# First attempt at home anodizing



## SEK_22Hornet (Feb 23, 2014)

Spent a little time today trying my hand at anodizing.  I had made a couple plates to help hold a poly AR15 80% lower while milling it out and thought I would see if I could anodize them.  I had picked up some drain cleaner to etch the parts with and some pool PH reducer (Sodium Bisulphate) for the electrolyte.  I found a piece of .062 aluminum sheet that i bent into an L shape for the cathode. I used an ice cream pail (small square one) as my anodizing tank.  I mixed the PH reducer with water (just used plain tap water for now) and put the parts into a small plastic container with some water and drain cleaner in to etch.  Used a 2 liter pop bottle to mix the electrolyte in and mixed as much as i could get to dissolve in warm tap water. Took the parts out of the etch and rinsed them, and hung one on a small piece of aluminum wire. I used an HP lab power supply so I could control the voltage and current.  After a couple attempts, I found that for my small parts, I needed to run about 600 ma at around 10 volts into the parts for about an hour, then rinse in cold water and put into a dye made with RIT liquid dye in warm water for about 5 minutes or so, then rinse and into a pan of boiling water. I need to get some heavier wire and some distilled water, but the results were very promising.  Here are the two parts after I finished:


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## mattthemuppet2 (Feb 23, 2014)

Great job! That's something I'd like to learn at some point. I'm pretty sure there are calculators that you can use that calculate voltage, amps and time from the surface area of the part. A bunch of guys I know that make bike lights do it. Some of them also seal in the dye by raising the temp slowly to boiling before taking it out and finding as that helps prevent leaching.


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## Ray C (Feb 23, 2014)

Good Job...

I bought a kit and did it a handful of times but, I just didn't like having warm buckets of H2SO4 in the shop.

Ray


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## SEK_22Hornet (Feb 23, 2014)

mattthemuppet said:


> Great job! That's something I'd like to learn at some point. I'm pretty sure there are calculators that you can use that calculate voltage, amps and time from the surface area of the part. A bunch of guys I know that make bike lights do it. Some of them also seal in the dye by raising the temp slowly to boiling before taking it out and finding as that helps prevent leaching.



Thanks! I actually saw one posted on this site - need to download it and check it out.  I'm keeping it small.  Tried the Sodium Bisulphate rather than the battery acid route since I felt it would be less hazardous. Pretty pleased with the results for a first try. I wondered if a person could use the dye to seal the part as well by just raising the temp.


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## Si Edwards (Feb 24, 2014)

That looks quite impressive for a first try. 

What type of dye is RIT, as I don't think I've ever come across that down here in Oz?

Cheers,

Si.


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## chuckorlando (Feb 24, 2014)

Nice. I'm gonna have to try this at some point


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## SEK_22Hornet (Feb 24, 2014)

Si Edwards said:


> That looks quite impressive for a first try.
> 
> What type of dye is RIT, as I don't think I've ever come across that down here in Oz?
> 
> ...



RIT is a brand of dye sold here in the US for dying cloth and clothing - commonly available at grocery stores here. Usually sold as powder to mix with water, they do have a few colors available now in a liquid concentrate form.


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## David Kirtley (Feb 24, 2014)

Makes me feel good to see it work so well. I have all the same stuff but have not gotten around to trying it yet. That and one of the cheap Craftsman powder coating kits.

Maybe if I finished more stuff, I would get to them.


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## itsme_Bernie (Feb 24, 2014)

Wow no way!!  How cool is that??  I have been interested in that for a while now, as I purchased the Caswell book on Ebay ages ago, but never had it at the front of my priority list before.  But this sounds so do-able!  



Bernie


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## Gerritt (Feb 24, 2014)

I dye fishing line with RIT, use the result to add details to plastic models. Adding vinegar sets the dye in nylon as it does with cloth as well.

No idea though how that would react chemically with what you are using. Chemistry class was 45 years ago!

