Replicating a Gunmetal Finish on Brass

[Lucius1958]

So: with the imminent arrival of my BC-34 reproducer, does anyone have any good suggestions for reproducing the original finish on it?

As mentioned, I had inadvertently polished the top down to bare brass, in an attempt to clean up what seemed to be some very bad nickel, but was most likely a gunmetal finish.

I have seen at least one compound online which claims to work on brass; but it is only available in amounts of a gallon or more.

Would some of the bluing chemicals used by gunsmiths do the trick? Any suggestions?

Bill

[Curt A]

For darkening steel parts or to give brass a dark bronze finish, use Birchwood Casey Super Blue which is available at gun stores - Bass Pro Shops, Cabellas, etc. or online. Walmart has Perma Blue, but Super Blue works better.

I have used it to "age" metal pieces that I have polished to remove years of crud, but want to look like they match the aged patina of an original machine. Clean the piece first with steel wool or whatever method to remove dirt, etc. then wipe the piece with a cloth soaked in rubbing alcohol to remove any oil or grease. Apply the bluing with a cloth or paper towel and when the piece has reached the desired color, coat it with a light oil to stop the process... It works great on screw heads that have been messed up and need to be fixed.

https://www.birchwoodcasey.com/Refinish ... shing.aspx

[Lucius1958]

[quote="Curt A"]For darkening steel parts or to give brass a dark bronze finish, use Birchwood Casey Super Blue which is available at gun stores - Bass Pro Shops, Cabellas, etc. or online. Walmart has Perma Blue, but Super Blue works better.

True, but I don't want a dark bronze finish: I want a greyish gunmetal finish, which is what the reproducer originally had…

Bill

[Curt A]

Sorry, I forgot that the "gunmetal" finish that Edison did was like a darkened brushed nickel finish. I don't know of any way to re-create that on brass, other than with some type of replating process.

[gramophone78]

Bill, this finish has nothing to do with "plating". There is a chemical used to achieve the "patina" you desire. If you contact a metal artist or a restorer of bronzes, Tiffany lamps, etc.....They will be able to tell you which chemical is needed and where you can buy it.
In some cases, the object requires heating while the patina is applied to the surface.
also, there will be a certain skill involved. In other words.....some patina's require time in order to achieve the correct finish.

Hope this helps.

[Curt A]

Interesting... so this is a chemical aging process similar to gun bluing, but to produce a different color. For example, shiny copper can be aged to a desirable brownish patina by using a copper sulfate solution... Steel can be blued or browned and the browning process requires heating the metal first. This would be an interesting study to pursue. Anyone with knowledge about various aging or patina processes should contribute to this, so the information would be available to restorers. Maybe a new thread for storing and accessing this info in the future?

[Lucius1958]

Bill, this finish has nothing to do with "plating". There is a chemical used to achieve the "patina" you desire. If you contact a metal artist or a restorer of bronzes, Tiffany lamps, etc.....They will be able to tell you which chemical is needed and where you can buy it.
In some cases, the object requires heating while the patina is applied to the surface.
also, there will be a certain skill involved. In other words.....some patina's require time in order to achieve the correct finish.

Hope this helps.

So I have surmised.

I have heard of liver of sulphur, which is used to patinate copper: whether that would produce the right finish on brass is a question…

Bill

[Curt A]

Liver of sulphur is specifically used to achieve a bronze finish on copper. For example: on Tiffany type glass lamp shades, the glass is wrapped in copper foil and is then soldered into place - when finished, you have a shiny silver color from the solder. To create an aged patina, you use liver of sulphur or copper sulfate to achieve an aged bronze finish on the solder joints...

[Curt A]

This may be the formula that you need to produce the gunmetal finish on brass:

Transparent Blue
Ingredients
Sodium Thiosulfate... 60 gm
Nitric Acid Concentrated... 4 gm
Distilled Water... 1 quart
Process
A transparent, dip process patina. A preservative such as paste wax or polyurethane is necessary. May produce a grey blue when tap water is used.

[Curt A]

As with anything, it would be best to experiment on unfinished scrap brass before trying this on your actual parts.

Here is a resource for other formulas:
http://www.sciencecompany.com/Patina-Fo ... 60.aspx#13