Step 4: Anodising your part

Now we have a problem. We want to make sure that we only have Aluminium in the Lemon Juice, but we also want the whole part to be immersed, so it can Anodise properly.
The way I did it was by only inserting half the piece, and every ten minutes or so rotating it, so it ended up coating evenly enough.

Any part that touches the bottom or sides of the container also will not be anodized.

Run it. Let your piece sit in the bath for an hour or more.
- Bubbles will form. This is normal, and it is the formation of Oxygen gam at the Anode that makes the process work.
- Your solution may heat up as well. This isn't desirable as it will cause different speed plating, and so different size 'pores.' The only way I can see to offset this is to only run it for shorter periods at a time, and have a big container that will hold coolness for longer. I never noticed this as a problem, but if you are doing it commercially it might be.

If you remove the part from the bath and clean off the bubbles you will see that the object has gone matte. This is because the surface is now pitted with tiny little holes in a layer of the darker Aluminium oxide. When the layer is only thin, this can be scratched off with anything metal. When it is thicker it still can, you just don't notice it so much!

Finally remove the part from the bath, and rub it with some toilet paper to remove the lemon juice. 
<p>If you wanted to concentrate your vinegar, you can purify by distillation. Same principle as distilling alcohol: heat it up and collect the water, then collect the purified acetic acid. </p>
Your cathode has to be more Nobel than your anode(part you are anodizing) look up Nobel chart of metals or galvanic scale. For example: if you are trying to anodize a piece of aluminum and you use a piece of zinc or magnesium for an intended cathode, your anodizing will work in the opposite direction. The further apart the two metals are in the galvanic scale the stronger the effect will be.
<p>Yes, you definitely know what you're talking about. I'd give you 5 thumbs up on here if I could.</p>
<p>As far as using lead, I understand what they are referring to, it's about having dissimilar metals in the tanks, it's akin to the idea of electro-plating as well, a similar process.</p><p>The reason for the use of lead is that it has a lower electrical resistance than aluminum has per centimeter and overall surface area resistance is also lower. Of course, this also differs depending on the grade of lead you're using and the other impurities found in said lead or aluminum you're using.</p><p>If you don't wanted to use lead, you can use zinc. For example, use zinc in place of the aluminum can that was used. Also, it depends greatly on how close your object your anodizing is to your plate you have charged up inside of the jar.</p><p>Make sure that if you do use vinegar (acetic acid) that you use white vinegar, you get better results with that, as it's more purified. If you use lemon or some other citrus fruit, which is the real citric acid, that you strain all the pulp out but slowly boil the concentration first, removing excess water, the point is this, don't make it too acidic nor too weak, it has to be just right. If you got to add water, for frack sakes, don't use tap water, you're adding impurities into your acid bath, which might neutralize the effects or give you screwy results. Make sure you use de-ionized water for this.</p>
I have read around and seems though that 4-12 volts for a square foot of aluminum you are going to anodize. As well if you want to use something better than lemon juice or vinegar, you can use ph down pool additive, containing sodium bisulfate easier to get a hold of than battery acid (sulfuric acid)
<p>Interesting 'ible - I may have to try this at some point.</p><p>If you are interested in trying other acids, I would suggest starting with citric acid. It's commercially available, cheap (&pound;3 for 500g on e-bay), non-toxic (edible in fact) and is the main acid component of lemon juice so it should be similar to a highly purified version of what you are using now. I'll let you know how it goes if I manage to try this.</p><p>Cheers</p><p>Ugi</p>
<p>Adding teaspoon (or more) of salt to vinegar will increase it's conductivity.</p><p>However i am not sure if anodizing as suggested by this instructable will give you same qualities as more advanced methods... can somebody make comparison based on experiences with the two or electrochemical knowledge?</p>
<p>You can use any electrolyte really. I've recently started just using plain salt again, but beware of chlorine fumes.</p><p>Anodizing by this method will not be as good as by more advanced methods because ... it's simpler.<br>For a consistent surface you need the temperature and pressure regulated, you need an even charge distribution as well. This was not taken into account in this ible because I was looking for the simplest possible method to color metal. I was seeking only porosity not durability.</p><p>If someone finds a better method though, please tell me!</p>
Sorry, great post!
You said if anyone knows why one site recommend Lead let me know, so here it goes... Some metals are more active ( Anodic), or more likely to corrode, other metals are less likely to corrode or more noble ( cathode). When you add an electrolyte, metallic path, and a current source, a natural reaction occurs, where the more active ( anode) sacrifices itself to protect the cathode.
Would it be possible to wrap bare copper wire around the inside of the glass jar to use as the anode? I've seen it done on a larger scale in 5 gallon buckets, but he was using industrial chemicals and it wasn't quite the &quot;can do at home&quot; type of set up. I only ask because I see you mention if the lemon juice turns green it means you have some copper in there somewhere, so I am guessing it's not a god idea with this particular set up (?).
Actually, it will be fine using copper for the cathode. Just make sure that you don't end up copper plating the part (check the polarity of the wires).
Try pickleing vinegar it is much stronger than regular table vinegar, might help...
I would love to see posts about your experimentation with other organic acids.
I'll let you know whit I've tried. <br>I've just added Vinegar to the ible, and plan to try orange juice and some other stuff sometime soon.

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