Glan Noye
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| posted on 27/7/05 at 12:06 PM |
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Anodising
This could be worth a try! Anodizing at Home
by Jim Bowes
Based on the number of companies selling, and people looking for, anodizing services for their gun's aluminum bodies and parts, I wanted to
provide this info to the paintballing community. I first came across the process in Super Chevy magazine, in an article about anodizing your own parts
and brackets, for a custom touch on your hot rod. (* Original article by Bruce Hampson.) Often anodizing is considered and/or presented as a difficult
and expensive procedure. As it turns out, it really isn't that hard or that pricey. Supplies Needed:
The first thing to do is to get the following things together: First on the list is the most expensive item: a 6 to 12 volt battery charger. This item
is what might make this too expensive for some paintballers. I (and most other hot rodders) already have one, for my car. If you don-t, then you will
need to pick one up. They run from $45.00 to $110.00 depending on model, Functions, etc. While it may seem like a lot, it does have other uses. (You
could charge a battery, for example.) =) The next item, though not that expensive, will take some effort to find: battery electrolyte, a.k.a. sulfuric
acid. This should be available at a battery wholesaler for about $2.00/gal. To make the negative ground, you will need some aluminum ground wire and
aluminum-foil. The wire can be found at an electronics store for about $35/spool, and you should have the foil in the kitchen. If you happen to be out
of foil, you can pick up some more at the store when you go to buy the last item for this project.
No super-special chemicals or solutions necessary to make the colors; just plain-old fabric dye. (Something like Rit dye, for about $5.00.) Rit offers
something like 30-40 different colors, so you have quite a number of choices for what color you want your parts to be. An optional item is nitric
acid: about $25.00/2.5 L. (This is used to clean parts prior to anodizing, but there are some cheaper alternatives. See end notes.) This is available
at chemical supply stores. Should you not be able to find any, you can try to get on the good side of the high school science teacher. He may help you
out since you only need a few ounces.
Safety Precautions:
There are a few precautions I want to go over to help keep you from blowing up the house or trashing the garage. First of all, do not mix or store
your anodizing solution in a glass container. Something could happen to make it break, and most households are not equipped to deal with that kind of
spill. You also don-t want to knock over the container, so a stable, rubber bucket makes a good choice. You will also need to be certain that the part
you want to color will fit in the container without sticking out of the solution, and without touching the negative ground in the bottom of the
container. Any acid that you don't use, keep in what it came in, or an old plastic bottle, like a bleach bottle. You can also store your used
solution this way for doing more parts later. (Make sure that there is absolutely no bleach left in the bottle. Acid and bleach make chlorine gas.
Very bad. Don't breath. Poisonous.) Safety also applies to the nitric acid, but in a different way. It is imperative that you label and keep
track of this stuff, as it is a stronger acid than sulfuric, and more dangerous. The breakage/spill problem is not as likely since you won't
have that much around. (Unless you bought more than a few ounces from the chem store.) The last note about the acids is to mix properly when adding
acid and water. Always pour acid into water, never the other way, and do so slowly, being sure to mix in well. There is a reaction taking place and it
releases a lot of energy. During the anodizing process, you will be running electricity through a weak acid solution. This creates hydrogen (just like
charging a battery) which is very flammable. This stuff burns at the speed of thought when ignited, so do be careful. (Read as Remember the
Hindenburg?) Make certain that there is some way to ventilate the project area, and DO NOT let any sources of ignition near the project area. Other
precautions you should take include safety glasses, rubber gloves, and maybe some sort of drop sheet under the area.
Preparations:
One of the most essential things you need to do in order to get even color over the whole part is to be sure that the part is absolutely clean. You
want it free of all contaminates, from dirt to the oils in your skin. This is where the nitric acid and some rubber gloves will help. A solution of
1-2 ounces of nitric acid in a gallon of distilled water will allow you to clean the surface in preparation for the anodizing. Aluminum oxidizes very
quickly when exposed to air, so the easiest way to keep it clean is to clean it just before you are ready to start working on the piece. (You should
rinse the part with distilled water before you put it in the next acid solution.) Other options are carburetor or brakes cleaners, or other similar
degreasers. Soap and water will work also, or cleaners like Simple Green. These are cheaper, a nitric acid wash is the best. (You decide, it's
your money.) =) Make your negative ground with the aluminum wire and foil. Shape the end of the wire into a paddle shape and cover the round part with
the foil. What you want to do is create a flat, round shape to sit on the bottom of the bucket, with a lead that comes up out of the bucket. You will
clip the battery charger's negative lead to the wire that comes out of the bucket. When you are ready to start, you will want to mix up your
immersion solution. In your rubber bucket, combine the sulfuric acid and water to come up with a solution that is about 30% water. (1 part water to 2
parts acid.) Place the paddle in the bucket and attach the negative lead. Then attach the positive lead to the part, making it an anode, and immerse
it in the solution. (Remember that the two leads the paddle (cathode), and the part (anode) should not touch.) This is the best time to turn on the
charger: once the part begins to fizz, leave it in there for about 10-15 minutes. After about this time the part should no longer conduct electricity.
