painted port frames

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Paddydog`1

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My painted aluminium port hole frames are beginning to show their age. The portholes themselves are and always have been completelt watertight
so I dont want to remove them if poss. Can I just sand them down,mask them off and paint with fortress special mtal primer and then a top coat?
Thanks
 
I haven't done any in situ as you're suggesting, but I have refurbished some windows using zinc chromate primer (www.lasaero.co.uk) followed by some car wheel paint from Halfords. A quick de-grease with a weak caustic soda wash before painting helps to make sure the aluminium is clean.
The zinc chromate and the caustic soda are both a bit nasty, so you might want to use a mask, rubber gloves etc.
Also used the same method when refurbishing other aluminium bits - mast fittings, furling gear etc, and the finish seems to last very well.
 
I had some done by one of our coatings technologists in the paint testing laboratory where I used to work.

Grit basted with a soft grit to avoid further damage to the metal while removing all the oxide, even in the pits

Then etch primer followed by chlorinated rubber paint.

That was a good few years ago
Etch primers now seem to have been replaced by epoxy "primers".
I'm not sure if they are technically better or simply replace for H&S reasons
 
You don't say whether they are fabricated or castings. Whatever you do with them in situ will never remove the source of corrosion and you will almost certainly find it creping in from the edges in a few years. Best is to take them out, remove all the glass and have them blasted, epoxy primer and powder coated.
 
Completely agree with Tranona; if having trouble finding people to do powder coating, motorbike shops might be able to help, especially those who customise 'bikes.

Another option is Dulux 'Metalshield' paint, it's the best stuff I have ever tried ( and I've tried most ! ); it's one-pot stuff, but does require its' own 1 - part primer; used it on the alloy tracks my rubbing strake is fitted to, also my steel keel; about £20 a tin, available from Brewers paints etc.

No connection.

My alloy window frames are OK but I had to replace the perspex; the fastenings are some special job unlike I've ever seen elsewhere, so if you think you may have something similar, don't drop or lose them !
 
srp said:
The zinc chromate and the caustic soda are both a bit nasty, so you might want to use a mask, rubber gloves etc.
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Dont know about the chromate but the caustic soda is more than a "bit nasty". It will dissolve flesh. In fact if you ever decide to do away with swmbo, its a good way of dissolving the body and flushing down the drain. I am not speaking from personal experience! :eek:

So do take real care using it. And mix the solid caustic with the water in the correct way because of the heat generated when dissolving can cause spitting and localised boiling

And dont treat this warning like all the other half baked H&S type sermons we all receive. It really is nasty
 
Seajet said:
Completely agree with Tranona; if having trouble finding people to do powder coating, motorbike shops might be able to help, especially those who customise 'bikes.
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No problem getting that sort of work done in Poole. Blaster and powder coating about 100 yards apart less than 2 miles from home - and a stainless fabricator a mile the other way etc etc.
 
Personally I always add the caustic soda crystals to water. That way the solution starts off as being more dilute, increasing in strength as the crystals are added. Same applies to acid - add acid to water, not the other way round as it will spit dangerously.
I always hesitate to preach H and S instructions on here - following an ambulance job in my boatyard I happened to mention once that it was a good idea to tie your ladder to the boat, and it was met with howls of protest from someone who thought I was stupid for mentioning it. Takes all sorts I suppose. Anyway, I mentioned rubber gloves and being careful. I also have a bucket of clean cold water handy for immediate rinsing. The fumes from a freshly mixed solution are also nasty, so take steps to avoid them. DYOR, as they say (in this case the COSHH data sheets).
 
About 8 years ago I decided to rebuild my 25 year old ally mast , looking around at other painted masts I was worried about how robust the paint finish would be.The old finish was gold anodised that was wearing through to silver , I decided to go with a system from Epifanes as I was confident about their past products . They said if the mast is new and anodised give it a wash then spray or brush their AQ one pot wash primer this goes on white and dries clear, it is a type of resin. I actually had my mast finely abraded as I was unhappy with the worn surface . For the second coat I used their twin pack epoxy based zinc phosphate anti corrosive primer ,I had this professionally sprayed and the paint is quite thick and covered quite a lot of imperfections. After these 2 coats I used 2 more coats of a normal twin pack white polyester . Prior to painting I did remove all the rivets etc so the result was to me spectacular and the main thing 8 years on the paint has not come off . The paint did cost over £200 but the mast is 43 ft . The cost of 500 ml or AQ wash primer is around £26 so with the epoxy anti corrosive primer and top coat it is getting towards £100 for your job but properly applied you will only do it once and I dont think you have to remove the frames if you can do a good job of prepping and masking.
 
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