Fume Bluing
Fume bluing is a variant of the previous method. All steps and all equipment remain the some except for the Rust Producing Step. In fume bluing, the rust is produced by fuming the gun parts in acid fumes. Boiling, Removal from Water, Carding and Repetition are followed exactly as above.
Materials.
Instead of the Classic American Rust Bluing Solution, the cotton fluff and the clothes pin you use the following:
1. Nitric Acid, Reagent Grade, 70% by weight.
2. Hydrochloric Acid, Reagent Grade, 37% by weight. Although these are common acids, and Reagent Grade the most common strength, an average pharmacy won't have them. Any high school chemistry lab class will. Any college or university chemistry lab will. In fact, these strengths are about all they will hove. Get o couple of ounces of each from one of these sources. The acids cost little. Use gloss bottles with plastic caps having a seal of polyethylene or polypropylene. Best for Nitric Acid is a bottle with a ground glass stopper, but they aren't too common any more. A chemistry lab might have one. CAU-TION: Do not allow acids to contact your skin or eyes, par-ticularly not your eyes. If contact occurs, flush the area with large amounts of water. If acid contacts the eyes, flush with water and call a doctor immediately. Do not swallow the acids. Nitric Acid is toxic. The antidote is to drink large quantities of water containing Milk of Mag-nesia or milk or soap and water. Then call a doctor. Do not breathe the vapors. In other words, use with adequate ventilation.
We would offer a Fume Bluing Kit containing the above acids. However, the impossibility of shipping the acids to .you prohibits this.
3. Several eyedroppers, purchased at a pharmacy.
4. Three or four glass or plastic dishes, 2" diameter, to hold drops of acids.
5. A fuming box to use to fume the gun parts. There are several possibilities.For small parts a plastic refrigerator storage box is good. There are a variety of sizes, com-monly found. For barrels, you need something larger. Minimum size is 4" x 4" x 36". The fastest way to obtain such a box (it must be either plastic or glass to resist the fumes) is to order one of the chemical tanks from either Frank Mittermeier or from page 142 of Catalog #34, Brow-nell's, Inc., Montezuma, Iowa 50171. The tank lacks a lid. Make a lid from a piece of utility grade, clear 1/8" acrylic sheet, from any plastics store. Place over the box and weight for a nearly air-tight seal. This way, you can watch the bluing action. Not as professional as this, but serv-iceable, inexpensive and made from readily obtainable materials is a long cardboard box, lined with a sheet of clear polyethylene, the type sold to cover windows in win-ter months. Tape any seams with plastic tape. For a clear top, use acrylic sheet or a piece of the polyethylene sheet, mounted on a frame.
6. Plugs to seal the ends of rifle and shotgun bores. These should be neoprene or polyethylene. However, common corks do well, even though made of natural material. Too much wood or cork present in the box preferentially absorbs all the fumes, stopping the bluing action.
Rust Producing Step with Fume Bluing.
Place the pro-perly polished and cleaned metal parts into the fuming box. Handle using gloves. Plastic holding fixtures, to hold the parts off the bottom of the box, would be appropriate. Make sure that the bores are plugged. Place the glass or plastic dishes in the bottom of the box, three in the long box and one in the small box. Using on eyedropper, add one or two drops of Reagent Grade Hydrochloric Acid to each dish. Then quickly add double that amount of Rea-gent Grade Nitric Acid to each dish. Use another dropper for this. Quickly cover the box. Wait three k then quickly remove the parts from the box, recoveriri the box quickly. Unplug the bores and go on with the bpi? ing and carding steps.
Please note that you must first determine the number of drops of acid to use. This depends upon the size of -- Your fuming box and the temperature and humidity of Your lo-cality. For best results fume bluing must be done at a temperature above 75°F. Gas phase reactions are very temperature sensitive. If done properly, after about twenty minutes in the box a layer of black "velvet" grows on the metal surface. At high humidities the color may be brown. With a new soft plastic box a short break-in period may be required. The plastic needs to become saturated with the fumes to work well. At the end of three hours the sur-face coating is uniform. Too little acid, and you see little reaction. Too much, and the coating grows to an extreme, attracts water vapor from the air, which condenses on the surface, making it very wet, and in some cases giving it a greenish color. EXperiment first with a small piece of scrap metal to determine the number of acid drops.
Finally, I suggest that you do not add additional drops of acid to the dishes during the repetition steps. If you act quickly in removing the parts from the box, these heavy gases leave the box very little. The little which escapes reduces the fume concentration. This improves the quality of the finished blue. Like the Classic American Rust Bluing Solution, the fumes cause the rust to form, but the fumes are also a blue remover. Lessening the fume concentration with each repetition helps to preserve the blue already on the surface, while adding to it.
CAUTION: Although the acid fumes are in low concen-tration in the box, such fumes are toxic. So use this process with due caution and in a well ventilated area. The resulting fume blue is finer grained than that produced by the Classic solution. It is both beautiful and durable.
