Hectography
As Hektografie or hectograph (from ancient Greek ἑκατόν Hecaton , German , one hundred ' and -graphy , literally "hundred letters" about "hundredfold increase") be the transfer printing refers to methods by which documents without the use of a press , but by means of a template-marking, the die , could be reproduced .
Basics
What all hectography processes have in common is that a special ink is handwritten or transferred from a colored sheet or ribbon - for example, by typewriter impact - onto a surface usually coated with a special gelatin mixture . From this, prints are then made on absorbent paper using various processes .
From the 19th century
Originally, the template was written on the right way round and printed on a bed of glue . The ink took over this as a negative. Then, when a sheet of paper is placed on the plate and moderate pressure is applied, a sufficient amount of dye is applied to the paper to produce a very clear copy. However, enough dye remains on the plate to be able to make a large number of copies one after the other and without further manipulation. Finally, the writing can be removed from the glue surface with a damp sponge and the glue mixture can be used again.
According to a patent specification from 1879 for Kwaisser and Husak, the glue mass was melted together from one part gelatine , four parts glycerine at 30 ° Bé and two parts water at moderate heat. An alternative method melts 100 grams of the finest gelatine with 400–500 cm³ of freshly precipitated and still moist sulfuric acid barite in a water bath, adds 100 grams of dextrin and - depending on the concentration - 1000–1200 grams of glycerine, lets it cool while stirring occasionally and pours it still flowing mass in a flat tin box, in which it solidifies.
The inks to be used consist of one part methyl aniline violet , seven parts distilled water and one part alcohol - or two parts rosaniline ( aniline red ), ten parts water and one part alcohol. The best ink is a highly concentrated aqueous solution of the purest methyl violet or a concentrated solution of eosin .
A special variant of this process was the hectograph roll , which was still used well into the second half of the 20th century, especially on board cargo ships , because many of the documents used there deviated from the standard paper formats and were therefore not suitable for other processes.
20th century
In the 20th century, after forerunners, some of which had been tested before the turn of the century, a process emerged that ended in the stencil printer. If the die is created the wrong way round - as a negative - it can be used directly as a print template. For this purpose, a special, two-layer stencil paper was used, in which a layer of color on the top of the second layer transferred the color to the back of the upper sheet at the places described with sufficient pressure. This laterally reversed matrix , which is manufactured in a similar way to offset printing and which is clamped on a crank-operated roller in most devices, can be moistened with a color-dissolving agent (for example alcohol / spirit) - albeit quite limited, namely actually limited to a few hundred - Make number of copies. In order to improve the transfer of ink to the die when writing on the typewriter, a hard film (made of plastic, for example) was usually placed between it and the roller.
Applications
In the office as well as in school and teaching, the process played a major role, as it was by far the cheapest way to make copies. The relatively inexpensive hectographs (also transfer printers or colloquially pasta machines ) allowed z. For example, pupils and students can also produce leaflets and school newspapers without having to use the services of a print shop (in 1970 simple, easily transportable devices cost around 130 DM ). In West Germany, hectographs were widespread in schools until the mid-1990s, when they were increasingly replaced by photocopiers , which have now become affordable for schools with low budgets .
In the late 19th and early 20th centuries, hectography was often the only way for people in the political resistance to distribute any significant number of printed matter. This procedure was used, for example, by resistance groups in the Third Reich . The Red Shock Troop, for example, printed its illegal newspaper and the White Rose its leaflets with hectographs such as the Greif Rapid.
Hectographs are, however, characterized by a decidedly inferior print image (in no way comparable to xerography or today's inkjet or laser printing ), which was also often not purely black, but purple like an ink pen and which became increasingly poorer as the number of copies increased . A special coated hectography paper was used to mitigate this effect . In addition, the usual hectographies fade easily. Graphics were only possible as line drawings due to the lack of a grid option . As a rule, the matrices could only be used once; Errors could only be corrected with a special correction varnish. In addition, fresh hectographs had a characteristic smell of the solvent attached.
Related processes and apparatus
Similar devices are the mimeograph invented by Edison , as well as autograph , chromograph , multigraph , kilograph , ormig ( GDR - synonym for hectography, also occurring in the West , after the West Berlin Ormig organizational means GmbH ), copying press, etc.
The Jacobsen collography represents a real advance compared to the copies made with highly perishable aniline inks . According to this process, you write on well-sized paper with a special kampa ink , transfer the writing to a dampened glue plate and blacken it with the help of a roller with letterpress ink. The latter only sticks to the areas of the glue board that are covered by the writing, if this was first sufficiently moistened. Here, too, the copy is obtained by simply laying on the paper and applying moderate pressure. For each new copy, the writing on the glue board has to be blackened anew, and so you can get up to 150 pure transfers, the last of which have the same blackness as the first, while the hectographic copies are ultimately weaker.
Zuccatos Trypograph is a kind of screen printing process. You write with a hard pen on specially prepared paper, which you place on a finely roughened iron board. By applying pressure, the paper has tiny holes in the areas deformed by the writing and is transformed into a stencil , so to speak . This is now fastened in a device with a printing frame, but the sheet of ordinary paper to be printed is pushed under it every time. A rubber squeegee soaked in some paint is then passed over the stencil, the paint penetrating through the holes and creating a copy of the writing on the paper. A single stencil is said to be able to deliver up to 7000 impressions, but promote production so quickly that 400 impressions can be made in an hour.
So-called risography devices work with a similar process but fully automated as a copier . The classic blueprint was created using the cyanotype .
Another method for producing the printing matrices uses a thermal copying process, for this purpose special matrix sets (ink sheet and matrix paper) are offered. This made it possible to produce any number of identical printing matrices from originals printed black on one side using a thermal copying process. For this purpose, the original, printed black on one side, was pulled through the thermal copier in contact. This consists of a driven glass roller that is heated from the inside by a halogen rod. Rubber rollers guide the original together with the matrix set over this roller, whereby the black writing heats up so much that the layer of ink on the ink sheet melts and the color is transferred to the matrix. However, the white areas of the original remain below the melting temperature of the color layer. The backing paper of these thermal copy matrices is much thinner, which affects both the print quality and the size of the print run. Such matrices are still used today by many tattoo studios to transfer drawings onto the skin.
Web links
Individual evidence
- ↑ Dennis Egginger-Gonzalez: The Red Assault Troop. An early left-wing socialist resistance group against National Socialism. Lukas Verlag, Berlin 2018, ISBN 978-3867322744 (book contains numerous facsimiles of the resistance newspaper of the same name).