My 1925 Stanley is starting to come together. Can someone advise on the proper method for restoring door handles? The underlying rust has expanded and broken up the black (now brown) substance that coats the handles. After removing the old plastic and bead blasting the handles, what does one put on to replace the old plastic material? Does anyone do this professionally?

Looks like a job for Kwik-Poly to me. It's brushable, sandable, and paintable.

I bet that isn't plastic. You might look into celluloid or a nitrocellulose type material. Could possibly be a type of Bakelite but looks too glossy in the broken areas.

My first question is along the lines of Bob Kerr's: check the material composition. Think about what material they would have access to in the 1920's. Is it possible this could be thick and aged leather, like they wrap around lap robe bars in a touring car?

The Kwik Poly suggestion is also good. Kwik Poly can be tinted using dry pigment, never liquid color agents. Dry pigment is available on some web sites. I've used powder coat colors successfully as a replacement for dry pigment. Make sure to get a nice uniform color mix in part A before adding part B and again, mix thoroughly. I would be concerned about maintaining the thickness with Kick Poly, though it can be sanded and buffed. I would think tinting is better than a surface coat of paint, though a little harder to do. I've never tried spraying Kwik Poly. The set up time would be hard.

Here's a thought, what about sprayable pick up truck lining? It has a plastic-like composition. One brand name I know is Rhino Lining. It is relatively thick (1/16 to 1/8 ich), intended for outside/outdoor use, spayable, and can be masked off, and can be tinted. Check with local dealers and perhaps they'll shoot the handles while doing a regular customer job.

Chris