<willie.macleod@gmail.com> wrote in message
news:1134421557.414377.313920@g14g2000cwa.googlegr oups.com...
> Austin Shackles wrote:
>
> > From what I gather, hot-dip galv is apt to give you a distorted
bulkhead.
>
> If you have a firm who don't know what they're doing having only
done
> things like posts of thick steel and the like then chances are
you're
> going to end up with a rather hard to fit bulkhead, yes. Not the
case
> with the one I had done though, and I've seen plenty others.
>
> > Presumably the electroplating method is OK though.
>
> That's different again! From the talk of bead blasting I assumed
> Andrew meant hot zinc spraying, rather similar to hot dip
galvanising
> than electroplating.
>
> For the chap asking about Galavafroid, I did a series II rear
cappings
> with that and it's petrol cap and it wore through/off in places in
less
> than two years. Looks very dull as well, doesn't age that nicely
> compared to real galv, but then that vehicle does live on the North
> East coast and there is a lot of salt on the road compared to other
> parts of the UK.
>
> Regards
>
> William MacLeod
>


When they 'hot spray' with a Metco gun the part infact only gets
barely warm - the zinc impacts on the newly bead blasted surface and
forms small interlocking 'cowpats' that mechanically bond onto the
slightly roughened surface. I have a rather old Metco gun (maybe
1960's) that uses oxy-acetylene as the heat source and compressed air
to drive a turbine that pulls an 1/8" zinc wire through the flame. You
can actually spray zinc onto wood, and form an apparently solid
surface without charring the wood.

AWEM

"Andrew Mawson" <andrew@no_spam_please_mawson.org.uk> wrote in message
news:dnkpo5$s71$1@nwrdmz02.dmz.ncs.ea.ibs-infra.bt.com...
>
> <willie.macleod@gmail.com> wrote in message
> news:1134388865.547130.242720@f14g2000cwb.googlegr oups.com...
> > fanie wrote:
> >
> > > Get it galvanized
> >
> > Seconded - it's harder to get a decent paint finish onto it with
> galv
> > but if you can find a local firm who have a bit of skill galvanising
> > (and that bit is important!) then there's little will match galv,
> > filling with warm waxoyl and a couple of coats of paint.
> >
> > Zinc spraying is a probably less risky process (never had it done on
> > anything) but not so effective in protecting the inside of the
> > bulkhead, I take it Andrew is talking about hot spray as opposed to
> > Galavafroid or similar.
> >
> > Regards
> >
> > William MacLeod
> >
>
> Absolutely. Had my trailer done 10 years ago with a Metco zinc spray
> gun and it's stood up to alsorts of misuse very well.
>
> AWEM
>
>
Ok so who can recomend a firm that knows what they are doing to gavlanise my
bulkhead without distorting it.

I based in Northamptonshire.

Gerald

They are all doomed, I tell you, doomed.


--
Larry
Series 3 rust and holes


"Idris" <Idris@daviesrus.f2s.com> wrote in message
news:dngu8a$2a0$1@news.freedom2surf.net...
> Ive brought a new bulkhead, its in the bare black primer, what do I paint
it
> with to prevent it rusting like the old one?
>
> Do I treat areas on show and the underside differently?
>
> Regards
>
> Gerald
>
>

I' ve had stuff hot zinc sprayed, and is ideal for heavy lumps. We used it on wiches for fishing boats and the loading cranes. Once the rust has been grit blasted off(rather severely), the hot zinc powder is melted as it's sprayed. We also do it with nickel now for building up the wear pads on oil drilling tools.

Due to the grit blasting, thin components are not best suited to this. The finish can be as rough as hot dip galvanising, and usually granular - which is an ideal key for thick paint.

Hot dip galvanising can have drawbacks on complicated sections. Box sections can't be effectively cleaned, and if rusty the zinc will just avoid it. Also air pockets form and usually in the worst places - corners and welds. As it is a hot process, distortion is a problem unless you make a frame jig.

The Electroplaters I've been to offer tin-zinc which gives a bright finish. The tin acts to make the zinc less available to atmospheric corrosion,so remains brighter and lasts longer. This method has problems on concave or box sections, as the charged particles of zinc are attracted to the nearest object - so edges get a thicker coat, and hollows and corners get the mimimim. Passivation is important as it again increases the resistance to oxidisation.

Ideally I'd love it to be grit blasted, then tin-zinc electroplate, and chromate passivated. Sprayed externally with an etch primer and 2 pack colour, and internally a coat of black waxoyl. - Should last for 100 years !