I've never had a lot of luck with painting over galvy - even using the correct etch primers. When I replace mine, which have started blistering, I'll leave them unpainted.
 
galv as well as covering steel protects it by acting as sacrificial anode and so whatever you paint it with will come off eventually
 
You can paint it, have done so with the rear crossmember of my galv chassis. I coated it with mordant solution, sometimes known as T Wash, leave it for a couple of hours and it will go black. Then wash it off, allow it to dry then I sprayed an etch primer, then I sprayed it with Pro cote primer, then a satin black and its come up well. Companies that provide galv bulkheads wouldn't be too popular if every single one of their products lost the paint quickly.
 
i didnt say quickly but once in damp atmosphere it does come off galv coating isnt like paint not necessarily all over but at weakest place ,its the same effect as why zinc anodes are used on ships ,
 
Your right as usual James. It does take time to corrode but I'd still waxoyl it incase of weak spots.
 
Why bother... if a problem arises you will see it straight away and its something less to worry about
 
to paint the caps costs £££, to leave 'em alone costs nowt! I know where my money would be! I thought I was doing the right thing by leaving my new chassis a couple of months to weather before building it then painting it, but alas it was a complete waste of time, 'cos the paint has still peeled off in big chunks!
 
dulux do a primer that will go straight on bright galv then the do a gloss or satin top coat not cheap only comes in 5ltr sizes in the metalshield range.Ther is also a small company downsouth think ther called barnpaints do a lot of problem solving paints (msp) multi surface paint will go straight on galv about 15 quid in standard colours about 25 quid i think in ral and bs colours per ltr.galv needs to be weathered 2 months and degreased.Both new products so havent had a lot of feed back at mo.
 
galv while in damp atmoshere sheds as part of gavanic action and if left unpainted remain bright but painted a white powder zinc oxide builds up and until paint no longer has a hold ,the zinc is the sacrificial part of galved steel,just looks unsightly still last decades
 
I painted my galv roofrack with hammerite 'straight to galv'. Worked ok on non-wear parts, but came off pretty quickly on the top bars where I'm sliding canoes on and off every day. It was purely for cosmetic reasons and nobody really sees the top anyway...
 

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