Micah – It seems you’re not getting much help from people who actually know how to age metal and wood, so I’ll give you what help I can. Keep in mind my experience here is limited.
As far as the original finishes go, as Gary pointed out, we don’t really know for sure. I would imagine that they ran the gamut from none to very fine, just as they do now. If you go to your local gun store, you’ll see low end rifles with tool marks on wood and metal, and a crummy finish. On the other end of the spectrum are the high end custom guns with mirror polishes on all surfaces. The old guns would have been the same. So, what are you building? If it’s a rough and ready barn gun, maybe you want to finish it with tallow or beeswax, and leave tool marks on the gun. The other extreme would be French polish on the wood, and mirror finishes on the metal. The best advice I can give you is to start with the original tools and finishes. Once you have a finish, you can age it.
In ageing, you are trying to replicate a natural process, only accelerated. The most popular way to age steel around here is to apply Clorox and cold blue. You can find instructions in the archives. When you’re done, you will have metal that looks just exactly like it has been treated with cold blue and Clorox. But if you want a natural looking finish, you need to age it with natural processes.
The only metal and wood I’ve aged was a hash knife, which was done for friend of mine wanted me to replicate a 100 year old hand forged hash knife for him. Here’s the original, and a couple of copies:
I started by hand forging the metal, and rasping out the handle from a block of wood. The wood was supplied to me by my friend, so it doesn’t show age cracks like the original does. If I were really trying to replicate the original, I would have used cracked wood to start with. I tried several techniques for aging the metal, and the only one I liked is very close to what would happened naturally. Now there’s a big surprise!
To age the wood, I applied a couple of coats of Brown Varnish and let them dry. Then I applied a final varnish coat and rubbed the surface with some very fine dirt. The best source of dirt is the fine dirt in a vacuum cleaner bag. A word of caution – do this in some secret place, and destroy the evidence. You do not want to discuss with your wife why you are getting dirt out of a vacuum cleaner bag.
When the varnish was dried to a tacky stage, I suspended the knife in a bucket with a little salt water in it, put the lid on the bucket and put it in the green house. As a rule of thumb, chemical reaction rates double with every 10 degree increase in temperature, so warmer is better. I don’t know what the temperature in the bucket was, but I’d guess in the 100 degree range.
Ageing under these conditions is rapid. You can let it go as far as you like, but from what you are describing I think a couple of days would be plenty. You may want to card the metal once or twice, just like you would do with browning. You may also want to rub back the stock finish a little in the high wear areas, and apply a little dirt there. Experiment, and see what you like. Think about what happens to the gun during use, and replicate that exactly.
It took me a considerable amount of time and experimentation to come up with this process, but I was satisfied with the results. These aren’t great photographs, but in hand it is difficult to tell the original metal patina from the artificial patina. This is because they were produced by the same process. And, except for the cracks, I was able to reproduce the dirt and wear on the wood handles.
