Nice safe. You are in for a challenge.
Getting down to the old finish or retrieving artwork is always difficult. The old safes had a black filler smeared on bare metal. I have read that it was a water based filler but don’t know for sure. It makes sense considering the amount of rust one finds under it. No primers were used. The paint was applied directly to it, often with a brush. The artwork was added and usually a varnish was brushed on top to give a shine and protect the artwork.
The problem is usually the varnish crazes with age and gets a textured finish to it. Sometimes the paint checks and curls at the cracks where it is releasing from the filler. Then when somebody repaints the safe the paint can really bond to the rough finish or penetrate the cracks.
Solvents, scraping, or whatever you can dream up has to be tried sometimes in futility. Often the bond of the newer paint is stronger than the bond of the original paint and it all comes off. Sometimes the protective varnish will tolerate mild solvent for a bit but it depends on a number of factors. A razor blade used scraping backward can work well. Don’t push the sharp edge forward as it will gouge. Heat also can help break the bond of the top layer of paint. Be careful how much heat you build into the surface. Every case is different and all I can suggest is to test in an inconspicuous spot.
On a current project that was repainted many years ago I discovered some original artwork after some careful scraping. Solvents would destroy the artwork almost immediately, especially the gold leaf. It was hard to distinguish the layers of paint and I had to use a large magnifier mounted with a strong magnet and a very bright led light to make sense of it all. After trying multiple tools in a test area I was finally able to recover most of the artwork using a very dull old wood chisel. In fact, I had used it to scrape the underneath of the lawn mower deck! With medium pressure it scraped all the paint off quite nicely. I had to be careful on the gold leaf but even there it worked well although it took several hours.
Other than some sanding damage from when it was repainted, after a little touch up I did recover most of the artwork for a pattern so it will be reasonably reproduced. Not too bad considering it is from 1891.
To recover your large areas will be tough. Another option would be to save the front and refinish the rest trying to match the original finish. Using a satin paint or a flattening agent in gloss paint and creating a textured finish to match is doable. That safe probably had basic stripes on the side and would look fine without. This also is a challenge but I have seen fiberglass hot rods that were painted like they were a fresh barn find with the look and feel of old paint, rust, dust, and bird crap. It took a second close look to see it wasn’t real. Good luck with your project.
