# Sulfuric Acid source for Anodizing Aluminum?



## VanIsleDSM (Apr 12, 2008)

*DIY Aluminum Anodizing: where to purchase lye?*

I found one place online... but over $20 for 250ml ! A better price for the 500ml.. but still quite steep.

http://www.chemical-supermarket.com...0ml-p30.html?gclid=CJCM2c6C1ZICFQwwiQod5Q-P6Q

you mix is 5:1 with water apparently.. so with 6 parts in total I could have 1.5 liters.. I think I'd have to go with 500ml for 3 liters to have a decent tank.

I've heard battery acid can be used too.. but being somewhat diluted already you only mix it 1:1.. but I'm not certain on that... maybe a battery acid source would be much cheaper.. but no luck on that so far.

On a side note.. I've heard of people using computer power supplies @ 12v, but commercial anodizing is done at higher voltage.. I think I'll use a laptop PSU around 19v... and unable to think of a source of lead sheet for the cathode, I plan to get a big fishing weight and beat it flat.


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## LukeA (Apr 12, 2008)

Why not just use some sheets from inside the lead-acid battery you're going to get the acid from?

Edit: fishersci.com has a liter of concentrated sulfuric acid for $31, but I definitely wouldn't want any concentrated sulfuric acid just sitting around at all. On the DOT 1-8 scale of material hazard, it's an 8. Fisher also has less concentrated acid.

I'm not sure where chemical supermarket gets off saying it has an odor, everywhere else says odorless, and I've never noticed any odor, but we only ever used 1M.


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## gojira54 (Apr 12, 2008)

I'm an M&E engineer and have done some anodizing at home as I was able to get some acid from work. Some commercial swimming pools use 45% concentrated acid in the dosing system, you could try a pool supplier near you :0)


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## BIGIRON (Apr 12, 2008)

Will muriatic acid solution (20% hydrochloric) from Home Depot work? It's $3 or $4 per gallon.


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## VegasF6 (Apr 12, 2008)

I am sure you have seen this page.
http://www.focuser.com/atm/anodize/anodize.html
He also mentions battery acid. His other supplies he only ships to the US so if you needed them it would be a problem, but I guess you have everything else. For the brief second when I thought I might try some of this I had in mind a big roll away battery charger of mine. Probably overkill but would have power to spare.


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## Illum (Apr 12, 2008)

http://www.enasco.com/product/KM01053M
yeah....500ml for $15oo:
H2S04, 95% conc. made from ACS-grade sulfuric acid.


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## tvodrd (Apr 12, 2008)

For amateur plating/anodizing, consider Caswell.

:Larry


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## VanIsleDSM (Apr 15, 2008)

Thanks for the suggestions.. definitely have some better options now.. I'm just going to check on the shipping for this stuff.. which might be extra because of the contents? ..and also check napa, where I can apparently get battery acid... time to weigh my options and start anodizing


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## VanIsleDSM (Apr 28, 2008)

OK.. just an update and another question I figure I'll throw in here rather than start another thread...

Seems Napa is the best place to go for price. You can get a 5 gallon bucket of battery acid for $30.

..However I've hit a bit of a road block. I tried to order some aluminum wire from Mcmaster-Carr but got an email back from them a few days later saying that they won't ship to Canada any more... because of "tightening US export laws" ..what a crock of crap that is. The terrorists are winning damnit, I can't even order aluminum wire... everyone needs to stop being so paranoid.

Anyway.. on to my question.. Since I can't order some aluminum wire from them.. I was thinking, what about using some aluminum MIG welding wire? Only I'm not sure what else they put into the alloy for welding.. but I suppose I'll try it out, dunno where else to get any aluminum wire. You guys think that'll work fine?


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## Norm (Apr 28, 2008)

Just a thought, If you see a power crew working in the street, ask them for some aluminium wire, I know our power wires here in Australia are mostly aluminium, I'm sure they would mind giving you some scrap. You might even be able to call around to their depot.
Norm


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## LukeA (Apr 28, 2008)

VanIsleDSM said:


> OK.. just an update and another question I figure I'll throw in here rather than start another thread...
> 
> Seems Napa is the best place to go for price. You can get a 5 gallon bucket of battery acid for $30.
> 
> ...



Does onlinemetals.com ship to Canada?


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## Tekno_Cowboy (May 24, 2008)

Rooto can be picked up at most hardware stores. Ace Hardware generally carries several types of concentrated acid. Try a professional carwash.


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## VanIsleDSM (Jul 2, 2008)

Ok, I've come pretty far with this, I'm pretty much ready, here's my quick hacked up anodizing tank completely with a little rack for hanging wire and a gigantic cathode to make sure I do a good job on the high surface area heatsinks I'll be anodizing. I made it so the lid could fit back on as well.







Beside you can see my 30 liter bag of battery acid I got for $30 at Napa. I also have some deionized distilled water to which I will add the acid 50/50, since battery acid is 35/65 acid/water and you're goal is 15-20% acid for the anodizing mixture.

