De anodising.

[Richard.]

I've read, heard of and even carried out quite Afew methods of anodising removal on aluminium but none of them seem to quite cover what I want to do. I've got a few lengths of Alu stock which I obtained for silly low money and it's perfect for fabrication apart from the satin anodised finish. I would like to be able to remove the anodising layer(s) when I need to in the areas I wish to weld. It's not an option to soak these long lengths in a bath of chemicals but a chemical solution is preferred as I don't want to mechanically scrub it off. Is. There such a product that people have used and had results with that's easily obtainable, not stupidly expensive that I can put on the areas I need it and let it do its thing then wipe clean and weld. I'm asking a lot mind but if this proves successful I'm on to a winner as this aluminium is available as much as I want and I can change suppliers. I'd rather not remove all of it if possible as the satin hard finish looks pretty nice on finished product. Only where the welding will be placed.

 

[eSCHEn]

Spot treatment with caustic soda?

You can use CS to clean off old anodising, here's a great source of anodising information for DIY.

 

[rikrobson]

do you not use electrolysis to remove it? thats how it was put on in the first place.

 

[Richard.]

Spot treatment with caustic soda?

You can use CS to clean off old anodising, here's a great source of anodising information for DIY.

I've read this and it describes how to do it in a bath. Not so practical on 2-3 mtr lengths where I want to remove it in certain areas. Will caustic soda work if applied locally

 

[rikrobson]

I found this on a site about anodising ally

Fizz the aluminium in caustic soda solution until it looks a nice grey colour. If the aluminium is already anodized, it is possible to remove the anodized layer by leaving it in the caustic soda bath for longer. I've not read of the correct strength of the caustic soda bath for preparing the metal. An eggcup or two of caustic soda granules in a pint of warm water works for me.

 

[eSCHEn]

I've read this and it describes how to do it in a bath. Not so practical on 2-3 mtr lengths where I want to remove it in certain areas. Will caustic soda work if applied locally

I think it will depend on the length of time required to do take the surface to the condition you require. If it's quick the yes, just paint it on (possibly you could thicken it with cornflower or something else mucilaginous?) and then rinse off when done. For longer exposures you could slowly trickle a jug full on the area and collect in a bucket underneath.

Never done it myself so YMMV.

 

[Richard.]

It's fairly thick coating. I filed a bit off last night which was easy enough. It's lovely to weld when removed. Id imagine it would take a bit of time to eat through it but that's no issue to me so Long as it does what I want.

 

[Richard.]

I found this on a site about anodising ally

Fizz the aluminium in caustic soda solution until it looks a nice grey colour. If the aluminium is already anodized, it is possible to remove the anodized layer by leaving it in the caustic soda bath for longer. I've not read of the correct strength of the caustic soda bath for preparing the metal. An eggcup or two of caustic soda granules in a pint of warm water works for me.

It cannot be done in a bath. These are 2 and 3 mtr long. I want something that can be applied to the area(s) I wish to weld on and removed and the area is ready for a stitch.

 

[PSweeney]

a strong over cleaner takes it off. Failing that a scotch brite disc on an air die grinder.

 

[Richard.]

a strong over cleaner takes it off. Failing that a scotch brite disc on an air die grinder.

Could I just spray the oven cleaner where I wanted to remove it or would it all need soaking in it to be effective. Any particular brands that work well. I've heard of easy off in the states been the desired product. What's the uk got that's equivalent.

 

[PSweeney]

think it's pot luck really, I used a Mr Muscle one years ago and it was OK, left a feint colour staining. Maybe find out what the caustic ingredient is and buy one with the highest content ?

 

[Maker]

Maybe find out what the caustic ingredient is and buy one with the highest content ?

Caustic huh? Would it be possible to make a paste of sodium hydroxide?

 

[Wendelspanswick]

What sort of width is it, could you drop it into a length of waste pipe or even soil pipe.

 

[Richard.]

What sort of width is it, could you drop it into a length of waste pipe or even soil pipe.

Thing is I don't want to remove any more than I need to in order to weld it. Looks like it might be a mechanical removal.

 

[DecK]

This any help,
http://gaterosplating.co.uk/Anodise-Stripper-and-Etch.php

Don't know why that didn't link right. I get the feeling as well that's its a kg of caustic soda and a bucket for a tenner

Edit: I was thinking apply with a paint brush a few times to the area and wash off. Could be way off the mark though

 

[Rrunnach]

When I was an apprentice and work got slack, we would get chucked into anodizing area. Aweful yet interesting work. If a particular job was not fully processed, back into caustic soda (which was hot) bath for a thorough etch, then back through the other baths.

 

[wilbur]

There's a paint stripper called, I think, 'Peel-away', which I've used (think it came from Decorating Direct) - that has a caustic paste with a plastic sheet you press into it - after leaving it for a while you peel the whole thing off: sheet, paste and paint. I've no idea if it removes anodising, but it would be easy enough to use for small areas if it did. I seem to remember it came with some kind of acidic neutraliser and a book of indicator paper to test the pH of the surface afterwards, which made it all seem particularly fun and exciting. At least by the standards of paint removal, anyway.

Update - looks like it's been replaced: http://www.decoratingdirect.co.uk/viewprod/p/PALPA1/

 

[Richard.]

There's a paint stripper called, I think, 'Peel-away', which I've used (think it came from Decorating Direct) - that has a caustic paste with a plastic sheet you press into it - after leaving it for a while you peel the whole thing off: sheet, paste and paint. I've no idea if it removes anodising, but it would be easy enough to use for small areas if it did. I seem to remember it came with some kind of acidic neutraliser and a book of indicator paper to test the pH of the surface afterwards, which made it all seem particularly fun and exciting. At least by the standards of paint removal, anyway.

Update - looks like it's been replaced: http://www.decoratingdirect.co.uk/viewprod/p/PALPA1/

Now that's interesting info. Cheers mate.

 

[AndersK]

I have mixed caustic soda with wallpaper glue (powder type that is mixed with water) to get a paste for paint removal.

Should work for this too.