Gerrit


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## Si Edwards (Feb 25, 2014)

SEK_22Hornet said:


> RIT is a brand of dye sold here in the US for dying cloth and clothing - commonly available at grocery stores here. Usually sold as powder to mix with water, they do have a few colors available now in a liquid concentrate form.



Oh! Thanks I was expecting it might have been something more exotic. This makes your results even more impressive IMHO. I'm sure I can find an equivalent clothes dye here in OZ.

thanks,

Si.


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## Walltoddj (Feb 25, 2014)

As soon as warmer weather gets here I've got to start playing with Anodizing, I've got the buckets, the DC power supply, heater for the dye, and the acid. Here is the calculator you wanted.

Todd


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## Gerritt (Feb 25, 2014)

An online version: http://www.caswellplating.com/720.html

Gerrit


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## SEK_22Hornet (Feb 28, 2014)

Really need good ventilation when doing this - the fumes from etching the aluminum in drain cleaner (lye) must be ammonia (can be pretty strong) and not sure what the plating process lets off, but there is a definite toxic odor to that as well, even with the pool chemicals for electrolyte.


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## Chucketn (Feb 28, 2014)

Walltoddj said:


> As soon as warmer weather gets here I've got to start playing with Anodizing, I've got the buckets, the DC power supply, heater for the dye, and the acid. Here is the calculator you wanted.
> 
> Todd



Todd, let me and John know when you try this. I'm sure we'd want to see it...

Chuck


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## Baithog (Feb 28, 2014)

The gas produced from reacting Aluminum with Sodium Hydroxide (lye) is Hydrogen. It is the same gas released when charging lead acid batteries. Hydrogen is explosive in very low concentrations. This is something you do not want to play with in an enclosed space, or in the presence of an ignition source. Granted, you are not generating a whole lot of the stuff, but there is always a chance of an exciting trip to the ER. I wouldn't do it in my garage. I have been tempted to try my hand with it outside, and with proper safety precautions.

Nice looking parts.


Larry


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## brino (Mar 1, 2014)

Those results are very encouraging.
I've been wanting to try this for years, but haven't got to it so far.

Now I need to go get those chemicals, dyes, etc and keep another tank and power supply in the shop.
I just tried electrolysis for rust removal on some small steel  milling machine parts as proof of concept.
That went well, but I need more time to experiment with the variables.

So many interesting projects, so little shop time.......

Dan, Thanks for sharing!

brino


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## Walltoddj (Mar 1, 2014)

Was on Caswell site today figure about $175 in supplies but that's with their dye sample pack and blackening for my steel. Good deal on shipping only $15 compared to EPI at $55 for just the blackening. I'll have to make sure I get all that I need in one shipment.

Todd


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## SEK_22Hornet (Mar 2, 2014)

What I used all came from Walmart. about $8 for the swimming pool pH reducer, About $3 for the dye, and about $5 for the drain cleaner. I mixed up a 2 liter bottle of electolyte and used maybe 1/2 cup of the pH reducer. I figured I'd start small and see if it worked. Already have several regulated power supplies, being an electronics hobbyist and Ham.  If I get serious, I may spend some money on better supplies, tanks, etc.


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## Walltoddj (Mar 2, 2014)

SEK_22Hornet said:


> What I used all came from Walmart. about $8 for the swimming pool pH reducer, About $3 for the dye, and about $5 for the drain cleaner. I mixed up a 2 liter bottle of electolyte and used maybe 1/2 cup of the pH reducer. I figured I'd start small and see if it worked. Already have several regulated power supplies, being an electronics hobbyist and Ham.  If I get serious, I may spend some money on better supplies, tanks, etc.



I've got most of the things I need already no need some desmut and blackening supplies with the shipping cost get high figured I'd kill two birds with one stone.

Todd


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## Walltoddj (Mar 6, 2014)

Ok took a shot in the dark today and tried to Anodize a piece of aluminum. First I got no bubbling in the lye cleaner I used Draino so we are going to try to find straight lye. Put it in the Sodium Bisulfate acid bath and did see small bubbles for two hours as the 720 calculated at 15v 1.1amp on my DC power supply. The part came out with a little yellow tint as I had read in one of the articles so I rinsed it and put it in the dye. It was in the dye for about a 1/2 an hour but did not take on any color after rinsing again the part has a nice matte finish but no color. We will have to see maybe tomorrow I'll try it again if I have time.