Now I just need to get some lye so I can prep the aluminum before anodizing it. I haven't been able to find any locally.. seems to be a bit online, but shipping is steep because of the weight. I know it's used for soap making, and anyone that's been around my part of the world, especially the Gulf Islands, would know, there are definitely a lot of soap maker types around here..  But I imagine they'd be hardcore enough to brew their own lye from wood ash as well.

I'm going to just get out the phone book tomorrow and call anywhere I think might have some lye. Anybody have any suggestions? know any other uses for it that would give me other ideas of where to look locally?

I'll keep updating, can't wait to anodize my first piece


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## TOOCOOL (Jul 2, 2008)

*Drāno* has a lot of lye in it would that work ?


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## LukeA (Jul 2, 2008)

Biodiesel suppliers, and it's in drain cleaner and oven cleaner. If you have any Scandinavian churches/restaurants, they use lye to make lutefisk.


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## mahoney (Jul 2, 2008)

If you have not solved the aluminium wire problem yet, the most common alloy of MIG welding wire available is ER-4043, but ER-1100 (pure aluminium) is also available.


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## Fenris (Jul 2, 2008)

Go to just about any store(grocery, hardware) and ask for Red Devil Lye.

Be careful with caustics. You can get burned very badly before you even feel it. Lye will start to breakdown fat cells on contact and essentially turn them into soap.


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## matrixshaman (Jul 2, 2008)

Are you planning on doing any color anodizing or just natural?


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## VanIsleDSM (Jul 3, 2008)

Red Devil is discontinued now.

I've checked the hardware stores, but not grocery stores yet.. I'll give that a whirl.

I plan to do mostly natural anodizing, but I'll be trying some colours too.


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## FredM (Jul 3, 2008)

Most universities have a research store that sells all kinds of stuff. I think we just paid 18 bucks for a 2.5L of 18 molar.


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## Cookie Monster (Jul 5, 2008)

tvodrd said:


> For amateur plating/anodizing, consider Caswell.
> 
> :Larry


 
:thanks: for the tip... I've been thinking of giving anodizing a try.


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## Oznog (Jul 5, 2008)

Draino is not useful. Draino is more than just sodium hydroxide.

What you need is called RED DEVIL LYE. It's sold as drain cleaner and it's just that, 100% sodium hydroxide in all its nasty chemical goodness.

You can get sulfuric acid (and nothing else) as drain cleaner at a few hardware stores. The concentration is pretty strong. It's very unusual, just one product in an aisle of alkaline products. At least you used to be able to get it, I haven't tried to buy any in a few years. They actually bag the bottle in a heat sealed bag.


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## Oznog (Jul 6, 2008)

What does anodization (with dye colors) do to the thermal conductivity in the LED-to-sink interface? What does it do to the heatsink-to-air conductivity?


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## VanIsleDSM (Jul 7, 2008)

I'm not sure about heat transfer, the layer is so microscopically thin though, that I doubt it would make any difference. Anodizing does however increase surface emissivity of heat by about 70-80%, which will make quite a large difference for any passive heatsink.

Unfortunately red devil lye has been discontinued. Apparently some people were using it to make meth. Well good job there boys, I'm sure taking it off the market will completely stop the meth problem.. I'm sure getting ahold of lye is the meth-makers biggest hurdle :shakehead


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## iq2k (Jul 23, 2008)

lye is basically caustic soda, drain cleaner, also used for making soap & candles etc.
But of all it's uses i think as drain cleaner will be the cheapest source.
to get it i would suggest to traul though the hardware shops theres plenty of caustic soda out there & cheap.


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## davidt (Jul 23, 2008)

Try ace hardware store. I bought some sulfuric acid there as drain cleaner, although it was about 2 years ago. It was some pretty high quality stuff. Completly clear with a hint of yellow. I estimate the concentration to be at least 90%. I think it was 5 dollars for 1 quart.

Ace hardware also sells pure lye when I went there to purchase acid. I saw some 1 pound containers. I checked the ace website, but it was only listed as 48 dollars for 12 containers.

I know home depot sells pure lye. I think 1 pound for 7 bucks. The lye is roebic brand.


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## Tekno_Cowboy (Jul 24, 2008)

davidt said:


> Try ace hardware store. I bought some sulfuric acid there as drain cleaner, although it was about 2 years ago. It was some pretty high quality stuff. Completly clear with a hint of yellow. I estimate the concentration to be at least 90%. I think it was 5 dollars for 1 quart.
> 
> Ace hardware also sells pure lye when I went there to purchase acid. I saw some 1 pound containers. I checked the ace website, but it was only listed as 48 dollars for 12 containers.
> 
> I know home depot sells pure lye. I think 1 pound for 7 bucks. The lye is roebic brand.



I used to work at an Ace Hardware. I can't believe I forgot that they carry and can order acids and such. I'll talk to my former boss and see if I can get a list of what they normally carry.


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## VanIsleDSM (Jul 24, 2008)

No Ace here, but do have Home Depot, last I was there nobody working there knew what lye was. Now that I have a brand name they carry I'm sure one of them will be able to figure it out.. Thanks davidt.


