Has anybody got a recipe for chemical blackener? (To blacken brass and other metals)
{Havard Houen}

Check with your local model railroad store there is something sold for them already mixed.
{Graham Mansell}
I use gun blue, in north America sold by companies such as Hopps and available at hardware stores and most sporting goods stores. Not sure were you would get it in Norway. I can't remember precisely but I think the main ingredient is phosphoric acid. The train modelers have a similar product available as well. I took a quick look through my Walthers catalog but couldn't find it right off. I think it is called Blacken it or something of that sort.
{Graham Collins}
"Blacken-It" (or the equivalent) is very effective on brass -- and, as I recall, on copper. It does not work on aluminum or stainless steel.

I learned the hard way that any surface to be blackened must be very clean if a mottled appearance is to be avoided. I always rub down my parts thoroughly with fine steel wool and mineral spirits to remove all traces of oil and oxidation before applying Blacken-It. Any glue on a part's surface will prevent uniform coloration, of course, and must be avoided at all costs.

I always immerse the part in Blacken-It if possible (or keep the part thoroughly wetted) to ensure uniform coloration. Different effects ranging from mild blue-black to dead black can be obtained by varying the amount time that elapses before the Blacken-It is washed off. The resulting finish becomes very dull (i.e., "flat") if it's allowed to progress to the "dead black" stage, but it can be polished easily to a partial or rather bright sheen by rubbing gently with an old tee-shirt.
{Charles Metz}

Here is the list of compounds found on the label of a bottle of Blacken-It: Denatured alcohol, selenous acid & dilute copper chloride/copper carbonate. The copper chloride explains the light blue color.
{GRN BERET}
I finally found my bottle of chemical blackener (Hobby Black No. 1) and the two main ingredients in it are Selenium Dioxide and Methyl Alcohol. There is also a big warning that they are poisons without antidotes and that vomiting is the only treatment if swallowed. Great if you don't have small children or barflies around.

This stuff does work on everything but aluminum and stainless steel.
{Cookie Sewell}

I get good results by brushing coats on, usually several, that will darken the brass gradually. Dipping the metal in the stuff often doesn't work.

Over the years, I noticed that different brass fittings (perhaps made of different grades of brass?) work better or worse with chemical blackeners. The best blackener I've ever used comes from a jewelry supply house.
{Kerry L. Jang}

I have had success with most of the available chemicals. My approach however is to do it in steps. Dip it once to get a bronze patina. Buff it with a rag to get off any loose stuff. Then dip it again, and repeat this until you get the shade of black you want. I too found that if you just soak it for a long time it just builds up a big thick sooty mess.
{Ben Langford}
I bought some brass blackener from a jewelry supply house a couple of years ago and had a terrible time with it. This, after chemically cleaning with a bone fide metal cleaning agent, the object to be blackened. The color, after dipping was beautiful but rubbed right off. A complaint to the seller straightened everything out. I was told that the best way to oxidize brass is to use a very weak solution so that the oxidizing solution works very slowly and penetrates thoroughly.

I tried it and it works great. BTW, It is a lot cheaper to buy the blackening solution from a jewelry supply house. As I recall a pint bottle cost under $12.00.
{Dana L. McCalip}

For those who have had problems blackening brass as I have in the past (i.e., the black flakes off immediately) the solution is quite simple. Using Dana McCalip's advice in an earlier message I was able to get perfect results with Brass Black. The simple answer lies in using a dilute solution...I had best results with a 1:10 dilution of Brass Black to water. In this case less is definitely more. Just follow these easy steps:

Keep your fingers (i.e. oil) off the brass after the initial acetone wash. Surgical gloves work well. I believe that the above steps will work with most blackeners provided they are allowed to etch and not just oxidize the metal.

Sorry to bother you pros again with this info but I believe it will be of use to those frustrated novices among us who are tired of the flaky-black-metal-syndrome.
{Greg Herbert, D.V.M.}

There cannot be too much emphasis placed on the proper preparation or cleansing of the metal prior to dipping in the oxidizing solution. One of the best cleaning procedures is a strong scrubbing with a solution of ammonia, soap and water. After cleansing, dry with a clean cloth and do not handle or touch with your bare hands. Handle only on the edges if you must or with tweezers or tongs, etc.

After the oxidation or surface coloring is complete be sure to neutralize the coating by rinsing thoroughly with cold water. An improperly rinsed item will continue oxidizing until the part is a crumbling mass of mineral salts. This happened to the chain rigging part of the topsail halyards on some of the models built in the late 1920's for Chicago's Museum of Science and Industry. All of the chain rigging had to be replaced.
{Dana McCalip}

On a related topic, polished brass (such as for model mounts) is best cleaned and then coated with ordinary shellac, with the brass about the temperature of boiling water -- this drives off the alcohol quickly, and gives a much harder finish. (And, you're less likely to get fingerprints on metal that hot!)
{John O. Kopf}
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