You're not suppose to apply Alodine to magnesium .
So, why would you do that? Are you doing destructive testing?
IOWs you do not know the test to identify a mag alloy.
Do you know why Alodine 1200 is not to be used on Mag. alloys?
For the rest of you folks that would not be expected to know elementary A&P stuff. Placing a speck of Alodine (Chromic acid) on a mag. part will turn it BLACK telling you it is a mag alloy. Then you would know to use a chemical conversion coating such as DOW #19 o the part.
These rudder pedals were tested and they did not turn black when Alodine was applied after being cleaned in my bead blast cabinet using Glass bead. Which worries Glen, because he doesn't know that when a glass bead strikes a solid surface it shatters and turns to dust. and is removed from the cabinet by the circulating air filter. Glass that is used is never recycled to strike any surface again.
This why I use a glass bead. I've explained this twice to Glen but he simply does not comprehend the process.
The reason the pedals advertised in the ad posted here can't be welded is simple, The alloy Cessna and Continental use is a Zinc alloy. When you try to weld it it, the zinc will fume out of the molten puddle, thus the weld will be a different weld alloy, which will expand and shrink at a different rate, causing cracking beside the weld bead, as it is heated and cooled, This is why the oil sumps for the 0-300-A thru D are getting difficult to find. they corrode and can't be welded.
You can depend that these pedals will be repaired properly, if they can't they will be thrown away and new bought.