anodize, anodizing, home anodizing, diy anodizing, how to anodize, learning anodizing
Let's first get some nomenclature out of the way. I say anodizing. Some call it anodising. Just depends on which side of the pond you come from. Some may call it aluminum anodizing, others may say aluminium anodising. I kind of like the sound when a european says aluminium, but I grew up saying aluminum. However, looking at the periodic table of elements, I believe the Europeans have it right when they say aluminium. So, for the sake of variety, I may say aluminium anodizing at some point. Since we'll be using sulfuric acid, we should get that out of the way, too. Sulfuric acid is H2SO4, commonly called battery acid by non-chemists. It may also be called sulphuric acid. At some point we may be talking about titanium racking systems, too, but I don't think there's a large variety in the ways to spell titanium. Current Density & constant current anodizing are important. voltage controlled anodizing may work, as well as battery charger anodizing, but I'm not going to recemmend those.
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Anodizing Aluminum
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| This website comes from the the rambling mind of Bryan, and some of his knowledge on the subject of small-scale anodizing.
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It all started back in the college days, when a friend decided he needed to anodize a paintball gun. He had found a magazine article claiming that with some battery acid, RIT clothing dye, and a battery charger it was possible to achieve a good quality anodized finish at home for a fraction of the cost. As you may guess where this is going, it didn't work so well.
However, after a couple of years of reasearch, trial and error, and way too many hours of polishing aluminum, I finally found a method of anodizing that works well for the small scale anodizer.
My basic method could be described as a modified version of the low current density method proposed (and sold) by Caswell Plating. In the low current density method, Caswell recommends using a constant current source and a low concentration sulfuric acid bath. I tried this method, and it worked, but I was still not 100% happy with the results. By using a constant current density of around 12 amps per square foot (ASF or amps/ft^2), and a higher concentration sulfuric acid bath, I could achieve the same or better results in about half the time.
I must give credit to Ron Newman, who has had an anodizing site up for quite some time. It was his original site that prompted me to even attempt anodizing at home. Although I can't say I agree 100% with his method of using a battery charger as the power supply (and yes, I have tried it), I do agree with most of his other information. I have bought some dye from Ron and I was very pleased with the service I received from him. I would recommend doing business with him.
Let's get started with the basics: What will you need to set up your own cheap, inexpensive do it yourself (DIY) home anodizing line? This will be for type II anodizing (type 2 anodizing). That is the type of anodizing that takes dye well and is typically used mainly for cosmetic purposes, but also adds a hard aluminum oxide coating to the part that is very corrosion resistant as well as wear resistant and has electrical insulating properties. I'm getting ahead of myself, though. Back to the concept at hand: What do you need to set up your own anodizing kit?
Items needed:
- Tanks to hold sulfuric acid (anodizing bath, or anodizing solution)
- Aluminum parts to anodize
- Power supply. Should be capable of constant current, have a high enough current capacity, and go to at least 20 volts
- Sulfuric acid (battery acid) to make acid bath
- Aluminum wire or titanium wire to hold parts
- Distilled water. It's cheap, so buy lots of it.
- Anodizing dye. Don't bother with the RIT clothing dye, it doesn't work well. Buy good anodizing dyes, they're not expensive, either.
- Degreaser. Aluminum Parts must be surgically clean before anodizing, or the color won't be consistent.
- Desmut (optional)
- Sealer (optional)
- Lye, also known as sodium hydroxide (NaOH). Used to strip existing anodizing off parts.
- Baking Soda. Keep a large amount of this on hand to neutralize acid in case of accident.
Getting started:
Basic Steps:
1. Clean the aluminum parts.
2. Degrease the aluminum parts.
3. Anodize in the acid bath at 12 amps/square foot for 45 minutes. Keep temp at 70-72 degrees (F).
3. Remove parts from acid bath and rinse with distilled water.
4. Dye parts (if desired) in warm dye, ~100 - 140 degrees (F).
5. Seal parts by placing in boiling distilled water for 20-30 minutes.
A typical DIY setup for beginning anodizing is show on the right. A 5-gallon bucket will work for small parts, the large plastic storage totes offer a variety of shapes and sizes available for larger parts. In my experience, these have worked well. These will be the tanks that will be storing your sulfuric acid anodizing bath, so take caution to ensure they will not leak.
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Fade Anodizing
Basic DIY Anodizing Kit
Anodizing Power Supply
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