Corrosion on Kodak plate camera

[vjuliano]

I have a Kodak Eastman No. 5 5x7 plate camera.
The camera is in great shape except for corrosion on the front door. It looks like it is made out of magnesium, but I am not positive.
It does not behave like aluminum normally does and it is not brass. The corrosion seems to be confined specifically to the door. It is sort of just flaking away in layers.

Since it was getting so bad, (completely through in one of the corners) that I decided to remove the leatherette that was no longer attached, sand it a bit, paint it, and re-glue the leatherette.
That mostly seemed to go ok, but it doesn't seem to have stopped the corrosion, with the paint flaking away and corrosion continuing in some places.

Does anyone have any suggestions on how to stop this? Id really rather not loose the door. I have attached a picture to try and better illustrate the problem.

Any help is greatly appreciated
Thank you

 

[Ron (Netherlands)]

To me it seems an aluminium part; sand off the corrosion and put on a nice thin layer of shellac...

 

[vjuliano]

Interesting idea, I may give that a shot. Thank you