Refinishing aluminum?

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jamesbeat

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How would I go about getting a durable black finish on bare aluminum?

I've been searching for hours, but aluminum seems to be a pig when it comes to applying a coating

I've looked into anodizing, but since it's such a small job (and I don't have any friends in the anodizing business) it is practically impossible to find anywhere to get it done.

Aluminum doesn't like paint, and most paints will peel very quickly.

There are products similar to bluing cream to blacken aluminum, but I have heard mixed things about them, that they don't give a good finish or rub off easily.

Any ideas? :confused:
 
I haven't had much luck finding an anodizing shop that will do such a small one off item. I live in New York, Long Island to be specific.

Bake on paint was what I thought, but i'm concerned that adhesion to aluminum would be poor and it would end up flaking and peeling.
There are etchant primers that help, but I'd like to avoud using a primer as they are usually not black and would thus look terrible when the finish started to wear.

I'm half tempted to try anodizing at home, but the setup costs just for one item would be prohibitive.
 
Alodine 1200 is often used as a corrosion inhibitor and a metal prep for epoxy primer. That's the standard for aircraft...maybe a little much for what you're doing...?
 
Is this a firearm?

If so, an anodizing shop cannot refinish a firearm legally unless they have an FFL.

If it's a firearm of any value, it would be worth the money to send it to a firearms refinisher and have it hard anodized properly.

If it's an aluminum water bottle or something, bead blast it and use Duracoat shake & bake spray paint.

rc
 
Birchwood Casey has an aluminium black. It does a fair job, but the finish is more of a matte, you have to use several applications to get it the shade you want, after it is oiled it has a somewhat shine. It also leaves a mottled finish if the bare aluminum is not absolutley clean, best to wear rubber gloves so the oil from your fingers.

If this is a small part this may seem a little weird :uhoh:but I read a soultion out of Brownells GUNSMITHS KINKS, I tried it and it does work very well . I re-blackened an aluminum trigger guard .

You use olive oil, clean the part, coat it with olive oil, and hold it over an open flame, I used my gas range, you don't want to apply the heat fast but rather slowly cook the olive oil until it starts to turn brown then finally black, you have to do several coats, but it turns out a very hard chip resistant surface. It's the same surface you see on a well cured cast iron skillet very deep black. I had to take two or three shot to get it right , wire brushing my mistakes ,and you have to be carefull that you don't let it run by turning often, also don't get it too hot or the aluminium will fall apart!

It stinks like all get out, and I don't know how it tastes, that I'll leave up to you!
 
Glassbead the metal,spray and bake with Gun-coat or ANY baking enamel. You will be satisfied with the results I'm sure.
 
One of the epoxy paint-type gun finishes like Brownell's Aluma-Hyde or Aluma-Hyde II or Lauer Duracoat will do an excellent job.
They were specifically developed for use on aluminum guns and parts and adhere and wear very well as long as its applied properly.

Another option is to have a gun re-finisher like Ford's anodize it. They offer small parts processing for nominal prices.
 
Rcmodel, it's actually an ipod mini that i want to refinish. Being an aluminum cased object that i'll be carrying around with me constantly means that a coating that's suitable for an alloy framed carry gun will also be appropriate for an ipod.

Some good suggestions here guys, thanks.
I'm intrigued by the burned on oil thing, I know that some people use a similar technique to blacken steel chain maille, but it didn't occur to me that it would work on aluminum too.

I'm going to try that on a piece of scrap and if I can't get it to work well I'll get some alumahyde.
 
Anodizing is the only way to go. It is dirt cheap. All you do is go to the auto parts place & buy sulfuric acid 1 part acid to every 4 parts water (always add acid to water) then go to Walmart & buy some caustic soda (sodium hydroxide) (which is used to open drains), two plastic tubs, some organic black dye, & distilled water. The hardware should have some aluminum wire you can use as a electrode. Now all you need is a battery charger set to 2 amps.

Dip into a mixture of caustic soda & water to etch & remove the old finish then with the electrode hooked to the + lead in the acid & the - to your part dip part in. Make sure only aluminum is put in the acid or un intended results will occur. Heat the dye to a about 120-130F & dip in your part if you want the textured look or polish the part first if you want it shiny. Lastly dip your part in boiling water to finish it.

