I know this thread can be applied elsewhere but because I did this to a firearm receiver I am putting it here
I recently tried my hand at type three anodizing. froze a five gallon bucket of ice with a small office trash can in it for the acid to stay cold. you don't want the acid to go above 40° or the oxide cell size growth goes up to where it starts turning into type two. I wanted type three so I needed to keep it cold
I didn't get any before photos of the raw handguard as I wasn't really thinking of documenting it but after seeing some of the results part way through I started taking photos. from my research, 6160 aluminum is supposed to turn gray to dark gray depending on how tall you grow the oxide cells or in other words how long you leave it in. the handguard and receivers where all supposed to be 6160 so I thought making then dark gray would look good
set up my station, a bit of a mess and cobbled together loosely but something that would work.
after running the handguard for about two hours I noticed it was turning goldish color. research indicates that 7075 will do that while 6160 turn gray. hmmm. did the upper and lower LR308 receivers and they turned gold too. the photos of the finished parts look a little more gold then they actually are. probably something with the lighting and camera but they still look pretty good. I was pleasantly surprised, especially if they are all 7075 when I thought I was buying 6160 items
the raw receivers before cleaning them in lye and putting them in the acid bath
this is my acid bath. with the parts soaking up the current
finished receiver and handguard. as I said above. it's not quite that intense with the gold but came out nice. probably should have left the handguard in a little longer to make it match the receiver better
I recently tried my hand at type three anodizing. froze a five gallon bucket of ice with a small office trash can in it for the acid to stay cold. you don't want the acid to go above 40° or the oxide cell size growth goes up to where it starts turning into type two. I wanted type three so I needed to keep it cold
I didn't get any before photos of the raw handguard as I wasn't really thinking of documenting it but after seeing some of the results part way through I started taking photos. from my research, 6160 aluminum is supposed to turn gray to dark gray depending on how tall you grow the oxide cells or in other words how long you leave it in. the handguard and receivers where all supposed to be 6160 so I thought making then dark gray would look good
set up my station, a bit of a mess and cobbled together loosely but something that would work.
after running the handguard for about two hours I noticed it was turning goldish color. research indicates that 7075 will do that while 6160 turn gray. hmmm. did the upper and lower LR308 receivers and they turned gold too. the photos of the finished parts look a little more gold then they actually are. probably something with the lighting and camera but they still look pretty good. I was pleasantly surprised, especially if they are all 7075 when I thought I was buying 6160 items
the raw receivers before cleaning them in lye and putting them in the acid bath
this is my acid bath. with the parts soaking up the current
finished receiver and handguard. as I said above. it's not quite that intense with the gold but came out nice. probably should have left the handguard in a little longer to make it match the receiver better
. I don't mind. none of my firearms are show pieces or beauty queens. 
