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Apr 10, 2023 17:16:40 GMT
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I'm stripping my hijet on the drive, I plan on pulling the engine & box & stripping all the paint & underseal off the underbody & the chassis rails with a knot wheel & wire wheel attachments etc. Once the metal is bare & cleaned should I etch or epoxy prime before laying on the gravitex stone chip? Or do I just go straight onto metal? I realise I'll need to do a bit of welding first...  |
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MOGGY
Part of things
Posts: 272
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Apr 10, 2023 18:23:17 GMT
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I’d always say a light coat of etch first.
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Total classic car pervert
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Marine grade stuff is good do you live near a harbour?
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Apr 11, 2023 10:13:44 GMT
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Gravitex is designed to go over bare steel or original paint just fine, on galvanised or aluminium it's going to need an etch primer first.
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Apr 11, 2023 17:19:49 GMT
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Gravitex is designed to go over bare steel or original paint just fine, on galvanised or aluminium it's going to need an etch primer first. I plan on using this which was recommended to me.  |
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jgtr
Part of things
Posts: 270 
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Apr 11, 2023 18:26:59 GMT
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Epoxy primer & brush it on, it’s specifically designed to go onto bare metal, no etch primer required. Then apply Gravitex over the top.
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Apr 11, 2023 19:03:11 GMT
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Epoxy primer & brush it on, it’s specifically designed to go onto bare metal, no etch primer required. Then apply Gravitex over the top. 2k? |
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jgtr
Part of things
Posts: 270
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Apr 11, 2023 19:17:54 GMT
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Yes 2k, most people use Lechler, it doesn’t contain iso-cyanates either. It works by mechanical bond hence no etch primer required, just need to sand the surface.
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Last Edit: Apr 11, 2023 19:21:41 GMT by jgtr
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Apr 11, 2023 20:45:59 GMT
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Yes 2k, most people use Lechler, it doesn’t contain iso-cyanates either. It works by mechanical bond hence no etch primer required, just need to sand the surface. Just looked on ebay & they do coloured epoxy primers. If I'm spraying chassis white should I get white primer? |
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Use grey primer, when it's all white you know that it's covered properly.
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Proton Jumbuck-deceased :-(
2005 Kia Sorento the parts hauling heap
V8 Humber Hawk
1948 Standard12 pickup SOLD
1953 Pop build (wifey's BIVA build).
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at200
Part of things
Posts: 86
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Apr 15, 2023 19:32:50 GMT
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I'd say brush on epoxy primer. Over on the mig forum they often recommend Jotun, though it's quite expensive imo. Depends how much you want to spend. I did my wheel arches with Gravitex using a 24 litre Aldi compressor and it went on really well. Overpaintable too I think.
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When I had to remove the badly applied paint on the underside of my Vitesse body I was advised that once I got it back to bare metal to use a brushed Zinc Phosphate as a primer. Also I was told that if using a wire wheel once you have finished with it go over the bare metal with an 80 grit 3M, the theory was that the wire wheel polishes the metal as it removes the paint and the 3M roughs it up to get a better bond with the primer.
\On top of the ZP I undercoated then top coated red from a rattle can.
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Vitesse 6 Saloon
Vitesse Mk2 Convertible
BMW R1150GS
VW Amarok
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jonomisfit
Club Retro Rides Member
Posts: 1,748
Club RR Member Number: 49
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Epoxy is two part, but usually amine based chemistry, so whilst not great it's not as bad as isocyanate based normal 2k paint.
I've found surface prep is key to adhesion of epoxy. If it isn't properly clean and suitably keyed you'll find over time it will start peeling in places. Irrespective if you've over painted.
A blast finish seems to be great.
The other thing with epoxy is it isn't fully UV stable so starts to shrink / crack / dessicate if it isn't suitably covered with other paint / covering.
I've also used high zinc etch primers with good effect before. I use electrox from built hamber which works well. Bites well and helps prevent further rusting as its fairly self sacrifice.
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