This question is slightly off topic. But I need it for a cabinet.
I've seen this in the past - but cannot remember how to do it.
There is a way to make new brass components look like antique brass. The component is put into a chemical and rinsed off, or slightly rubbed with steel wool during the process. I think the chemical was muriatic acid.
Just wondering if anyone knows what chemical is used and what the procedure was.
Pat
This is just one of many sites on the subject. If you need more or sources of chemicals just beep.
What does "antique brass" look like ? You trying to age it just a little, or really change the colour ?
You need to experiment on all these patina recipes, and watch your technique. They're very sensitive to metal composition, surface cleanliness and precise details of the technique like concentration and timing. Some recipes require vigorous boiling for an hour or so, and the acidic fumes aren't a good idea in a kitchen. Often the same recipe gives a range of colours from either acid or alkline solutions. For repeatability you'll need a pH meter or test papers.
Also be careful of finishing techniques afterwards, particularly to neutralise whatever you have used (especially with chlorides). Otherwise a beautiful patina might develop into ugly lurid green crystals.
A simple source for them (mainly the heavy duty patinas) is to get made-up solutions from suppliers to the stained glass trade or sculptors. The chemicals you need are usually metal salts that aren't easy to find and are very difficult to buy in a sensible quantity. You'll find them in a school-level chemistry laboratory, but not often in industry (except metal finishing).
_The_ book on colouring non-ferrous metals is "The Colouring, Bronzing, and Patination of Metals"
but it's expensive.
Tim McCreight's "Color on Metal" is cheaper and more fun to read, but less encyclopedic
Don't expect to achieve much with just the commonplace workshop acids. If you use them dilute they're more likely to clean things. If you have them concentrated on brass, you're likely to preferentially dissolve the zinc and turn it a coppery pink. Putting a strong colour on brass needs salts of something other than copper or zinc, so that needs adding metal salts from your solution. Some of these, like copper acetate or nickel sulphate can be significantly toxic.
You might (possibly) be able to find a Japanese patination agent called rokusho. This is an intermediate step for many varying patina recipes, based on different recipes with household ingredients such as vinegar or radish paste. It avoids shopping for a dozen different chemistry lab compounds..
There are three favoured recipes for "antiques trade" patination. One is darker, slow to use but quite easy, one is more authentic looking (slightly greenish) but both need a mixture making up first. The last is very simple, but has a slightly less authentic yellowish colour.
#1
copper sulphate 20g zinc chloride 20g
Grind the ingredients in a pestle and mortar, then mix with water to a paste. Brush on, allow to dry completely (at least 12 hours) then wash off with water. Allow to dry for another 12 hours, then repeat as necessary. It will then take a week to dry completely, during which time the colour may be slightly affected by light. Then wax it.
#2
copper carbonate 45g copper acetate 15g ammonium chloride 15g sodium chloride (salt) 15g cream of tartar 15g
10% acetic acid (spirit vinegar) 120mlMix this all up in a large glass jar and stir. Stir every few hours and allow a day or two before using. After a few days it can be stored in a capped jar, but don't seal it tightly as it may still generate some harmless gas.
If you're using vinegar, get some pickling vinegar which is usually marked for concentration. Adjust the quantity accordingly. Varying the acid content (between 1/4 and 4x these amounts) will vary the colour. More acid is more yellow-orangey rather than brown.
You can substitute ammonium carbonate for the copper carbonate, which gives a much darker and more greenish patina.
Apply the solution with a brush and work it in evenly and quickly. The colour change takes minutes, while you're handling it, and can be stopped by rinsing with water. Dry overnight and wax.
This process works on old brass, or on some modern cast brass. It's sensitive to metal composition and doesn't work well on modern rolled sheet brass.
#3
Take a sealable plastic box (Tupperware or similar) and 1/2 - 3/4 fill it with planer or handplane shavings (not sawdust). Use a non-resinous softwood, beech, maple or something inoccuous. Avoid darker or tannin-rich timber. Ideally the box is transparent enough to let you judge the colour.
Place your components into the shavings, and well separated from each other. Tying them all to a length of baler twine will help later. Then pour in a few teaspoonfuls of strong ammonia (.880 ammonia, rather than 26%), taking care not to spill it directly onto the parts and seal the lid. Working outdoors.in a full-face respirator is a good idea here.
Now watch the colour changes. Shake the box gently to avoid shadowing the parts by contact with the shavings. Don't splash ammonia onto the metal - this is a gas process, not liquid.
After a few minutes, open the box and extract the parts. Shake the shavings back into the box and re-seal it deal with later. Wash the parts with water, dry them and finally wax them.
Dispose of the ammonia by dissolving it in an excess of water and pouring it onto the garden or down the drain.
Muriatic acid is just dilute hyrdochloric acid. What you're looking for is something like "liver of sulphur", though there are other things that will turn sterling silver, brass and bronze dark brown - almost black. If you have a lapidary place in town they'll have what you need. It's a surface treatment so it will rub off with wear. Wire brush the metal to give the patina some low spots to sit in.
charlie b
there are a bunch of different kinds of brass. they all act differently. some of the patina recipes call for fuming in ammonia to get blue-green.
Thanks Charlie...
Pat
That's different.. Never heard of that before...
Fri, Dec 3, 2004, 10:03am snipped-for-privacy@home.com (SawDust) wonders: Just wondering if anyone knows what chemical is used and what the procedure was.
In the Army, you just needed to polish your brass, get the lacquer off, and use Brasso. Then not polish it for a day or two, and instant antique.
JOAT Be who you are and say what you feel, because those who mind dont matter, and those who matter dont mind.
- Dr Seuss
A significant component of Brasso is ammonia. What you're seeing isn't too far from recipe #3
Hi Andy,
I know Brasso well. Didn't realize ammonia was in Brasso.
As for recipe #3 "you totally lost me". Is this in a cook book somewhere..?
Pat
Sun, Dec 5, 2004, 1:19am (EST+5) snipped-for-privacy@codesmiths.com (Andy=A0Dingley) says: A significant component of Brasso is ammonia. What you're seeing isn't too far from recipe #3
I don/t recall ever reading the ingredients. Still, it'd be better than screwing around with ammonia, in my book.
JOAT Be who you are and say what you feel, because those who mind dont matter, and those who matter dont mind.
- Dr Seuss
In the huge great posting I made on this thread a couple of days ago ?
Blame it on selective brain function. I now recall seeing your original post. Not sure why I missed it. I must have been browsing the NG's and sleeping at the same time.
Thanks for the URL. That was a big help.
Pat
On Sun, 05 Dec 2004 04:44:20 -0500, SawDust calmly ranted:
Hose some of that sawdust out of your nose, Pat. You cannot miss it.
Yeah, Andy, whose recipe?
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Being more or less color blind, I almost learned to recognize "green" in the Army, the above included.
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