Anodized Gun Parts Fading

[Tim Bateson]

I've engraved - "marked" a number of gun parts. It comes out a brilliant white - as it should. However I have one customer for whom I've had to re-run the markings. Seems the marks are fading when left in the sun. Is this normal or as my guess would be the anodization isn't hard enough?
Someone will ask for a picture - I didn't take any. The brilliant white markings had become faded until just barely visible. I re-ran them back through the laser and they are again bright white.

[Mark Sipes]

any chance the customer is applying a stain/ protective finish to the parts? Otherwise I would expect the entire gun to be fading..!

[Tim Bateson]

Following my suspicion, I set one outside today (cloudless day) and the part exposed to the sun sure enough did fade.

[Sandy Henry]

After you've etched thru the anodize layer, maybe the aluminum oxidized quicker than usual. I think it darkens as it oxidizes. - Just guessing.

[Gary Hair]

It's possible you are hitting it with too much power. All you want to do is bleach the dye and not disturb the surface. If you don't disturb the surface then there shouldn't be any oxidation taking place because the underlying aluminum isn't exposed. That's what I've been told anyway and I've never really looked into whether it's true or not.

[Kev Williams]

Well-- Here's some of my experiences with anodizing--

This pic shows portions of 3 anodized control panels I built 4 years ago. For nearly 3 years, they've been sitting outside, against the house, facing east, right next to our water hose. They're there on purpose for UV and weather testing. There's a house behind ours that shades part of the morning sun, but they get maybe 3 hours of full sunlight every day. As you can see, one panel has faded almost back to it's raw aluminum state, while the other 2 have fared pretty well. They haven't changed much in the past year.

But the etching on all panels looks just like the day I did it...

So why are your guns fading to back to black? Like Gary says, could be you're burning the anodizing down to bare metal. However, if that's the case, I'm not sure why you could bring the etching back to white, unless your laser has the power -- My 40 and 25 watt lasers will NOT etch bare aluminum, however, my 80 watt Triumph will. Also FWIW, the panels I have made have enough anodizing on them that I cannot burn thru it with my 40 watt'er no matter how hard I try. But I have run into black anodizing several times that is so light that it's hard NOT to burn thru it. And it looks terrible if it does, because it's not consistent. Your sig says you're running a 35 watt machine, so...? Could be the dye in the anodizing is leaching, regardless of whether you're into bare metal or not. Anodizers can use pretty much anything they want as dye, I've heard that one shop around here has used RIT clothing dye. Can't help but think that would leach! But- I don't know for sure?

All I do know for sure is that I've etched maybe 5000 black anodized plates, panels or other parts in the past 11 years and while I've seen the anodizing fade, I've never seen, or had anyone tell me that any etching I've done has ever faded.

fadedpanels.jpg

[Dan Hintz]

The marks cannot be fading back to their original anodized color... the chemistry simply doesn't support such a thing. What is likely happening is the anodized layer isn't of high enough quality, and you're seeing what oxide layer is there begin to deteriorate, allowing some of the original metal color show through. If that's the case, the only real solution is to request a better quality anodizing.

[Mike Null]

Anodized aluminum will fade in UV light. It's not likely that it is a poor quality anodizing job given that it's on a gun. But some anodizers are not careful with their process and quality can be an issue. I've rejected many anodized aluminum parts for that reason.

[Dan Hintz]

Anodized aluminum will fade in UV light.

Just so there's no confusion, I'm not suggesting the anodizing itself won't fade with UV, I'm saying the laser mark cannot fade... the only thing it can do is take on more of the characteristics of the base metal.

[Tim Bateson]

1. As some have suggested - No I would NEVER laser through the anodization - unless requested to do so. That isn't the proper way to laser anodized parts.
2. What is odd is the marking - which was a bright white after the 1st laser, is now just barely noticeable & turns white again when I re-laser it. This is repeatable by placing it in the sun. I've tried rubbing & chemically wiping it after I laser & see no difference, just exposure to the sun seems to cause this fading.

I'm going to talk with my customer tomorrow about the "possibility" of bad anodization. This is sticky situation as it'll be one contractor blaming another. These parts retail for $,$$$ each & I have done hundreds of them, so this issue has got to be resolved. I do know this is their 2nd contractor to provide anodization, so they won't be anxious to have to find a 3rd.

[Scott Shepherd]

There's more to this story Tim. As Dan stated, it's not physically possible for something like that to "fade". It's black die, it's not hard anodize, it's just decorative. Once you bleach the color out of it, there's nothing there that could turn color. I don't even know how "bad anodizing" could cause it. It's dye. Once it's gone, it's gone.

Now, if it's hard anodizing, I could understand it. You won't mark hard anodizing with your laser. If you tried, you might get a white mark, that could then fade back to darker, because you'd be "frosting" the top but not penetrating the hard coat, but when light hits it, it would be fading your "frosting" of the top coat, but I don't even think that's possible. I was going to suggest it was something other than anodizing, some other similar process for the guns, but you seem to be in the loop with the customer and know that it's just anodizing.

It would be like something that was painted red, then you engrave it and then you say the area engraved is turning reddish again. It's just not possible. There's something else going on here.

[Dan Hintz]

For clarity... are these "gun parts" firearms or paintball pistols? I'm assuming the latter but wanted to verify...

[Tim Bateson]

Gun parts anodized Black, Gray, Green, or Red

[Mike Chance in Iowa]

Just throwing this idea out there as it doesn't hurt to ask. Are they cleaning the gun with any type of oil or something else that could possibly be changing the color?

[Tim Bateson]

Just throwing this idea out there as it doesn't hurt to ask. Are they cleaning the gun with any type of oil or something else that could possibly be changing the color?

That was my 1st thought too, but no.