Last 3 days I've been doing some trial and error home anodizing and finally got a result that worked.
Often you just want a piece of aluminium for a project that needs to be corrosion resistant, non conductive and 'pretty' with some kind of different colour. But big places don't want anything to do with hobby people and normally this involves using sulphuric acid... which is fun, but hard to get and WILL to fuck your shit up if you get it on yourself or anything else you don't want burnt and dissolved.
In my case, I just wanted a couple of bolsters done up and slapped on a knife I was making
Solution- Sodium Bisulphate which is normally found in hardware stores as PH-Down for pools and spas.
Its still nasty, it will fuck your shit up and anything it touches, but its:
>A- cheap
>B- easy to get
>C- wont put you on a terrorist watch list and can be tipped down the sink when you're done
Ratio I was using was 10 teaspoons of the powder for 250ml (1 cup) of cold tap water
Put it in a clean jar, swizz it around until its gone a cloudy colour and all the grains are dissolved
In the meantime lets get a list of stuff you need-
Distilled water- for rinsing parts
Methylated spirits/alcohol- for cleaning parts
Packet of PH-Down
Rubber gloves (clean)
Measuring cup
Saucepan
Glass Jar or acid resistant plastic bucket
Power-supply- around 6-12v and 1-2 amps (1000-2000ma)
Aluminium Wire- 4-5mm 1ft long
Aluminium wire- 2-3mm and 1ft long
Paper cloths
Non-ferrous scrubber
Old toothbrush
>>1007950
Most important is the parts prep and connection.
With your aluminium part it must be excruciatingly clean-
Gloves on
Give it a dunk in some soapy water and scrub it clean as you can
Once that's done, paper cloth and couple of drops of metho-spirit to get any final residue off it (do not touch it with bare hands!)
Dunk it in some distilled water and let it soak while you set up the rig
Connection to the piece is very important to the anodizing process so I recommend that you pin-it with a small length of aluminium wire (2-3mm) and anchor it firmly in the piece.
Dangling it off a wire looped into the solution doesn't work, the wire will anodize and become non conductive
Alternatively- you can wrap the wire around it until it is firmly held in place
In the acid tank you can only have aluminium in there, though pure lead will do for the anode end on a length of aluminium wire
Roughly the size of the anode = size of the work you're anodizing
>>1007957
Power supplies as long as they pump out some decent amperage will do the job 1-2 amps seems to be fine for small pieces, you can get them out of old laptops battery chargers, car battery chargers and various utility devices- as long as they're DC and around 6-12v = all good
The Anode I just made up out of some 5mm aluminium wire into a coil with an end poking out of the acid tank you can wrap the wire around or use an alligator clip
This is where the (-) Negative goes
The bar across the top for suspending the work pieces, same type of wire, squashed flat, couple of holes drilled into it
This is where the (+) Positive goes
When you dangle the work piece in the solution, make sure its deep enough to be covered and won't touch the (-) negative
Tiny bubbles will come off both pieces, generally this is Hydrogen in trace amounts and not really a risk, but you might also get a sulphide smell too which means get a bit of ventilation going
Run this powered up for about 60-120min or until it stops bubbling
(This is not exactly high excitement for science!)
>>1007960
Once its done its course, you can check if its properly anodized as it will have a slightly 'yellowy-oily' tinge where the surface has been altered via the process.
A slightly more blunt approach- run the -/+ wires across it, if its sparking then it didn't work, if there's no sparks = winner!
Give the part a quick rinse under COLD water then let it dry out- DON'T touch it!
Dye, you can use most water based dyes and inks, there are expensive anodizing dyes as well from Caswells which are made for this, RIT cloth dye also works but its not UV resistant.
Sharpy markers also work, I used a bottle of spirit based ink which is essentially full on sharpy marker fluid and comes in red or black, but its up to you to experiment and try what will work.
