A technical dictionary of printmaking, André Béguin.

INKING WITH A ROLLER. In the past the inking of relief blocks (woodcuts and typographic matter) was done with inking balls. Two such balls were first rubbed against each other to distribute the ink evenly. The next step was to touch or dab the block with the balls making sure that they were not rubbed into the intaglio areas. In 1790 the Englishman Nicholson invented the first roller (made of leather and stuffed with horse hair). Since then rollers have gone through several changes. They have been adapted to the various uses they were needed for and modified in order to avoid the defect of an overly dry roller surface. The first modification was an attempt to try to dampen the surface. Around 1819, J.N.Gannal invented a mixture of glue, molasses, and ammonia salts which gave a certain suppleness to the roller. At present leather rollers are used in lithographic work while rubber rollers are used for colour inking and woodcuts. Rollers made of gelatine are also used but usually for applying varnish. On printing presses the rollers are made of synthetic resins or a mixture of glue, gycerine, and sugar. Rollers must always be. properly maintained: the ink must be scraped off with a blade and only cleaned with turpentine oil. Leather rollers must remain smooth from use and should only be cleaned by rolling them on a flat surface covered with some turpentine oil until the excess ink stops coming off [rollers].
The film of ink deposited on a printing element must be thick enough to produce a precise impression but it must not be so thick as to run into intaglio areas below the reliefs since this would make the outlines imprecise and dirty the large white areas. The ink must be prepared on a flat, non-absorbant, surface such as a metal plate or a marble or glass slab. If a glass slab is used it should have a rough finish so that the ink will stick to it properly. A slightly grained lithographic stone can also serve the same purpose.
The inks must be mixed with oil and worked with a spatula until it reaches the right consistency. Then it may be spread over the printing surface with a roller. Make sure that the ink is evenly spread out. Excess ink can be removed from the roller by rolling it on another surface (this procedure is essential if one wishes fine lines to be printed).
The right consistency of the ink can only he judged by the printer himself. In all cases, however, the consistency must be such that the ink does not run into the intaglio areas. A well made ink should make a crackling noise when applied with a roller.
The wider a roller is the easier it will be to do the inking in one go, thus avoiding retouching. Also, the thicker the roller is, the easier it will be to ink the block with one revolution of the roller.
Before discovering the best inking procedure, a printer will have to do the job several times over on a trial and error basis. Each time the block must be printed the procedores must be begun afresh.

INKING WITH DABBERS. Generally speaking, dabbers are used to ink intaglio plates in which the lines must be stuffed with ink. Dabbers are used for inking fine engravings, etchings, and plates worked in various manners (crayon, etc.). Dabbers can also be used for dry points and aquatint work but in this case the inking must be done very cautiously. Inking with dabbers is quite brutal and because of this there is always the danger of damaging the grain of aquatint plates and closing the lines or crushing the burr of dry point plates. The best tool for inking dry point and aquatint plates is made with muslin but if dabbers must be used choose very soft dabbers stuffed with rags.
Begin the inking procedure by preparing the ink on a slab as described above but using inks made for intaglio plate printing. The surface of the slab need not be as big as for inking with rollers. When the ink is ready for use pile it up in one corner of the slab (in the past the ink was put in a kind of ink well or wooden box missing its top and one side). The next step is to pick up the necessary amount of ink with the dabber and transrer it to the plate. The plate must be kept warm while being inked (place it on a hot plate) so that it will be easier to make the ink penetrate the intaglio areas.
However, the plate must not be too warm as otherwise the ink will become too fluid and will nut resist the necessary wiping procedure which must be carried out after inking a plate. When a plate is inked for the first time one must make the ink penetrate the lines thoroughly by tapping the dabber on the plate.
The stuffing of lines must he quite vigorous so that the dabber will not fill a line superucially leaving an empty space below which would result in white area on the impression (this printing error is called blind printing ). The inks applied with dabbers are thick and heavy ones which, if necessary, can be diluted with a bit of oil. Greater fluidity can also be achieved by warming the plate to 35°C. (95°F.).
This latter step is especially helpful when the lines to be stuffed are very deep ones.
When the inking has been completed remove the plate from the source of heat and let the ink cool down before proceeding to wipe. The plate temperature can, however, be kept at around 20° to 25°C (68 to 77°F).

INKING WITH MUSLIN . As was mentioned above, this type of inking is used on delicate plates which may suffer from the tapping and stuffing done with a dabber. This type of inking is not very different from the dabber inking. The preparation of the ink is much the same as the ink used with dabbers but the inking itself is done very gently with tarlatan dabbers. The dabbers should be rubbed towards the corners of the plate so that the plate will not rip the cloth. Ripping should be avoided since it could cause the ink to become loaded with extraneous particles. The inking must be done so that the ink both penetrates properly and is evenly distributed. This is particularly important in the case of granulated plate surfaces which must be filled but not clogged with ink. The inking of dry point lines is also very very delicate and requires the close collaboration of the engraver and printer. In fact, if the inks is piled up on one side of the burr rather than on the other the final result will look quite different. If the dry point engraver does not print his own work he will have to give specific instructions to the printer as to what results he wants.
The wiping of intaglio plates should be done when the plate is quite cold. The reason for this is that there is very little ink caught in the granulated surface of the plate and thus it is easily pulled out by the wiping.

INKING WITH A DOLLY . This type of inking is done when several colours are used on the same plate. The printer wraps some muslin around his finger (making the finger look like a doll ). Usually very light hues are used which are then deposited in well defined areas of the plate. The printer must do this work with much judgement and taste because dolly inking is, in effect, the painting of an engraving and can be compared to the colouring of printed engravings [colour]. At times the little and very soft muslin dabbers which are used somewhat like brushes are also called dollies.

INKING WITH A BRUSH. This kind of inking is very similar to dolly inking. The brushes are dipped into the ink and are then used like a dolly. More delicate work can be done with brushes than with dollies. Brushes are also used to ink the details on fine engravings.
Larger brushes are used with watery inks to ink japanese woodcuts. This inking technique can be applied to either black and white or colour prints. In this case the ink is put in bowls. The brush is then dipped into the ink and brushed over the relief areas of the woodcut. The block is then covered with a sheet of paper in order to print the impression. In this process colours are printed individually one after the other [wood].
The inking techniques used in serigraphy are dealt with in the article devoted to this process.