(You can also use an ohmmeter to check conductivity, but this is not needed.) Turn off and disconnect everything, and rinse the part in cold water.
DonÀ Àt use hot water! YouÀ Àll find out why in the next section.
A couple of notes:
I have read some other procedures that say it is important that the copper lead from the charger does not enter the acid solution. The article says
nothing about this, and shows a picture with the lead right in there. It may take some trial and error to find out if this is a problem. It
wouldn't be a bad idea to get some scrap aluminum and play with it before you start anodizing your paintgunÀ Às parts. You can check out the
above, as well as pick the colors you like best. If you test out some colors, youÀ Àll also learn just how long or short you need to work with the
color solution.
Color:
So now it doesn't conduct electricity, and is ready for color. It's been rinsed and waits eagerly to change to a new look. Don't
wait too long to do the color, due to that oxidizing thing again. You want to mix up a strong solution of dye and water, in a container that can be
heated. The solution needs to be at low heat, such as on the stove, so bread and cake pans work well. Again, you need something that will fit the
whole part, but it's okay if it touches the bottom this time. I would recommend turning parts every few minutes just to make sure that you get
all-over color. Inform your mom or wife that the pan can (and will be) washed out. It is important that the heat be low enough. If the solution gets
too hot, you will seal the surface, and it will no longer take any color. (See, told you to rinse it in cold water!) Leave it in the dye until the
part is slightly darker than you want it. The next step is to seal the surface of the metal in clean, boiling water. This will leech a bit of color
from it, thus the slightly darker color in the previous step.
End Notes:
It is important to realize that the process described above will yield only one color on your part. At this time, I haven't found out how to do
any of the splash type of anodizing. (That's okay though, it looks really ugly anyways.) =) Should anyone happen to figure it out, I suggest you
submit it to Warpig so they can put it up for others who like it.
Also, this process is for aluminum. I don't know how, or if, it will work on other metals. (I doubt it.) Anodizing only works well on rock metal
like bar or sheet stock, as opposed to castings. If it was forged or machined, it should have the density to take color through this process. I figure
this shouldn't be too big a problem with the guns, but just thought I should let you know about it.
Something to consider when looking for a charger, is how many amperes it puts out. Without getting into any mumbo-jumbo, anodizing relies on 10 to 40
amperes per square foot. For small brackets and such, this is no problem. The larger parts in a gun however, may need the higher levels of amperes.
The other note about part size, has to do with how long you leave it in the solution. Above it said 10-15 minutes, but that is for a smaller part. The
larger parts may not only need higher amperes, but more time as well. I would recommend an ohmmeter, but again, I have one already.
So there you have it. Quick, fairly easy, and not too expensive. If you don't have the charger, then your first anodizing session could cost as
much as sending your gun out to be done. But, then you can do it again for much less. Or do your buddies stuff. Or talk them into chipping in on a
setup for all of you to use. We all know ways to help make things cheaper.
And the stupid statement required to cover myself... If you try this and something gets messed up, or someone gets hurt, you are on your own. Deal
with it, you can't blame it on anyone else
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Bob C
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| posted on 27/7/05 at 02:02 PM |
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Anybody know how to DIY hard anodising? handy for disc bells - costs stupid amounts to get done professionally.
Alternatively anyone know who does it cheap!
Bob C
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timf
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| posted on 27/7/05 at 02:12 PM |
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i got a new frost catalouge they seem to be selling diy anodising kits now
see here
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RazMan
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| posted on 2/8/05 at 08:40 PM |
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Seems a good idea if you want a fair amount of anodising done - quite expensive for just a pair of caliper brackets though 
http://www.frost.co.uk/item_Detail.asp?productID=9141
I quite like the ghetto approach  ........ now where did I put that battery charger ........
[Edited on 2-8-05 by RazMan]
Cheers,
Raz
When thinking outside the box doesn't work any more, it's time to build a new box
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Aloupol
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| posted on 3/8/05 at 10:14 PM |
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Before anodizing you scour the parts with nitric acid, I saw that it worked very well with NaOH (don't know how you name that nasty stuff in
english) which is more easy to find. I used (very carefully) pH14 NaOH solution for this use.
It removes all from the aly (inclusive eventual previous anodization) and if you forget your parts into it, it's an alternative way of getting
rid of them...
The cons: as well as the other liquids that you recomend to use, we are soluble into it. (Can become a "pros" in some very specific
cases).
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andkilde
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| posted on 4/8/05 at 12:56 PM |
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quote:
Originally posted by AloupolNaOH (don't know how you name that nasty stuff in english)
Sodium Hydroxide or Caustic Soda -- very nasty to deal with.
Available readily as Crystal Draino (drain opener) on this side of the pond, has a few sacraficial flakes of ali mixed in to keep the stuff from
chewing straight through your pipes.
Cheers, Ted
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