Alloy corrosion

[Kenneth DeightonParticipant @kennethdeighton43272]

[Kenneth DeightonParticipant @kennethdeighton43272]

I am restoring a pair of garden lamps, the alloy castings are very corroded, what treatment should I give them before I paint them? Ken.

[Gray62Participant @gray62]

depends on how bad the corrosion is, but, if you want to restore a smooth finish, then I would suggest using a flexible car body filler such as P38 or U-Pol. Both are easy to sand to shape and will bond well to alloy castings.

CB

[Sub MandrelParticipant @submandrel]

Hi Ken,

If they are whitemetal castings with a white powdery bloom, this could be tin oxide. Tin oxide catalyses its own spread so it's a good idea to get as much off as you can with a stiff wire brush then use zinc oxide primer before painting.

Neil

[Kenneth DeightonParticipant @kennethdeighton43272]

Thankyou for your thoughts , it is a "chemical " solution that I was looking for such as Jenolite, as the finnish need not be as good as body work etc as they will only be in the garden.

[KWILParticipant @kwil]

Shot blast them and paint immediately before the dreaded white powder comes back.

[Peter TuckerParticipant @petertucker86088]

Hi Kenneth,

If the corrosion is bad I would recommend you whip up a model and re cast the fittings.

Peter.

[thomas oliver 2Participant @thomasoliver2]

I would be interested to know how tin oxide would form on alloy castings. Alloy cleaner for car wheels can be obtained at autospare shops. I have a 6in powered wire wheel which is very efficient for such work. It is good on paint jobs as well. Tomol.

[Sub MandrelParticipant @submandrel]

Hi Thomas,

'alloy' mean any mixture of metals, not just aluminium and magnesium alloys isued for car parts. I have some garden 'coach style' lamps and they appear to be 'white metal' – name for a wide range of low melting point alloys that are mostly tin with varying amounts of lead, copper antimony and other metals. Think Dinky/Matchbox cars (at least the old ones, I expect the new ones are lead free).

As Peter suggest the melting point is usually low enough that they can be easily melted with a blowlamp.

Neil

[Deltic007Participant @deltic007]

I would lightly blast off and apply a good etch primer straightaway then either powder coat of wet spray and make sure you get over 300 microns of paint or powder on.

Mike

[Deltic007Participant @deltic007]

I would lightly blast off and apply a good etch primer straightaway then either powder coat of wet spray and make sure you get over 300 microns of paint or powder on.

Mike

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