US2052266A - Reproducing crayon - Google Patents

Description

Patented Aug. 25, 1936 PATENT oFricE .REPRODUCING CRAYON Hans Wieneke, Thalfang, near Bemcastel,

Germany No Drawing. Application February 7, 1935, Serial No. 5,506. lln Germany October 19, 1933 2 Claims. (c1. rte- These pencils etc. contain substances which are capable of effecting the direct tanning of phototypic and other colloid layers usual in the graphic arts.' It drawings made with such pencils etc.

a: are squeegeed or pressedon to moistened colloid layers of the'said kind, thena faithful mirror image of the drawing ;is formedon the surface thereof which image has'the property either of directly tanning the colloid layer and so produc- 1c ing a tanned image on it, which can be used for the. production of phototypic prints and the like.

Sticks of marking composition ready for use which enable a very valuable printing surface to be so simply prepared have not heretofore 15 been known. Since the Very start of lithography the greasy lithographic compositions have remained the only marking sticks which are forth with ready for use which enable reproductions of drawings in fatty inks to be made either dim rectly or by transfer. The field of application is limited, however. Draughtsmen and artists prefer lead and charcoal sticks and the like to greasy compositions and only employ the latter when a printing image is to be rapidly prepared 25 on stone or zinc and the like. 1

The necessity of using special chalk grain paper and the like for the drawing made with greasy marking composition also makes the use of the lithographic pencil difficult.

30 Another disadvantage is that the original drawing is lost during transfer.

Many have regretted the existing impossibility of directly reproducing their hand drawings, and therefore they will welcome the possibility pro- 5 vided by the present invention of being able rapidly to reproduce hand drawings, prepared with pencils which as regards utility differ inno way from ordinary lead pencils, charcoal, chalk sticks and the like very simply and without ex- 40 tensive apparatus.

The use of tanning liquids in the form of chemical inks is known. With these, however,

into dichromate solutions. The sticks must always be kept sufficiently moist during the drawing but notmoist enough for liquid to drop off (of; Roth, Der Kiinstl'erhandriick). Liquid dichromate, however, which is applied to the 5..

dry gelatin layer with the charcoal is not in itself 'a tanning agent and it tends to penetrate into the colloidlayer (which it must first of all soften) andto spread in an undesirable manner. Furthermore, drawings satisfying high requiremen-ts cannot be prepared with very moist charcoal. There is the further difficulty of having to draw a mirror image of the design, etc. on the colloid layer itself. The tanning action takes place only on drying and gives rise to a coarsened print image. It is not surprising in View of these drawbacks that this process of marking with moist dichromate sticks has not attained practical importance.

The use of the new drawing pencils etc. on the other hand enables for the first time lead pencil, charcoal, chalk, etc. drawings to be made which, when applied under pressure directly on to the moist colloid layers which are usual in the graphic arts, produce on these an unsurpassed sharp tanned image, which, when using a photomechanical layer, represents a superior printing image on the same.

The method provided by the invention may for example be carried out as follows, gelatin layers being employed.

The drawing is prepared with a pencil or stick containing tanning substances. The drawing paper may be so chosen that it ensures a suitable action, rough paper for charcoal drawings, for example, and smoother or very smooth paper for graphite lead drawings according to the hardness of the lead. For the printing surface (colloid layer) if only a small number of copies is required (say up to 30) it is advisable to use reprint 40 or transfer paper, which is cheap. If a large number of copies is to be taken, e. g. up to several thousand, Agfa photomechanical film (Lichtdruckfilm) is recommended. The sheet, somewhat excessive in size, cut off from the roll is moistened in cold water for a few minutes and then freed from excess water. The moist sheet is now laid upon the drawing and rubbed on the back with a cloth. If now the sheet and drawing are separated a true image of the drawing will be found on the former which represents the printing image. It can be forthwith inked with greasy ink and used for printing copies. An intermediate drying (as is usual in the photomechanical and oil transfer process) is recommended, however. A press is not absolutely necessary since good imprints are obtainable by simply rubbing on and drawing off the printing paper.

Drawing pencils, etc., suitable for use in carrying out this process may be made for example as follows: Porous sticks of the pencil etc. material, e. g. so called charcoal crayon, are boiled in concentrated chrome alum solution in the presence of glycerol until the charcoal sticks are completely saturated; the sticks are then thoroughly dried and coated with varnish or lacquer. Instead of chrome alum, alum and other salts of aluminum can be used. Sticks of chalk and graphite lead pencils which are capable of tanning can be made in a similar way to charcoal sticks with employment of tanning metal salts. Tannin and other organic tanning substances are less suitable for the purpose.

The method in which the pencil or crayon herein described is used has a whole series of advantages over the methods heretofore known. The originals can be prepared by the usual procedure of the art, since the use of the directly or indirectly tanning drawing pencils etc. does not necessitate any change. The originals are retained, although in a somewhat weakened state. For making reproductions no special expensive photographing apparatus is necessary: exposing appliances and exposing defects are eliminated, as well as a lengthy preparation of the printing layer requiring apparatus. The resulting prints are of value and are to be regarded as facsimiles. On account of its simplicity the method is not 5 only convenient for use by technical workers but also by architects and artists.

In technical practice the printing off of large numbers of impressions is attained by transfer of the printing surface, coloured with developing 10 or transfer ink, on to offset zinc.

In the case of planographic printing with stone and zinc plates a printing off on to transfer paper must be interposed on account of drawing reversal.

In the phototypic printing art the finest stump tones and shadings are reproducible. If a phototypic wrinkle grain is desired, this can be produced in the known manner, for example by means of an acid-formalin bath.

What I claim is:

1. A marking composition for the production of reproducible drawings, writing, etc., comprising charcoal, an alum and glycerol.

2. A drawing material for the production of reproducible drawings, writing, etc., comprising charcoal, a minor quantity of glycerol and at least one substance capable of exerting a tanning eiTect.

HANS WIENEKE.