Shutter leaf stainings?

[Wayne Crider]

Looking at my 150mm B&L barrel lens I see what may be the bare faint evidences of what may have been a staining or anodizing of the blades. Now they look basically slightly tarnished and a little too bright. I suspect that contrast is diminished, but what can you expect from a lens as old. My late model Fuji on the other hand has nice black blades that look almost coated in a respect. I was wondering if there was a period of time where blades started appearing stained/anodized or coated or was it the norm?

[Robert Hughes]

Typically, iris leaves were made of carbon steel and sometimes coated with a thin film of oil for rust protection. As a lens ages over the decades, off-gassing of the rust protection may cause an oil film on internal glass elements, which of course reduces contrast.

[Wayne Crider]

What then is the coating on the newer lenses?

[Glenn Thoreson]

Shutter blades have been made in all sorts of finishes. Kodak made some that were bare steel. Most of the old ones are dipped in a chemical bath similar to gun blueing, to help prevent rust and corrosion. The newest method seems to be more like an anodizing process. If your B&L concerns you, you can touch it up with a Q-tip and some gun blue. I doubt the defect would have any serious effect, though.

[GPS]

If you wanted to blacken them again you could do so with those indelible pens - it's easy and will last long enough before you need to renew the blackening.