HEating Black annodized aluminum turns gold?

[hirby]

So I had an old black aluminum annodized flashlight that I found in a box with the AA batteries corroded into the tube. The batts had expanded and glued themselves against the walls. An attempt to push them out with a screwdriver only pushed out the center of the batts but left the casing still stuck in the tubes. Getting sick of this I whipped out the propane torch and burned out stuff making the batt casings stick to the walls.

Well in the process of getting really hot, all the black turned a lovely bright shiny gold. Figured a color change would occur from the heat, but gold? Actually looks very nice and even bright gold.

Edit: Pic added! The body used to be black annodize like the rest of the flashlight.

 

[Zot]

pics?

 

[ACMarina]

That's VERY interesting! I wonder if there are mirror colors for other anodization colors..

 

[greenLED]

My Pila GL3 has a slight emerald-green to it's black anodizing.

Could it be that you "cooked" some chemicals from the batteries onto the light? Have you tried scrubbing the "gold" off?

 

[hirby]

It wasn't the battery chemicals. That was only on the inside. It was the actual annodizing turned gold. I watched it change colors from one side to the other as the aluminum got hot.

Think I'm gonna try it on the body of my black Surefire Z2 to see if it changes color too. That way I can claim to have the only gold Surefire Z2 !

 

[hirby]

Update: Must have been the type of annodizing used on that particular flashlight. I tried heating my black Z2 and it's still black as ever :-(! Was hoping for a pimp Z2, but no luck.

 

[ACMarina]

Hirby, what kind of light was it??

 

[Stillphoto]

I can only imagine that it was a type II ano job. That and that maybe it was just a freakish occurance, although I had a light stand once that was made in china...It had been left in the back of my truck for some time, exposed to the summer sun day in and out. The no doubt inferior (it was a crappy stand) black type II anodizing job had faded to a brownish-gold color only on the side facing the sun. Come to think of it, I've seen photograph strobe reflectors that had changed color in a similar manner due to exposure to a hot light source for an extended period of time.

 

[tvodrd]

Type 2 black dye will fade eventually in direct sunlight. It usually goes through a light purplish on the way. I've seen heat kill it too. Your mileage will vary! Black and gold seem to be the most stable Type II, Class 2 colors, and I've used them at work for 30+ years. Kinda my "trademark" for equipment I've built for myself and employers over the years.

Larry

 

[IsaacHayes]

I wonder if whats left of my minimag would do that if I hit it with a torch... Same thing happened, batteries stuck inside. So I cut off the tail cap section that was fused and now I have a tube sitting around heheh.

 

[hirby]

Hirby, what kind of light was it??

It's an old DUO Lite. The big head you see with clear side can be slid forward to make it an area light. I replaced the original funky xenon lightbulb with a old 3-watt luxeon I had sitting around and direct drive it with the 2 AA batteries. To turn it on your rotate the head 30 deg. It's not very bright obviously, but brighter than the incan bulb and makes a fun get-in-bed-and-pretend-to-sleep light for the kids.

It was actually made very well and in Venice, CA USA.