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## HarryN (Jul 25, 2008)

Are you sure you need lye ? If it is for degreasing, I would use pharmacy grade 90 % rubbing alcohol. (not paint store grade)

If it is for removal of surface oxide, that is somewhat different, but it might be possible with HCl.

If you really need NaOH, it can easily be produced by looking at wikipedia, and recognizing that sodium carbonate is baking powder, and sodium bicarbonate is baking soda. If this makes sense to you, then you will know how to do this safely, if not, please don't ask as I will not tell you for obvious reasons. Sorry.

A traditional use of lye was to stunt the growth of horns on cattle - not sure if that is still true or not. This would imply that farm supply stores might have it.

IIRC, you can get harder / denser surfaces if you can keep the sulfuric concentrated and cold. This is part of the hard anodizing process, but does not dye very well.


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## VanIsleDSM (Jul 30, 2008)

Alright.. I've got everything together now and I anodized my first piece of scrap today.. turned out amazing! I just used some green food dye for this piece.. mostly I'll just be doing natural finishes for protection and better heat emissivity, but I was surprised as how well the food die worked.







After some more practice I might set up an anodizing service for CPF.. now to work on a nice power supply for the tank, along with a cooling system so I can start doing HA at home


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## VanIsleDSM (Jul 31, 2008)

Just tried some red. I left it in the dye for quite a while to make sure that it didn't come out pink. No worries of that.. it's quite dark, almost maroon. If I would have done this with the green it would have come out a very dark forest type green. I'm extremely satisfied with the results. Now to set up some procedures for different colours so I can be consistent..


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## Oznog (Aug 1, 2008)

VanIsleDSM said:


> ..However I've hit a bit of a road block. I tried to order some aluminum wire from Mcmaster-Carr but got an email back from them a few days later saying that they won't ship to Canada any more... because of "tightening US export laws" ..what a crock of crap that is. The terrorists are winning damnit, I can't even order aluminum wire... everyone needs to stop being so paranoid.



Damn straight... filthy Canadians, taking all our aluminum wire, for god-only-knows what purpose.

... WTF, why restrict aluminum wire?? And small quantities nonetheless. I mean if you were gonna string some cable then McMaC is about the most expensive place possible to do it.

Anyhow, for a real question, where's the best place to get dyes? I do wanna try some anodizing.
I have an adjustable power supply that can put out 6 amps. So if my part is of sufficient sq footage that I can't get 8 amps/sq ft mentioned as a minimum, will it just take longer or will it yield undesirable results as the acid attacks the aluminum surface faster than the anodization passivates the surface?


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## VanIsleDSM (Aug 1, 2008)

So far I haven't paid attention to the amp/sqft rule.. I've just been running 12V through. Something I notice though, when you first hook up the power there's a huge surge of energy.. Last night it kept setting off the short circuit protection on the power supply when I was trying to do a small little single cell flashlight.. and then quickly dropped to about 800mA... but to get it to even start I grabbed some nichrome wire close by, and ran the wire up the nichrome as I plugged it in, quite a maneuver, to increase the resistance at first so I didn't trip the short circuit protection again. So.. for anyone making an anodizing tank, I would add "large capacitor" to your parts list, unless your PSU is built for huge initial current surges.

For dye I've just been using food colouring, I've heard everyone say RIT is great.. but I can't imagine better results than I've seen with the food colouring.. now I just need to find somewhere to get it in bulk.


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## mahoney (Aug 1, 2008)

I've seen pint and/or quart bottles of food coloring at local "cash and carry" type restaurant and bakers supply places. RIT might be a little easier to find at sewing and craft suppliers. Be careful with it, there's some evidence that certain dyes can cause cancer


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## VanIsleDSM (Aug 6, 2008)

Thanks mahoney, I'll have to go on the hunt for some, on the meantime my small make-do dye tanks are working very well.

More anodized eye candy... I love this stuff.






I'm going to try doing some custom designs anodizing aswell, fades, splashes, and a couple other ideas of my own I'd like to try.


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## jhanko (Aug 6, 2008)

Those parts look fantastic. Good job! I do have one question though. Is this somenthing that can be done inside a home or are the fumes too strong? Thanks,

Jeff


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## VanIsleDSM (Aug 8, 2008)

Thanks JHanko, I'm pretty ecstatic myself, can't believe how well it's all worked..

As for the fumes.. You're performing electrolysis, and there are bubbles.. so there must be fumes, of what? I'm not too sure, some chemistry buff could probably figure that out. There's a kind of mist of acid too.. so use a lid. So far I've just done it outside, but I'm going to put the tank into a sealed box and use an exhaust fan to blow outside when I move it in the garage.


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## HarryN (Aug 9, 2008)

There bubbles are H2 and the fumes are sulfuric acid mist. It is very much not an indoor / in the house activity.

In the garage, you might be able to tolerate the fumes and slight corrosion of your tools, but a fan / exhaust is a real must. 

Nice work BTW. :wave:


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