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Anodizing Overhead - storing and disposing of acids and solutions

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PurpLev

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  1. PurpLev - 03-12-13, 06:46 AM
    I've read about anodizing and this is something that theoretically I would like to be able to setup at some point. Once things that I have not been able to find much information about is the after effects - once you've anodized your parts, how do you handle the liquids (acids, washing water, dyes)?

    Do you store those ? if so, in what containers, how and where?
    Do you dispose of those? if so? where and how do you go about doing so?

    What have you to say (before I consider getting into this, I gotta know how to get out of it as well)?​
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  2. eac67gt - 03-12-13, 10:13 AM
    In my process I have the anodizing solution, sodium bisulfate and distilled water, in a 2 gallon bucket I picked up at Home Depot. I purchased a lid for this also. When not in use I remove the cathode and rinse it off good in the sink then just let dry for storing.
    Before I close up my tank I skim the small amount of dirt, for lack of a word, off the top with either a paper towel or just scoop it off with a small plastic spoon. This solution gathered can be dumped down the sink because of its nature.
    Sodium bisulfate is the same thing you use in your spa or pool to decrease PH level. It is not like sulfuric acid where the government is not happy with how you handle it.
    Once I clean up the debris off top I seal the bucket with the lid. They say this can be stored for up to a year. I check the acid level periodically with my hydrometer that I use for car batteries. The specific gravity of each is about the same so if it is in the range of what a car battery should be it should be good to go.
    I have already left the cathode in the tank for several weeks without use and it grew crystals on the cathode. I got about a cups worth of crystals off of it. Kind of cool!
    From my research if you want to dump the anodizing solution, sodium bisulfate, on the ground outside you can. Be careful because it is a salt. Salts will tend to kill grass or at least damage it.
    The cool thing with the sodium bisulfate is you will not find it eating holes in your cloths like sulfuric acid will.

    The dyes can be stored up to a year also. Once cooled down I pour the dyes back into a 1 gallon jug the distilled water came in. I label the jug as per color. I also put each jug in a 2 gallon zip lock bag as a leak precaution. It is best to allow the dye to become ambient temperature and if putting in bag to make sure it is completely dry to try to limit mold.
    When you get dye back out for use make sure you bring it to temperature 120 to 140F and stir well to insure solution is re-dissolved completely. If it is not spotting can result on your piece being anodized.

    All water in process is distilled water. The exception is when doing any washing or pre-rinsing. All rinsing with tap water is always immediately followed up with spraying the part down with distilled water. Tap water has lots of mineral containments that will ruin the anodizing.
    Once again all this water can go down drain.

    Washing your parts starts with a bsic degreaser like dish soap or I use Purple Power. Purple Power seems to dissolve my polishing compound better. These soaps can also go down drain. Scrubbing the parts is the most important thing. You can not have any polishing compound, oil, dirt... on piece.
    The part can be tested with using distilled water and spraying the part. If the water sheets off it is clean. If there is any sign of water beading like it should on your car than there is contaminates left behind. Rewash.
    I stress you must scrub well. Any thing left in holes or grooves can leech out during anodizing and contaminate the part or the tank. I have all kinds of brushes to get into all the little spaces. A ultrasonic cleaner might and I say might work well to clean the parts.

    At this point you can go to an additional step I do and that is to etch the part. There are opinions on this but it issuers, to me, that the finish has a little more integrity.
    I use a Etch solution (metal brightener) it is called Pro-power Acid Cleaner C-24. Contains sulfuric acid, phosphoric acid and hydrofluoric acid. It is highly concentrated and gets diluted 10 to 1. I bought it at the auto body supply shop. He said they use it to clean the big aluminum tankers on tractor trailers. I found it to give me a more uniform finish but I also found in some cases I didn't need it. It seems to be a call at the time on what part I am anodizing. The issue is if the part is real freshly machined and there was no time for the aluminum to oxidize than this will not be needed. Aluminum starts to oxidize fast so to insure its removal I do this step.
    This solution I mix I use over and over again. The parts being dipped in it are suppose to be clean so the solution being contaminated should not occur. I keep it in a one gallon plastic pale with a lid. The parts are dipped for a couple of minutes. How I time it is by watching the parts. When the oxidized layer is removed the part will bubble like mad. That is time to remove the part. Not very good method but it works for me. These acids will eat this part but if controlled there is no problem. It is one of those processes you don't put them in and walk away. It must be monitored.
    Disposal of this is questionable. All of these acids are used in some sort of drain cleaner. I have dumped it down the drain but follow it with lots of water. It should not in anyway destroy the pipes but then all mine are plastic. I think that is why it is a good idea to follow with ltos of water.
    This is another solution that if kept in the plastic container with lid will last a long time. It should not go bad where it will destroy a part but become weak.

    The one other chemical I will use occasionally is lye, sodium hydroxide. I use it to remove anodizing. The thing with anodizing is there are only a few ways to remove it. A strong caustic solution or by machine. The slow safer way I found was to use Greased Lightning. It will give you a more diluted. slower acting lye solution to remove the anodizing. The faster way is to use pure lye and a water mix. I put about one tablespoon of lye into one cup of water and make sure it is mixed well. If not mixed well the small particles will pit your part. This is a method that has to be constantly tended to so yoo can monitor the progress. Scrub part with brush every 10 seconds or so to remove anodizing and progress the removal process.
    This solution can be also dumped down drain. It is in some soaps and drain cleaner. I again follow it with lots of water.
    The difference between the Greased Lightning and the pure lye is one will take about 30 to 60 minutes and the other I can have done under a minute. The lye method is risky in you can destroy a part.

    Cost for the whole process of anodizing at home can easily be kept under 100 but it is all in what you have laying around and how big you want your process.

    In this whole process I always want tot stress protecting yourself.....hands and eyes!

    I imagine I created either confusion or many more questions.

    Have a great day!
    Ed​
 
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Tanguero

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In the UK both concentrated sulphuric acid(98%) and anhydrous sodium hydroxide are sold as drain cleaners. When my anodizing bath is no longer required I shall clean my drains. Likewise my etch bath, though not at the same time! Either of these followed by plenty of water should be reasonably environmentally friendly in domestic quantities. The nitric acid de-smut bath is of more concern and one I certainly won't be putting down a drain.
 

xalky

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In the UK both concentrated sulphuric acid(98%) and anhydrous sodium hydroxide are sold as drain cleaners. When my anodizing bath is no longer required I shall clean my drains. Likewise my etch bath, though not at the same time! Either of these followed by plenty of water should be reasonably environmentally friendly in domestic quantities. The nitric acid de-smut bath is of more concern and one I certainly won't be putting down a drain.
Most acids can be neutralized with lime. But I'm not sure what compounds you're left with once it's neutralized. I'm sure that info can be had on the net.
 

eac67gt

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I just wanted to add about any acid that a good idea is to keep a box or so of baking soda sitting around in case you spill some.
(this may have been said before by someone?) :dunno:

Ed
 
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