Todd


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## darkzero (Mar 6, 2014)

Nice, I've always wanted to try anodizing alum but didn't want to mess with it at home. My buddy has sulfuric acid that I can use. Recently I needed a bunch of handles anodized clear so I thought about trying but I ended up just taking it to a local anodizer. I can only anodize titanium but that's easy.


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## Walltoddj (Mar 11, 2014)

Still trying to get the part to take the dye but no luck. Did find one thing by accident I hardened the aluminum which is the main idea I had in mind. I use battery acid in the bath with a lead plate instead of aluminum at about 24v 1.2 amp. I'm going to try to repeat this again to see if I can do it that way every time and then get it to take the dye.

Todd


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## Walltoddj (Mar 14, 2014)

Ok after a couple of tries I found that acid is the key to case hardening Aluminum tubes. I still can't get it to take the dye anybody got any ideas? Now I'll try acid with the aluminum cathode instead of lead to see what happens though they say the cathode never wears and I've got a 12"x 12" sheet I'm using it should last a while. I'm at 5 amps 24 volts for 2 hours which is in line with the 720 rule.

Todd


 	 		 			:whiteflag:


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## Alan Douglas (Mar 14, 2014)

I recall reading that some Rit dyes contain salt.


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## darkzero (Mar 14, 2014)

Alan Douglas said:


> I recall reading that some Rit dyes contain salt.



Funny you should mention Rit, I just bought a bottle a couple of days ago but I'm dying plastic. Yes, the bottle does say it contains salt. I know nothing about anodizing aluminum, only titanium, is salt bad & is Rit one of the dyes people use for anodizing aluminum?


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## JoeSixPack74 (Mar 15, 2014)

I have seen many people on the web use Rit dye and most of them have mixed results.  A 4oz package of dye made for anodizing from Caswell Plating is around $15.  After all the time you take to machine a part and polish it why go cheap on the dye?


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## Alan Douglas (Mar 15, 2014)

Aluminum corrodes in salt water, even anodized aluminum unless it's hardcoated.


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## Walltoddj (Mar 15, 2014)

Well after reading a couple of other sites the information point to the fact I stumbled on type III anodizing which is a harder surface but does not take dye. I'm going to try to make two anodizing bathes so I can try to get it to take the dye, what I'm reading is with the battery acid it needs a 50/50 dilution for type II. I think at this time I'm at a 10/1 dilution which is one of the reasons they say it is for type III. I still don't understand why the sodium bath does not work because it's still soft when hit with a file. Oh and just so you know that is my hardness test if the file cuts it it's soft, when the file slides it's hard and by that it that's a lot of pressure to cut though the anodize coating.

Todd

I can't find Rit dyes but on the dyes I've gotten you add salt or vinegar to it depending on the fabric your dying it contains no salt.


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## Walltoddj (Mar 15, 2014)

I finally got what I wanted a file hard dye able part. I found the problem is the dye, I got some Rit dry that did what I wanted a nice Gold color. By using battery acid at 16 quarts of water( I used tap water they say use distilled) to 1 quart of acid, a lead cathode, at 5 amps 19-20 volts for 120 mins. the part is a tube 1 1/2" OD x 9" long which comes out to about 85 sq inches of surface (it's anodizing both the inside and the outside). The dye has no salt I've shown a photo of the box you add salt or vinegar for cloth, I mixed it 2 quarts distilled water to 1 packet of dye I might be able to add more water but it did work this time. You can see if you look at the fifth line it said add salt or vinegar to the dye and the bare spot on the part is where I filed though the anodize.

