anodizing aluminum receiver

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bobditts

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I recently purchased a ruger 10/22. The barrel is stainless but the aluminum receiver is coated with a gray colored paint (atleast I think its paint). I want to safely strip all of the coating off and leave the aluminum exposed. Is there a way to anodize it myself or is there a better way to protect the aluminum? Thanks!
 
Anodizing is the absolute best way to protect aluminum.
I found this on the net while considering anodizing an AR lower. Hope
it helps someone. There are links to other anodizing sites at the
bottom.

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 chemical 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.

(Editor's Note: While Mr. Bowes recommends not using a glass
container, we highly recommend use of glass within a plastic container
to help keep the acid from eating through plastic, but keeping the
glass less breakable in the event the container falls over.)

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
paintgun's 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.

Other Links:

www.geocities.com/CapeCanaveral/Galaxy/7004/
asuwlink.uwyo.edu/~metal/anodizing.html
www.atmpage.com/anode.html
www.ptw.com/~gsxr1100/anodize2.html
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There's a good chance the reciever is powder coated. Very hard to get off and a very durable finish. Poweder coating may be an option to you, the finish colors are almost endless.
 
Thanks for the article. Sounds like something I might try this summer. Im not sure if it is powder coated or not. I know it is coming off pretty easily where the bolt makes contact with the inside of the receiver.

Anyon e know of any major chains or popular stores that would carry the acid I need?
 
You can simply sand the anodizing off, and leave the aluminum bare. It won't hurt a thing. If you sand it to 600 grit finish, and then hand buff it with 0000 steel wool the finish will be very pleasing.
BTW- the BEST way to protect aluminum is with nickel plating.
 
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Im not looking to get rid of the anodizing. It isnt anodized yet, thats what Im trying to do. Ill have to go to autozone and get a small dose. I dont think it will take much to do the receiver.

Does anyone see any problems with this idea? I plan on polishing the surfaces perfectly smooth before hand. I would think this would help for a smoother bolt action than anything right?
 
My Ruger is anodized. Perhaps later ones are painted.
I don't think that anodizing will necessarily smooth the action. Anodized surfaces are extremely hard, but the layer is very thin and it doesn't take much to damage it. Once you get past the layer of anodized metal, the rest of the layer will rapidly wear. I assumed you were more concerned about the color. Raw aluminum will "self-anodize" after a fashion. A layer of aluminum oxide forms very soon after aluminum is exposed to air. Anodizing leaves a much thicker layer, but it still does not wear well. Electroless nickel plating holds up much better. I would leave it raw or plate it. Home anodizing is not difficult, but it is messy and dangerous. Unless you need coloring I don't feel it is worth the effort.
 
Like any kind of electroplating, there will be a learning curve. If you try it, don't make your receiver the first thing you try. Also, what you want ideally is what is called hard anodizing. I don't know how the process differs, but I have an old Beeman's pellet seater with a hard anodized surface that has never been scratched even after tens of thousands of touchdowns on the breech of a steel barrel.
 
If your in Denver area then there are a number of plating shops reasonably close to you.
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If they are going to keep the receiver overnight they need to be an FFL.
The receiver IS the gun on a 10/22.
 
If it's painted, you might try a little acetone on a hidden area to see if it will remove the paint. If acetone doesn't do it, try MEK - it will dissolve darn near anything, including epoxy.
 
The Ruger receiver is powder coated. Leaving it alone is actually a better idea than removing the finish, because the casting will oxidize without the finish on it, and the powder coat finish is harder than the receiver itself and provides some lubricity and wear resistance. If you just gotta, you can bead blast the receiver and GunKote it with silver GunKote, and you will have a tough epoxy finish that will protect the firearm and wear well. GunKote goes on very thin and adds very little dimensionally to the receiver, so parts do not get tight or loose as a result of refinishing. I painted a 10/22 with GunKote last year, and the results were very pleasing.
 
This sounds like a normal anodizing procedure, not 'hard anodizing" which is what you'd probably want for gun parts. It's much harder and more abrasion and corrosion resistant.

I think you'd be better off just taking your parts to a plating shop.
 
This sounds like a normal anodizing procedure, not 'hard anodizing" which is what you'd probably want for gun parts. It's much harder and more abrasion and corrosion resistant.
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From what I have seen at my aerospace customers' locations, there is virtually no difference in procedure between what you call 'normal' anodizing and 'hard' anodizing. The difference is in the amperage applied. This is accomplished with current and temperature. More amperage means a slightly (really slightly) thicker anodized layer. Hard anodizing also has less voids in the microscopic surface than normal anodizing.

That being said, anodizing only affects a thin surface layer. The substrate is unaffected. You will hear that hard anodized aluminum is 30% harder than stainless steel. That's true, but only for the oxidation layer created by the anodizing. If the oxidation layer is abraded completely through, the underlying aluminum is a soft as it was before it was anodized.
 
They haven't been anodized for decades, it will come off pretty easy with some wet sanding. The receiver and trigger guard polish up well. I've used nothing but nano wax to protect it.

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The difference is in the amperage applied. This is accomplished with current and temperature. More amperage means a slightly (really slightly) thicker anodized layer. Hard anodizing also has less voids in the microscopic surface than normal anodizing.
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For type III (hard anodizing) higher amperage is applied because the solution is cooled to 32F (this step is not described above and therefore I would not call it hard anodizing). Hard anodizing generally results in thicknesses from 2 to 8 times that of type II anodizing. Hardness on type II tops out at about 55 Rc, whereas type III can go to more than 65 and possibly 70 Rc. Measuring Rockwell hardness does not work well for anodizing, but I show rough equivalents because gun people are probably more familiar with it.
 
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