Brass patination

[mtgraver]

Hey there folks,
I do some old gun and particularly sword restoration and coloring brass to the brownish green color is difficult. I can get an acceptable color (blackish) but not what I'd like. I believe someone wrote in a reply a week or so ago about a brownish color using ?baking soda and water? I know there are some nasty chemicals one can purchase for the color and many different recipes. Does anyone have a home recipe that works in a short period of time? Can't wait years. I've used super blue, brass age, liver of sulfur. My results have been quite acceptable for the collector but I continue to search for my own satisfaction. Dirt and grime can cover up repairs but doesn't perfect the technique.
Anyone going to Baltimore antique gun show this weekend in Timonium MD?
Mark
www.MarkThomas-graver.com

 

[Sam]

Mark: Back when I worked at New Orleans Arms, Lynton McKenzie told me of a way to brown brass that is the best I've ever seen. Whether it's the color you're looking for I don't know, but I'll describe the process I used on a few projects.

I used aqua ammonia which is some really horrid stuff. It seems to be a jillion times stronger than household ammonia. When I first got a small jug I uncapped it and took a whif, and it about knocked me to ground. God forbid if you spilled or broke a jug inside your workshop or home. It's nasty nasty nasty stuff, and you have to get it from a chemical supply house. If you decide to use it, read up on it and make sure you handle it according to instructions.

I poured some aqua ammonia into a small tupperware/rubbermaid container, placed a riser made of plastic or glass inside, placed my clean brass object on the riser so it wouldn't get wet, snapped the lid closed and let the vapors do their thing. I don't remember how long it was (30 min?), but the result was a gorgeous, smooth, perfect brown color.

I once engraved a necklace made of brass sheet, gold plated it, then masked everything off with clear tape and cut away the tape to expose the background areas of the engraving, then bead blasted the plating off of the background. Then it went into the aqua ammonia vapor chamber for coloring. The end result was a striking gold necklace with bright gold scrolls and bead blasted brown background. Totally killer.

~Sam

 

[DanM]

You might want to try Baldwin's Patina,it's availible from Reactive Metals and safer than most patinas.There are many alloys of brass so it will be trial and error to get the color you are looking for.But the process is simply wiping the patina onto the brass with a wet cloth till you get the darkness required and then rinse with water.

http://www.reactivemetals.com/Pages/rmspat.htm

 

[Bama]

I had a small bottle of nitrc acid in my tool box that leaked while in transport from a seminar one time. It was a week after getting back before I opened the box to get at my tools. All the steel surfaces had a layer of rust on them and the brass parts in the box had turned dark and had started getting green corrosive build up that you see on old brass. You can get this in small quanties and it is fairly cheap.

 

[JTR]

Here's a couple more places!

http://www.sciencecompany.com/patinas/patinaformulas.htm#26
http://www.sculptnouveau.com/

John

 

[RoycroftRon]

You could try 1/2 a tablespoon of ferric nitrate to 1 liter of water.

With plenty of good ventilation, and maybe even a good respirator with acid gas cartridge filters (may be overkill but you can't be too safe)

If you can, flame heat the material for a few seconds then mist the solution using a spray bottle and repeat until a desired color is achieved.

This forms a nice caramel brown on copper and usually a nice aged brown on brass/bronze. Temperature is a major factor, as is the even coverage of solution on the material.

 

[Powderhorn]

Sam;
That stinky stuff you were talking about is now known as Ammonia Hydroxide.

 

[KCSteve]

One of these days I have to try a trick I read in a reference book. It noted that if you heated copper red hot and then quenched it in boiling water it would turn a nice red color.

 

[RoycroftRon]

I have done that red trick. Coating it with a boric paste flux (like otto flux or handiflux) and burning it almost completely off and then quenching in hot water seems to produce pretty consistent, and good, results. You really need to get that metal to glow.

 

[mtgraver]

Thanks guys, I'll try some of your ideas. I've tried household ammonia and fumed the piece but got the verdigri green, which is nice but not real durable. The carmel brown is what I'm shooting for in most cases with a hint of verdigri. I've perused some old recipes in some old books but the archaic terms can be confsing at best. Trying to get some of the chemicals can be trying as well. I appreciate your time and references.
Mark