Todd


                           :victory:


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## John Hasler (Mar 15, 2014)

Walltoddj said:


> I finally got what I wanted a file hard dye able part. I found the problem is the dye, I got some Rit dry that did what I wanted a nice Gold color. By using battery acid at 16 quarts of water( I used tap water they say use distilled) to 1 quart of acid, a lead cathode, at 5 amps 19-20 volts for 120 mins. the part is a tube 1 1/2" OD x 9" long which comes out to about 85 sq inches of surface (it's anodizing both the inside and the outside). The dye has no salt I've shown a photo of the box you add salt or vinegar for cloth, I mixed it 2 quarts distilled water to 1 packet of dye I might be able to add more water but it did work this time. You can see if you look at the fifth line it said add salt or vinegar to the dye and the bare spot on the part is where I filed though the anodize.
> 
> Todd
> 
> ...



How do you apply the dye?  Do you put it in while you are anodizing?  Dip the part in the dye-water mixture afterward?


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## Walltoddj (Mar 15, 2014)

There are a number of steps before you dye it but after you anodize it, rinse it then put it in the dye. I had a wire to it and submerged it in the dye the bald spots you see are from me filing to test the hardness of the part. Now it's suppose to go right in the dye after anodizing but I couldn't get it to take so that part was on my bench for a couple of days but still took the dye so I feel it's a good sign it's going to work out fine.

Todd


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## Walltoddj (Mar 16, 2014)

Alan Douglas said:


> I recall reading that some Rit dyes contain salt.



I stand corrected if you get a magnified glass to read the very fine print ( after the Spanish!!) it does say it contains salt I don't see where it would be a problem because you rinse it then seal it.



 	 		 			:think1: 		


Todd


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## Alan Douglas (Mar 16, 2014)

I don't know that it is a problem but apparently people have variable results.  I have done only alodining myself, and used dyes with that, and got variable results on different alloys, so the company I worked for decided not to pursue doing it in-house.

As I understand anodizing, the surface is porous while the hydroxide film is forming (it has to be, to allow current to flow). The dye penetrates this porous surface, and then is sealed in (by boiling in water, as I recall reading).  If the dye is penetrating, chloride ions could penetrate as well.


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## Walltoddj (Mar 18, 2014)

I was able to get some dry black Rit dye today and noticed something I didn't pay attention to before Rit dye is 1 1/8 oz, Rit liquid is 8 oz, and Caswell is 4 oz liquid. I'm wondering about the dilution of each dye, Caswell is 2 gals to 4 oz of dye, Rit is 1 packet or 1/2 cup(4 oz) to 2-3 gals water. I'm wondering if maybe I'm not diluting it enough and that is why black is not dark enough? The yellow I did was one packet to 32 oz of water and it looks good but it colored fast.
Any ideas?

Todd


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## Bill Gruby (Mar 18, 2014)

I am probably late with this . It explained a lot.

http://www.youtube.com/watch?v=QBWpB80xxZI

 "Billy G"


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## Walltoddj (Mar 18, 2014)

Bill Gruby said:


> I am probably late with this . It explained a lot.
> 
> http://www.youtube.com/watch?v=QBWpB80xxZI
> 
> "Billy G"



Interesting I still wonder what concentration the dye is at he had 32 oz containers but could have mixed it any way he wanted. From watching him I will dilute mine a little more to see what happens because my parts are a hard coat anodize that I'm told is harder to dye. I'm still using battery acid I find it works the best to give me a hard anodize coating the sodium is to soft for my liking.

Todd


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## Walltoddj (Mar 23, 2014)

Ok found out a couple of things current to the part is a big factor just because the power supply said 10amps doesn't mean it's going to the parts if you have more than one on at a time. I need to know if anyone is having a problem with the anode wire that you hang the part from dissolving right at the acid bath top level they seem to be getting eaten away by the acid and at time you can hear a sizzle. I did get them to dye black with the Rit dyes in 1 gallon of distilled water they came out jet black but had to leave it in for about an hour.

