Have any of you datable examples of passenger car sound deafening materials? What they were using, when? and where?

"Deafening?" It sounds like material to make things louder! :-)
I think you mean sound deadening materials.
In the heavyweight era they used horse hair.

I've also found horse hair insulation in some of the old Southern Pacific Harriman cars. Presumably it was the original material used in the cars.

I'm not sure what the primary purpose was. I'm going to guess it was mostly intended for insulating the cars for heating purposes, and any sound insulating properties that it provided were secondary.

Pullman widely specified a paint-on coating called "Dednox" on lightweight streamlined cars. Car specifications available from the Pullman Library at the Illinois Railway Museum would tell you exactly where in the car structure this coating was applied.

Porter Paint Company applied for a trademark on the name "Dednox" in 1958, describing it as "PAINT TO BE APPLIED TO THE SURFACE OF METAL FOR SOUND DEADENING PURPOSES".

Deafening was a perfectly acceptable term at least in the 1800's. A layer of tongue and groove boards attached to the bottom of the sills is called the deafening ceiling. The space between the deafening ceiling and the inside floor was sometimes filled with sawdust to reduce noise in the car.

Damping sound is a very similar problem to that of containing heat like thermal insulation. The need is to adsorb the energy in the sound and convert it to heat, or slow down how fast is moves through a space. Or you can try to reflect it away from the "quiet space" you want to create.

Horsehair (a natural version of modern fiberglass), sawdust, cork, lead, dense paints (or modern thick plastic tapes) all try to do the same things; absorb the sound, or direct it to someplace else.

These are some of the modern solutions to an old problem;

https://www.mcmaster.com/#sound-absorbers/=15ac5yv

I have read that the structural steel in some railroad passenger terminals (Central Terminal in Buffalo NY on the NYCRR) where intentionally isolated from the concrete ground foundations with a "state of the art (ca 1929)" layered "washer" of alternating sets of lead sheets and cork sheets. This was an early attempt to keep the noise from the trains from entering the waiting rooms, etc, of the "public places" in the terminal.

Seems like the early solutions are along the same lines as the modern solutions. The guys that like to "soup up" their hot rod cars with big speakers/amplifiers have used the same ideas.

Cheers, Kevin.

Thanks everyone. The literature suggests that sawdust and shavings had been replaced by mineral wool by the 1890, due to fire danger. I am hoping to learn whether there was a sequence of accepted/recommended materials in hopes of being able to date work on a particular car. I suspect I hope for too much--local availability and economy undoubted trumped current recommended practice.

The various "paints" and other sound deadening coatings were usually full of asbestos and used to prevent "drumming" of duct work and sheet metal applications.

T7

The same technique was used a decade earlier for the New York Central's "Terminal City" development (office buildings, hotels, etc.) built over the underground trainshed of Grand Central Terminal in Manhattan, and much of it is still in place 100 years later.

-Philip Marshall