I did not write this article. The gentleman who signed it at the end did. I just wanted to share another resource I have.
Anodizing 101
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. Don't use
hot water! You'll 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 parts.
You can check out the above, as well as pick the colors you like best. If you
test out some colors, you'll 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.
T. Gray Jr.