Todd


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## aeroHAWK (May 28, 2015)

Todd,

I'm glad to hear that you had success! I am in the process of setting up an anodizing line. I haven't yet dyed anything but I've had good success with clear anodizing. It was a steep learning curve though. The thing I found that had the most effect on the quality of the anodize is that the power supply needs to be a _Constant Current_ power supply. As the process proceeds the voltage increases in order to keep the current constant. As the surface builds, it increases the "resistance" of the whole system. A Constant Current power supply will automatically handle this, which allows much better control of the surface thickness using the "Rule of 720".

I didn't notice if you had any agitation in your anodizing tank. It is common to use a manifold of PVC pipe with holes to provide bubbles (like water boiling) to keep the bath "stirred" up. This may be why more than one part at a time may not be consistent for you.

Also, you shouldn't have the anode wire dissolving in the acid. Are you using aluminum wire? If it is aluminum wire, it will get anodized with along with the part - not eaten away.

From what I understand, Rit dye is not colorfast so I ordered my dye from Caswell. Also, black is apparently not easy to get dark, and this could explain why Caswell's black dye is so expensive. It's a lot more that the other colors.

I read somewhere that for different color dyes, the anodize thickness can be critical. I don't recall the number, but there is a minimum thickness required, I think it is just under a half thou. Also, too thick can make it more difficult for the dye to penetrate the pores on the anodize surface. My recollection is that you want to keep the thickness from a half thou to a thou.


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## itsme_Bernie (May 28, 2015)

I missed this last year!  Awesome!  I am very interested in trying this too!

Bernie


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## JimDawson (May 28, 2015)

I have a question, would a constant current arc welder work as a power supply for anodizing?


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## savarin (May 28, 2015)

I tried anodising some aluminium angle a couple of years ago and used "Dylon" black dye.
They came out light brown to a bronze colour.
Havnt done any since. Might just have to have a go again.


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## aeroHAWK (May 28, 2015)

Jim,

In theory a constant current welder should work. But in practice, a welder is designed for far more current than is needed for anodizing. This makes it likely that the current regulation at the lower current levels is not very accurate.

For anodizing, there is a "Rule of 720". This states that it takes 720 amp-minutes / sq. ft. to build up .001" thickness of anodizing.

As an example, let's say you have a part that is 8" x 8" x 1/2". This has a surface area of 144 in^2 or 1 sq.ft. If you want to know how much current you need for an hour in the tank, its 720/60 you get 12 amps for a .001" thickness. If you want to go to two hours, it will only be 6 amps.

It is not recommended to use more than 12 amps / sq. ft.

The largest parts I have anodized were .55 sq. ft. yours may be different. To further put things in perspective, I used a 65 watt 19 volt LapTop power supply (I had lying around) and a cheap Constant Current controller I got on fleabay. It works great for the size of tanks (2 gal) that I am using. I am "upgrading" to an old 250 watt PC power supply....


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## mws (May 29, 2015)

Nice first try. My first try didn't take as well. I always have trouble with maintaining good contact on the part being anodized and not making a shadowed area where visible.  I need find something to hold the part and not contaminate the bath. Titanium seems to be the favored metal.  Otherwise I've managed to get excellent results just using battery juice and a well ventilated space.  I keep a cloth dampened with Baking Soda around for any splashes.   Anodizing is a great addition to home machined parts.


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## aeroHAWK (May 29, 2015)

The only metals that should ever find their way into the anodize bath are aluminum, titanium, and lead. For hobby purposes, aluminum wire is the most common used for the electrical connection, since it is relatively easy to find and is inexpensive. I got myself a one pound roll of MIG welding wire for under $10. It will last me a looong time.

Anodizing shops use special racks to hold the parts. These racks are made of titanium. The titanium wire I found is VERY expensive.

A cloth dampened with Baking Soda is a really good idea.


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## yendor (May 30, 2015)

Can you provide more details on your use of the PC type Power Supply and the Constant Current Controller.
I have access to a ton of PC Power supplies but don't understand the Controller part.

Is there a link you could post to the controller?


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## aeroHAWK (May 30, 2015)

Rod,

Rather than hijack this thread, I started a new one here:

http://www.hobby-machinist.com/threads/diy-anodizing.35868/


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