What plating was used on the controls/plates of a 1924 RB Series B 3 1/4 x 4 1/4 format?
I have never seen rust and discoloration like this. Was it tin or another iron/ferrous coating?

This camera does not have paint and its not silver.

Graflex and Speed Graphic cameras through late 1920's, used a chemical process to color all exposed metal parts dark grey. I believe all the metal parts were brass. In period catalogs the company referred to this as "oxidizing". Exact chemistry of this process has (a.f.a.i.k.) been lost in sands of time.

In late 20's-early 30's, Folmer Graflex Corp. started using dark grey paint instead of oxidizing process.
Nickel, chrome plate, and black paint first appeared on (1938) Miniature + (1940) Anniversary Speed Graphics, and first-version (1941) Super-D Graflexes.

There were a lot of different chemical methods of colouring brass used in the old days. I have a copy of the Scientific American Cyclopedia of Formulas (1910) which has two pages worth of recipes for making brass black, brown or blue as well as other colours. All of these seem to involve toxic chemicals, and some require heating the part first. Old copies of Machinery's Handbook (and I imagine other vintage metalworking handbooks) have some similar recipes. I've seen chemical blackening agents for brass sold quite recently in model railway supply stores, but I've never used one.

Yes, the model rr hobby has known about brass blackeners for years, but I've never tried it. A good hobby shop would be the place to look should I ever need such a product.

I was looking online between the initial post and the first reply and found some metal toning chemicals for a reasonable price but did not order any as there was no set color but several colors for one chemical set. The tone you get depends on the time in the chemicals.

Now that I have seen the replies I'm holding off on replating/toning. I could not find any gun metal gray or flat charcoal gray spray paint locally so I painted the lens/focus frame satin black.

The focus knob, focus plate, wind plate, and tension plate I soaked in CRC Quick Dry Electrical Contact Cleaner then rubbed them down with a cotton cloth. 99% of the corrosion was removed and they look acceptable.

CRC products are the best. CRC-556, now sold at hardware and auto supply stores under the name Power Lube, has been used by mechanics for years. Do not mistake it for WD-40; the Power Lube is a true lubricant, not a drying agent (WD = water dispersant).

William Hallett wrote:

There were a lot of different chemical methods of colouring brass used in the old days. I have a copy of the Scientific American Cyclopedia of Formulas (1910) which has two pages worth of recipes for making brass black, brown or blue as well as other colours. All of these seem to involve toxic chemicals, and some require heating the part first. Old copies of Machinery's Handbook (and I imagine other vintage metalworking handbooks) have some similar recipes. I've seen chemical blackening agents for brass sold quite recently in model railway supply stores, but I've never used one.

-I stand corrected, the formulas are not lost!

45PSS wrote:

I was looking online between the initial post and the first reply and found some metal toning chemicals for a reasonable price but did not order any as there was no set color but several colors for one chemical set. The tone you get depends on the time in the chemicals. Now that I have seen the replies I'm holding off on replating/toning. I could not find any gun metal gray or flat charcoal gray spray paint locally so I painted the lens/focus frame satin black. The focus knob, focus plate, wind plate, and tension plate I soaked in CRC Quick Dry Electrical Contact Cleaner then rubbed them down with a cotton cloth. 99% of the corrosion was removed and they look acceptable.

-To add: Appears Graflex changed chem's used to treat brass during WWI. My earliest unrestored cameras (good finish still intact) are 1912 'postcard format' top-handle Speed Graphic and '15 Auto Graflex Jr. Oxidizing is dull (not matte) very dark grey (not black).
After WWI, finish is dull (not flat) black. Then they went to dull-finish dark grey paint sometime between '27 and '33. I'm sure there are original cameras out there wearing both painted and oxidized parts.
I'd like to try oxidizing some parts using original formulas. When restoring cameras, have found old factory oxidized finish impossible to duplicate using modern methods.
Good luck with your restoration!

About 30 years ago there was a brass blackening product popular with the Model Railroad enthusiasts that contained a selenium compound. This may not still be available as extremely small amounts of selenium absorbed by a woman during the earliest weeks of pregnancy can do serious damage to the baby.
BTW I'm the other Henry not the one from Allentown who posted an earlier reply.

Graflex described the brass in 1904 and 1913 catalogs as; "... oxidized in gun metal finish". In 1923 and 1926 catalogs this became; "... exposed metal parts are of silver-plated brass, richly oxidized to a dull, matte tone".
Perhaps expense of silver plating is one of the reasons Graflex went to grey paint around 1930?