Anodised aluminium

[Jonathan Webb]

I have some boat windowframes (Marsh Walters, long defunct) that have areas of corrosion on them due to leaks.
These are reasonably polished/shiny but I've been reading that anodised surfaces tend to be matt and are also porous (and often dyed, but not in this case).
Does anyone know how these may have been treated and finished? If you anodise polished aluminium, I think it'll be satin finish at best? Would it then be lacquered (if so, with what? 2k is not on the menu though). Pic shows frames in better condition than mine. Many thanks.

 

[500e]

Couple of ideas shame dad is no longer with us as he ran a plating Co for a few years and specialized in alloy

Sealing of anodised aluminium and testing of sealed layer: FAQs + Q&A Forum

Sealing of anodised aluminium and testing of sealed layer

www.finishing.com

Anodising Sealing for Marine Applications? - Metal Finishings Ltd

Hard Anodising | Metal Parts | Hard Anodising Surface Treatments

Maximise durability and performance with Hard Anodising's leading hard anodising services and hard coat anodizing solutions.

www.hard-anodising.co.uk

 

[julianf]

Anodising dyes the oxide layer and then there's further treatment to harden / seal it.

@Kram has a long thread on DIY anodising.

If you sand the frame, you'll be left with a non anodised part which will not be as hard wearing.

If the anodising is gone / compromised, the best way would be to get them re-anodised.

Second best would be to sand them to remove anything soft, and epoxy primer them.

 

[Jonathan Webb]

Couple of ideas shame dad is no longer with us as he ran a plating Co for a few years and specialized in alloy

Sealing of anodised aluminium and testing of sealed layer: FAQs + Q&A Forum

Sealing of anodised aluminium and testing of sealed layer

www.finishing.com

Anodising Sealing for Marine Applications? - Metal Finishings Ltd

Hard Anodising | Metal Parts | Hard Anodising Surface Treatments

Maximise durability and performance with Hard Anodising's leading hard anodising services and hard coat anodizing solutions.

www.hard-anodising.co.uk

Thanks, I'll look at these

 

[Keith 66]

They would have been anodised when made & left natural colour, I wasnt aware that sealant or lacquer was used.
My boat had similar windows & they were too pitted locally to re anodise, So it was new ones, cost an arm & several legs!

 

[Onoff]

Have a look at Nyalic.

 

[Kram]

Anodising has an ideal rough porous surface for taking a paint or a durable finish. There are many different ways to do it while most people are only familiar with the common commerical dyed annodising.

The problem you'd have with yours, is they are huge with a large surface area, which means you need a huge container and beefy power supply, and lots of chemical to do it properly.

I think you'd be best with an acid etch 2k clear coat.

This was the previous long thread..

Annodising Aluminium

Started with the small test piece. Based on 37cm² and 6A/foot² Im running at 240mA, aluminium cathode and sulphuric acid. As this sulphuric was generated using a lead annode theres a fair bit of dissolved lead which is plating out on the cathode. I'll clean it off before I do the proper parts.

www.mig-welding.co.uk

 

[fizzy]

Thanks - a nice timely post - want to have a try myself.

 

[bricol]

I wanted some aluminium parts anodising, but not sealing, as a base for paint. Anodising bloke suggested something else prior to paint, which five years later of constant exposure is looking as good as when it was done . . . problem is, I can't remember what he suggested

 

[500e]

Never come across that @Onoff interesting

Marine Clear Coat | Clear Coat for Fiberglass & Aluminum Boats

 

[Kram]

Looks like its a 1k clearcoat?

 

[graffian]

I wanted some aluminium parts anodising, but not sealing, as a base for paint. Anodising bloke suggested something else prior to paint, which five years later of constant exposure is looking as good as when it was done . . . problem is, I can't remember what he suggested

Alodine/Anochrome or maybe that should be alochrome or anodine?
We used to get lot of parts from an outboard motor place to repair, from us they went to
the platers to be alodined and from him to the stovers to be painted.
Same with parts for the Bristows[helicopters].
But when I asked I was told anodising was a better base for paint?

Far from Crawley? take the frames to A1 anodising and have them anodised.
I always prep the parts myself, caustic to remove old anodising and polish if
you want them shiny.

 

[Morrisman]

I wanted some aluminium parts anodising, but not sealing, as a base for paint. Anodising bloke suggested something else prior to paint, which five years later of constant exposure is looking as good as when it was done . . . problem is, I can't remember what he suggested

I had some alloy bike parts beadblasted decades ago, it leaves a nice satin sort of finish. I then shot WD40 on them to stop the greasy fingerprints showing. Oddly enough they never corroded even when the bike was used through English winters. I'm not sure if the blasting beats the surface hard or seals it or what.

 

[Jonathan Webb]

Anodising dyes the oxide layer and then there's further treatment to harden / seal it.

@Kram has a long thread on DIY anodising.

If you sand the frame, you'll be left with a non anodised part which will not be as hard wearing.

If the anodising is gone / compromised, the best way would be to get them re-anodised.

Second best would be to sand them to remove anything soft, and epoxy primer them.

Thanks. Could

 

[Jonathan Webb]

...Second best would be to sand them to remove anything soft, and epoxy primer them.

I've got these out now and cleaning them up in the shed.
I'm not in a position to send them out for anodising, but I have got some PPG epoxy primer (Sigmacover 280) but no topcoat. Would the primer offer some protection on it's own? I would only paint the window channel "U" as shown in the technical drawing attached , so it'd never see any UV. My understanding is that generally, primer's purpose is to promote adhesion of the next layer but doesn't necessarily have waterproof properties but being epoxy, this might? I've looked at the PPG blurb and it's not explicit about that property AFAICT. Any thoughts? Many thanks.