

It's about the same viscosity as good quality emulsion paint.
Bonda primer does settle out in storage, and if it appears thin, with need thorough mixing, as the thicker components settle to the bottom.
 
Nodge68 said:
It's about the same viscosity as good quality emulsion paint.
Bonda primer does settle out in storage, and if it appears thin, with need thorough mixing, as the thicker components settle to the bottom.
Click to expand...
Thanks for that, it sounds a bit thicker than the Omnicote stuff so I'll order a litre for when the weather's warmer (soon I hope):).
 
Andy Warren said:
Thanks for that, it sounds a bit thicker than the Omnicote stuff so I'll order a litre for when the weather's warmer (soon I hope):).
Click to expand...
It is quite thick, but it's thin enough to creep into gaps between panels, and protect from rust between them.
Bonda works best on blasted or heavily abraded metal, and not applied over a rust treatment, which coats the metal.
I'd remove rust by mechanical means, then apply an acid rust killer to remove all traces of rust. The metal can then be dried thoroughly, and the Bonda applied with a brush.
Once applied, its very difficult to remove, so only apply it to where you want it. ;)
 
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