I do suggest your do research this & learn to handle the chemicals before you proceed & use a test piece the first time.
 
Kingmt, that's what I was looking into. I'm reasonably handy with things like that and I do have quite extensive experience working with chemicals, but I don't think I can make it cost effective.
I don't have a battery charger or a piece of lead big enough for a cathode, and by the time I had bought everything I need, I'd have spent 50 bucks to turn my ipod black.

If anyone's interested, sulfuric acid can also be obtained from a hardware store as professional grade drain opener, and rit dye works ok from what I gather. Drano granules are a good source of NaOH to strip old anodizing and prepare the surface for new anodizing, about 1 tablespoon of granules to one gallon of water.
Also, ALWAYS add acid to water, never water to acid...
 
I forgot about the drain opener being a sulfuric acid but does it say the % of the mixture?
 
I honestly don't know. I expect it does say on the bottle what strength it is.

I know it's pretty powerful stuff though. My ex girlfriend (who wasn't the sharpest tool in the box) put a large candle in her dishwasher to clean the dust off it. Her sister called and she forgot about the candle. When she remembered, she opened the dishwasher to find a wick with no candle attached :D
She called me in tears, and when I had finished laughing, I told her to run several hot cycles to keep the wax molten and flush it out.
She said she was afraid of causing even more damage, so she left it and called a plumber.
By the time I arrived at her apartment, the plumber was there. He told her that she should have run several hot cycles through the machine :D and then used sulfuric acid to remove the blockage.
It was pretty powerful stuff, we could hear it reacting violently in the pipe and fumes poured out of the plug hole in the kitchen sink.

I think it's probably pretty concentrated, so it should be ok for anodizing once diluted.
A bulb type specific gravity tester as used on car batteries would tell you for sure, but from what I've read on the subject, the acid strength isn't all that critical for anodizing, in fact a lot of people have reported success with pretty dilute acid. Very concentrated acid can actually hinder the process.
 
FYI, ipods are and have always been made of lucite and stainless steel. I don't know why you think it's aluminum. Regardless, any non-bake epoxy paint will do.
 
In the past, when doing a "show n' tell" type thing to impress "management".
I have glass beaded aluminum parts followed by a spray- can coating of clear laquer.
Might not be durable enough for your application but it's worth a try.
 
Highorder, you're right in that the majority of ipods are made of lucite and stainless steel, but the mini is definitely aluminum, and was available in several anodized colors:
http://en.wikipedia.org/wiki/IPod_Mini

In case you're wondering why I'm bothering to do this with such an old model, it just so happens that the hard drive in the mini can be replaced with a compactflash card, which are now available in 64Gb, so I'll have a nice small ipod that can still hold all of my music.

Navyretired, I'm afraid that because I live in NY, an ipod is the most lethal thing I'm allowed to carry :mad:
 
I would not recommend aluma-hyde. It doesn't stand up to wear at all. I sprayed my aluminum trigger guard on my Howa 1500 rifle and it started peeling and flaking after a month (I didn't even use it before it flaked). Powder coating should hold up well. I work in a shop that ceramic coats rifles and that holds up nicely too.
 
rcmodel
Member



Join Date: September 17, 2007
Location: Eastern KS
Posts: 18,401 Is this a firearm?

If so, an anodizing shop cannot refinish a firearm legally unless they have an FFL.
Click to expand...

This is not true, you do not need an FFL to anodize a firearm legally or finish it any other way for that matter.
 
jimmyraythomason said:
Peeling and flaking are a result of poor metal/plastic preparation not the fault of the paint.
Click to expand...
That's true with most metals, but aluminum is a special case.
Aluminum is so reactive that when a fresh surface is exposed, it reacts almost instantly with oxygen in the air to form a thin invisible layer of aluminum oxide.
This inhibits further corrosion, but also means that paint doesn't adhere as well to aluminum as it does to most other metals that are commonly painted.
If by poor preparation you meant that a special primer for aluminum should be used, then you're right.
 
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