Carbon black

/ char • kole   blak /

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How Carbon black is made:

Origin: plant & artificial Burnt wood
Natural variety of pigment

The name carbon black is generally used as a generic name for those blacks that are made from the partial burning or carbonizing of oil, wood, vegetables and other organic matter. Best prepared from vine clippings, fruit pits, or small twigs, which are partially burned, and then ground. Most charcoal black contains various minerals and tarry plant hydrocarbons. Produces slow-drying paint.

Artificial variety of pigment In 1864, a process was developed in America for a black more suitable for watercolor. It was widely employed in 1884. The American process used natural gas as the raw material. The smoky flame resulting from the burning of natural gas was first directed to cool revolving metal drums. The black deposits were automatically removed from the sides of the drums with scrapers. The resultant powder was of a finer grain than other blacks allowing it to spread better in watercolor. It was a stable pigment, unaffected by light and air
19th century recipe This black results from the calcination of wine-lees and tartar, and is manufactured on a large scale in some districts of Germany, in the environs of Mentz, and even in France. This operation is performed in large cylindric vessels, or in pots, having an aperture in the cover to afford a passage to the smoke, and to the acid and alkaline vapors which escape during the process. When no more smoke is observed, the operation is finished. The remaining matter, which is merely a mixture of salts and a carbonaceous part very much attenuated, is then washed several times in boiling water, and it is reduced to the proper degree of fineness by grinding it on porphyry.
In the lab
  1. Twigs from nearly any type of tree, many woody shrubs, and woody vines may be used. Avoid twigs from growth less than one year old; they usually produce soft, powdery charcoal. Two-year-old growth is generally reliable. Dowel sticks and scrap lumber are also good sources of material. Nearly any kind of wood will make charcoal. (Important: Do not use treated lumber because of toxic fumes emitted during the roasting process.)
  2. Twigs may be of any diameter. Very thin twigs, however, will be too weak for drawing. Try twigs at least 1/4 to 3/8 inch (7 to 10 mm) in diameter. Lumber scraps may be ripped to one-fourth inch (7 mm) squares or larger. The wood will shrink as it turns into charcoal.
  3. Cut the twigs to the desired length (five to seven inches is good). Cut off forked joints, and peel away all the bark. If the twigs are cut from fresh, living tissue, they should be allowed to dry for a few days before going on to the next step.
  4. Wrap several dry sticks tightly in Extra Heavy aluminum foil so that no air may infiltrate the package. Air entering the package would reduce the sticks to ash rather than charcoal. If the aluminum comes in contact with open flame a hole could be burnt through the foil, spoiling the charcoal; so you might wrap a second layer of foil tightly around the package for security. (But don't overdo it; each layer of foil reduces the amount of heat reaching the wood.) Experiment first with five or six sticks per bundle. If the bundle contains more sticks, higher heat and longer roasting time will be required to completely carbonize the wood. Soft wood species, such as pine and cedar, will require less roasting time than hardwood species (such as birch, ash, oak, walnut).
  5. Place the package in the coals of a fireplace or a barbecue pit. It may take several hours (or overnight) in the coals for the sticks to carbonize and then cool down. Do not open the package until it has cooled enough to be handled comfortably. You must be willing to experiment beyond the first attempt. Too much heat will melt the foil. Insufficient heat will produce brands; you should get consistently good results after a few experiments. Charcoal can also be made in a ceramics kiln, which should be vented outdoors. If you use a ceramics kiln, experiment cautiously with temperatures above 300 degrees Celsius (572 degrees Fahrenheit). Hotter temperatures cause rapid carbonization and are hard to control.

The ground pigment:

Pile of ground Carbon black

Other blacks
(intro) - Bone black - Carbon black