US325636A - George sutherland - Google Patents

Description

NITED STATES PATENT rrica.

GEORGE SUTHERLAND, OF ADELAIDE, SOUTH AUSTRALIA.

SPECIFICATICN forming part of Letters Patent NO. 325,636, dated Application filed January 2, 1885.

T0 aZZ whom it may concern:

Be it known that I, Gnonen SUTHERLAND, a subject of the Queen of Great Britain, residing in Adelaide, South Australia, have invented certain new and useful Improvements in Producing from Photographic Negatives Blocks or Plates Suitable for Typographic Surihce-Irinting, (for which I have obtained a patent in Great Britain, No. 9,026, dated June 16,1.S84,)of which the following is a specification.

The object of my invention is attaching by any adhesive substance a film or sheet of any material which has been impressed with the form of an engraved surface, capable of printing in a typographic press a series of marks producing the effect of an even tint or shade, to a relief produced by photographic means, and the rubbing or pressing the surface thus produecdwith some straight or plane surface, with the effect of increasing the size of the marks on the raised portions of the relief, and consequently rendering them capable ofprinting a series of marks having the effect of a darker shade or tint than the rest, the surface produced being thus capable of printing in a typographic press a series of marks large in the darker portions of the picture which it is intended to reproduce and smaller in the lighter portions.

For the purpose of my invention I prepare a photographic relief in the following manner: Having allowed one ounce of gelatine to swell in sufficient water to cover it, I add one-quarter of an ounce of sugar and dissolve the whole at a gentle heat, and then pour on boilingwater sufficient to double the quantity ofliquid, after which I sensitize the solution by adding from twenty to thirty drops of a saturated solution of bichromate of potash. On a plate of glass of suitable size I pour a sufficient quantity of this solution to float easily to the edges, and set the plate in a drafty situation, sheltcred from the daylight, until the gelatine is dry. I then expose the plate thus prepared to the rays of the sun under a negative of the portrait or picture which is to be reproduced, the exposure hour. I then place the plate in cold water and leave it to swell until the lightest portions of the picture have swelled to the height of about one-tenth of an inch. In order to lasting about a quarter of an September 1, 1885.

(No specimens.) Patented in England June 16, 1884. No. 9,026.

take a cast from the gelatine relief thus obtained, I rub the surface 'of the gelatine first with powdered alum, and then with a lather of soap, wipe it clean, and pour on plaster-ofparis, which, when set, is easily removed. In the cast thus formed the dark portions of the picture to be reproduced are represented by elevations and the light port-ions by depressions. I then rub the surface of the cast first with asmall quantity of common gum solution, andthen with gold-size made of linseed-oil boiled to a sticky consistency. The relief is then ready to receive the film impressed with the form of an engraved surface. This film is prepared as follows: I take a sheet of tin-foil, or any other material which will readily take the form of any surface on which it is pressed,

and place it on the surface of an engraved block of wood, metal, or any other suit-able material. The engraved block has raised lines, dots, or other marks arranged regularly so as to produce when printed from in anordinary typographic surl'ace-printin g press the effect of an even shade or tint. The tin-foil or other material, having been placed on the surface of the block, is covered with a piece of woolen cloth and submitted to pressure until an exact impression of the engraved surface has been communicated to it. I then remove it from the block and place it on the prepared surface of the plaster cast, the dots, lines, or other marks being uppermost. A piece of soft woolen or flannel cloth having been again placed above the tin-foil or other material, I submit the whole to a gentle pressure until it has taken the form of the surface of the plaster cast, yet without having the dots, lines, or other marks obliterated. The surface then presents the appearance of a series of raised eminences, of which the highest are situated on the raised portions of the plaster castthat is to say, on the portions of the picture which are darkest-the middle tints being partially raised, and the lightest'portions lying in the depressions. I then gently rub the surface with any instrument having a smooth even surface-such as the handle of an ordinaryleadpencil laid flat and passed backward and forward, or a slab of glass, metal, or other mate rial pressed gently on the raised dots or lines or other marks. The effect is that these portions of the surface of the tin-foil or other material which have the highest eminences receive the greatest pressure, and consequently the raised marks in these portions are most flattened out, the intermediate elevations having the raised marks flattened in proportion to their height. The pressure and rubbing are continued until on those portions of the surface which are intended to be 'capable'in the finished block or plate of printing pure black or the darkest shade the dots become merged into one another.

The surface thus produced is capable of being printed from, but is not strong enough to yield many impressions. I therefore take from it a cast, either plasterof-paris or in WZIXOI other suitable material, and make either a stereotype or an electrotype in the ordinary manner.

If the type-metal or copper or other surface so produced does not print a sufficiently dark picture, either in whole or in part, I rub the surface with a fiat piece of wood to which a piece of emery-cloth has been attached, or with any other flat or straight instrumentsuitablc forgrinding, filing, or pressing metals.

I claim as my invention The method of producing from photographic negatives blocks or plates for typographic surface-printing, which consists in attaching to aphotographic relief a film or sheet of any material which has been impressed with the form of an engraved surface capable of printing in a typographic press a series of marks producing the effect of an even tint or shade, and then rubbing or pressing the surface so produced with a smooth-faced instrument, whereby the size or breadth of the marks on the elevated portions of the relief are increased so as to render them capable of printing a series of marks having the effect of a darker shade or tint than the rest, the surface so produced being thus adapted to print a series of marks large in the darker portions of the picture to be reproduced and smaller in the lighter portions thereof, substantially as described.

In witness whereof I have hereunto signed my name in the presence of two subscribing witnesses.

GEORGE SUTHERLAND.

WVitnesses:

JOHN HARVEY FENLAYSON, Stanley Street, North Adelaide, South Australia.

ROBERT THOMSON,

Parlrside', South Australia.