Oxidizing Aluminum

[Brian Robison]

Any one ever do this?
I have a bottle of Aluminox from JDS but I have no instructions. I looked at the world wide web until I reached the end of it with no luck.
HELP!!!!!

[Dave Jones]

I've never done it. All I know is what I've read. That it is applied to freshly cut mechanical engraving to darken the raw metal.

[Brian Robison]

Thanks Dave,
Just hoping it will work with the laser too. Looks like as long as it's exposed aluminum it would work but I see no reference to laser engraving, only mechanical.

[Dave Fifield]

As far as I can tell, oxidized aluminum is more commonly known as anodized aluminum. In its pure form, it's kind of white-ish/grey-ish boring looking surface. Normally it's then dyed to whatever color you want, then it looks great.

You can laser engrave the surface of anodized aluminum. The CO2 laser does two things. One, it burns out the dye in the aluminum oxide layer, and two, it takes off a couple of thousandths of an inch of the anodized layer. If the anodizing isn't very thick, you can actually remove it completely down to the bare shiny metal. Thus, the finished look is either kind of white-ish/grey-ish, or shiny aluminum (which looks fantastic!).

HTH,

[Jeanette Brewer]

Thanks Dave,
Just hoping it will work with the laser too.

Brian,

One of the beauties of the laser mark on metal is that it will not oxidize over time. The flip side of that is that you can't oxidize it the way you can mechanical engraving.

I'll have to leave the "why does it work that way?" to the chemistry experts. I just know that's the way it is.

[Brian Robison]

Well, that's not what I wanted to hear!

[Dave Jones]

Yeah, my understanding is that material is not for use with a laser. If you want a black mark on clear aluminum, use CerMark. If you want a grayish white mark on black or colored anodized aluminum you need nothing but the laser.

[Brian Robison]

It's not anodized and I'd need more power than 25 watts to do Aluminum. Had I known that when I bought it I would have gotten a more powerful laser.

[Eric Allen]

Brian, can you sacrifice a part to testing? I have a possible solution, but I haven't done it on Al. Ah yes, and how big is the part?

[Brian Robison]

The part is small, 4 inches long 1/2" diameter.
I'm hoping to fix the parts I've used for testing so
far by touching up the paint. Paint looks bad anyhow.
It a military part so it's that olive drab flat paint.

[Eric Allen]

Wish I had some extra AL laying around to play with, I'd like to try this process on it. There is an etching process, and you can use different compounds to pull it off, in steel for certain but AL I don't know the end result. The worst possible outcome is the removal of the paint, so if you want to take the chance: Try mixing up a small bowl of hot water with salt. Using salt you should do this outside, there is a small chlorine risk, though you'd probably get more standing by a swimming pool. You can use sodium carb, or bicarbonate, but I don't remember which, the salt I know works. Mix in as much salt as the water will take in. Take either a 9volt battery or charger/power supply and hook up the positive to the item to etch, the negative to a small piece of copper (like 12gauge wire) and set it near, but not touching the piece, and hook up the negative. If you use an adapter, sometimes it's good to put a load in line like a little computer fan or something to keep the load regulated. Anyway, this process will etch steel, stainless, and I think brass, so it could be worth a shot. If the leads are on backwards it's more likely to remove the paint if I remember right.
It's a cheap, easy test, and if it works, it should alter the area that you used the laser to remove the paint from. This only takes around 5 minutes or so on steel and you can remove the parts and put them back in with no ill effects. Oh, just so I'm clear, that power supply MUST be DC output. And best of all, no indexing

[Mike Null]

Brian

To oxidize aluminum you must remove the surface to get to the raw aluminum. Regardless of the power of your laser it will not do the job.

I have used a mask and sandblasted both aluminum and brass then oxidized. You can also used something as simple as a pantograph to mark the numbers or you can make a stencil and paint on the numbers.

[Stephen Beckham]

Can I request that you video your attempt if you try Eric's suggestion.

I like the sound of it and bet it would make a great video...

Either instructional or for submitting to the Darwin Awards

[Brian Robison]

Thanks for the input. I did a test last night on the oxidizing. Scratched with a chisel the aluminum oxidized, lasered it didn't. If it was a few parts I'd try something but it's 3500 parts.

[Mike Null]

Brian

What about finding somebody with a pad printer. They would probably do it for $.10 each or less.