I recently purchased a Speed Graphic, Ser No 851988. It does have the graphloc back and I guess it's the newer Xenar 135mm lens. The bellows appear to be in excellent condition and with no light leaks. In reading many of the posts here, I get the impression that not all bellows were leather. Can anyone tell me what this unit has for bellows material from just the ser. no? The external appearance of the bellows is quite shiny and black of course with a dull interior. Are there any tests to show what the material is and how it should be cared for? Thanks for any and all replies.

Any camera in the 850,000 would be a Pacemaker and all pacemakers used a vinyl bellows. I followed Ken Hough's suggestion and use lemon pledge. Armour all is okay but can attack the glue.