Water based dyes, give the work piece a good dunk in that for about 30min to let it soak into the piece
Spirit based dyes, seemed to take less time, take them out and let them dry
Get mums/wifeys best stainless steel saucepan because its science fuck ya, chuck some water in there and bring it to a rolling boil/good simmer, drop the piece in there (don't fucking touch it with your bare hands!) and leave it for 20-30min
>>1007963
Once its cooked, pull it out and rinse it under some cold water, give it a gentle scrub with the washing up scrubber and it 'should' have the colour embedded into the metal a couple of microns deep.
The surface of the metal is also now slightly hardened and non-conductive
Where it all goes wrong
>Solution no strong enough?
>Connection not good enough?
Those where the two areas which seemed to mess me about when I was experimenting.
It is imperative though that the work be clean, hence never touch it with bare hands (you grub) as it'll transfer dirt and oil to the piece and fuck it up with big fingerprints or streaks.
Other things
If you want a matt finish, give it a dunk in some drain cleaner (Sodium Hydroxide) for a couple of minutes on the end of its connection, rinse it off in distilled water and then plunge it into the acid solution
Have fun
Don't get this shit on yourself or you'll melt
>>1007964
Lets see that thing properly.
>>1007977
Damned if I can get the camera to focus with such little light, its a bit of a potato.
Just to amend an error earlier-
>>1007946
>10 teaspoons of the powder for 250ml (1 cup) of cold tap water
Should be 5 tsp per 250ml or roughly 10-11 per 500ml, (sorry about that)
What I did notice was that the test piece was just a 4x2.5cm slab which I chopped up, filed to shape, ran over it with 180grit and then 600 wet sandpaper and it shows up all the scratches quite well
So if you're after a shine it'd need a lot more work in getting out every single one of those, so 150/180 grit, then down to 600 and 1200 grit, maybe even 2000 grit and then hit it with the buffer and polish to make it really shiny. Surface finish seems to be pretty durable as I'd hoped though
>>1007946
Sulphuric acid is neither hard to come by or super dangerous. The only real risk is to your eyes. As long as you aren't an idiot and immediately wash it off/wear gloves and goggles/work in ventilated spaces and obviously dont leave a pool of the stuff on the floor it's not hazardous.
>>1007946
Also you can do some neat calculations with electroplating to find out exactly how much time/ current you'll need for a given object. Lookup faraday's laws of elecrolysis.
ahhh i was using stainless steel as my anode
now i shall try with an aluminium anode
no one else is interested?
op more pics
>>1008107
Depend where you are in the world, some countries restrict its sale, others (like mine) seem to have it in very niche suppliers and its not commonly available- but its horrible to try and get shipped anywhere and they'll gouge you on freight. Whereas, I can walk into any pool supply or hardware store and get 3kg of Sodium Bisulphate for about $10, its safe to transport and generally pretty easy to live with in that you can't really spill it and one of those substances I'd be happy to teach kids how to make stuff with.
>>1009546
In a sort of circular argument- using aluminium for a high end knife's bolster, I eventually kind of won that one and we're back to square one using 304 stainless steel. So the knife will be finished off with that, instead of aluminium.
Which is nice because my files, drill bits and generally shit everywhere, isn't clagged up with bloody aluminium bits! (I like alu, but it can be a shit)
Unfortunately- no finished product to show you :(
What I will do in a month or so is a run of O1 carbon steel blades and what I might do there is a quick thread on Parkerizing and possibly if I'm feeling particularly brave - hot bluing!
Both of which you can DIY with not inordinately hard to get supplies and get some pretty decent results with.
>>1009870
>Parkerizing and hot bluing thread
im down . . . as long as you take better pics
>>1009887
>I'm an engineer, not a journalist captain!
But yeah, really need daylight to get anything decent out of my little potatophone
As you can see the darker parts on the sides of the test piece where probably because of a different texture on the material, so the finish is very important
>>1009890
next time make sure to file it untill it seems smooth enough before electrolizing.
Also, you cak make it shine adding a bit of sacharyne in the solution (less than 0,1g/l)
>>1009890
Neato, thanks for sharing.
