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Scott V2
July 24, 2007, 11:33
How does one go about fixing scratches in anodizing? The scratches are actually very lightly etched initials. I want to fill them in and make them go away. It is not into the aluminum, it just scratched the "black" off

Ideas?

dougjones31
July 24, 2007, 13:01
http://www.brooktronics.com/Anodize%20Repair.htm

Most definately not cost effective to try to repair any other way than a simple touch up paint, but you did not ask for a cheap fix!:biggrin:

NoNotAgain
July 24, 2007, 16:33
Originally posted by Scott V2
How does one go about fixing scratches in anodizing? The scratches are actually very lightly etched initials. I want to fill them in and make them go away. It is not into the aluminum, it just scratched the "black" off

Ideas?

Scott,

Have you actually removed the anodize or just the colored sealer that they used?

The reason I ask is that you can do "Brush plating" to repair an anodized surface.

To determine if the anodize is removed you need a volt ohm meter. Anodize is non-conductive.

Place the probe from the meter on the exposed surface and then a bare area, (like an AR15 take down pin hole) meaning a location that a pin or screw is threaded into.

Anodizing is nothing more than a controlled oxide layer that is created either in chromic or sulfuric acid being the most common.

I sometimes have to brush plate instrument panels that have been scratched. You will be able to see a difference in the color of the surface.

Scott V2
July 24, 2007, 16:43
Originally posted by NoNotAgain


Scott,

Have you actually removed the anodize or just the colored sealer that they used?

The reason I ask is that you can do "Brush plating" to repair an anodized surface.

To determine if the anodize is removed you need a volt ohm meter. Anodize is non-conductive.

Place the probe from the meter on the exposed surface and then a bare area, (like an AR15 take down pin hole) meaning a location that a pin or screw is threaded into.

Anodizing is nothing more than a controlled oxide layer that is created either in chromic or sulfuric acid being the most common.

I sometimes have to brush plate instrument panels that have been scratched. You will be able to see a difference in the color of the surface.

very fine silver is showing, I assume it is all the way through. It is a dull black anodize finish on an ACOG scope. The scratching is so faint that a black felt marker covers it, but is the wrong color. I thought about using a flat black paint and "filling" in the scratch and then buffing it out

NoNotAgain
July 24, 2007, 17:13
Originally posted by Scott V2


very fine silver is showing, I assume it is all the way through. It is a dull black anodize finish on an ACOG scope. The scratching is so faint that a black felt marker covers it, but is the wrong color. I thought about using a flat black paint and "filling" in the scratch and then buffing it out

Brownells sells a pen for light touchup made by Birchwood Casey.

Super Black™ Flat Black Touch-Up Pen

Birchwood Casey also makes a blackener for aluminum.

Aluminum Black® Metal Finish
The room temperature chemical used by gunsmiths and industry to blacken aluminum parts. Restores
scratched and marred areas quickly. Fast-acting liquid is easy to apply with no dimensional change.
Color will vary from deep gray to black depending on alloy. ALUMINUM BLACK Metal Finish is also
excellent for blackening name plates, plaques, trophies and other engraved items.

Try the pen first and if you don't like the results get the liquid and coat the whole scope body.

Scott V2
July 26, 2007, 08:29
Originally posted by NoNotAgain


Brownells sells a pen for light touchup made by Birchwood Casey.

Super Black™ Flat Black Touch-Up Pen

Birchwood Casey also makes a blackener for aluminum.

Aluminum Black® Metal Finish
The room temperature chemical used by gunsmiths and industry to blacken aluminum parts. Restores
scratched and marred areas quickly. Fast-acting liquid is easy to apply with no dimensional change.
Color will vary from deep gray to black depending on alloy. ALUMINUM BLACK Metal Finish is also
excellent for blackening name plates, plaques, trophies and other engraved items.

Try the pen first and if you don't like the results get the liquid and coat the whole scope body.

I am going to have to get one of those pens.
-Scott

Radio
July 26, 2007, 12:31
From the Old Blue Board:

"I have re-anodized, and it's pretty easy"

Posted by CH1291
January 6, 2000

If you want to re-anodize a part, all you need is sulphuric acid (battery acid), a plastic bucket, a high power battery charger, and some foil. Dye to appropriate color.

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. 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:

* 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 people. 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. :D)
* 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 brake 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 wife or girlfriend 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 ***** 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.

Slick
July 30, 2007, 18:18
Originally posted by NoNotAgain
Birchwood Casey also makes a blackener for aluminum.

That's what I've used... I had to cut off an aluminum scope base and the trick to getting the color a deep black it to keep rubbing the part as it works really slow.

It took me ~45 minutes to get a color match - so understand that time is involved and plan on watching an hour-long TV show while you do it.

DarkEarth
August 06, 2007, 14:30
Why not repaint the ACOGS housing with Alumahyde?


If you do really well at it, then you've got extra Alumahyde to do other parts in the future. Complete ARs / mounts . etc.




Yeah that Sharpie is a little purple right?