US1288657A - Method of preparing printing-plates. - Google Patents

Description

E. E. wovomvt METHOD OF PREPARING PRINTING PLATES.

' D DEC 13 191 1,288,657.. v Patented Dec.24,1918.

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EMIL E. NOVOTNY, RIVERSIDE, ILLINOIS, ASSIGNOR TO J. STOGDELL STOKES, OF MOORESTOWN, NEW JERSEY.

' underlay and overlay iIlCOlPOl'EItBCl in the plate;

METH OD 0F PREPARING PRINTING-PLATES:

To all whom it may concern Be it known that I, E1111. E. citizen of the United States, residing at Riverside, in the county of Cook and State of Illinois, have invented certain new and useful Improvements in Methods of Preparing Printing-Plates, of which the following is a specification.

This invention relates to an improved method of preparing printing plates having metallic printing surfaces, such as electrotypes, stereotypes, and etchings.

' As is known to those skilled in the printing art, the usual printing plate, prior to its use on the press, must undergo certain makeready treatment inorder to insure proper results in the printing operation. In preparing the plate, therefore, it is the common practice for the pressman to resort to the use of underlay and overlay, but such make-ready does not of itself form an integralpart of the plate, that is to say, is not As contradistinguished from this ordinary practice I propose to prepare the printing plate by such NOVOTNY, a

a method, that the necessary or desired make-ready will be lncorporated in the plateitself, thereby obviating the use of separate when the plate is in the press, as my improved plate when completed, will be ready for immediate use, without additional treatment.

Another advantage 1ncident to so incorporating the make-ready in the plate itself,

as is done with my invention, is that I am enabled to use, in the preparation of the plate, certain standard make-ready, applicable. to the particular press upon which a plate is to be used and this standard makeready may also be repeatedly employed for the preparation of as many plates as desired. Of course in printing make-ready is required, not only to compensate for errors such as those in the type body but also for errors. due to some peculiarity or defect of the particular press. It is therefore the practice for the pressman, on'practically every job, to prepare make-ready to compensate for this press defect. of so preparing the make-ready each time is apparent when it is to be considered that paper or other material of a compressible nature is used for the make-ready and con scquently will, during the running of the Specification of Letters Patent.

being no longer accurate. my lnvention I may use make-ready which only used to be taken.

The necessity.

Patented'Dec. 2d, 1918.

Application filed December 13, 1916. Serial No. 136,675.

press, be more or less affected by the pressure, so that finally it has In the practice of is standardized or permanently prepared for these press errors, and as such make-ready is temporarily in the preparation of the plate and is not usedupon the press itself, or during. the printing operation, it may be employed in the preparation of other plates.

In the accompanying drawings,

Figure 1 is a cross sectional view taken through a conventional form of casting box and showing a step in the production of the plate. 1 v

Fig. '2 is a cross sectional view taken through the plate and its backing after it has been removed from the casting box. I Fig. 3 is a similar view of the plate itself after the phenolic backing has been removed therefrom and after the back of'the plate has beenshaved to final dimension,

Fig. 4- is a cross sectional view through a curved plate.

In practising the invention the ordinary metallic plate, made in the usual manner from a previously set type body or etching and which plate-at this time is of greater thickness than will be finally desired or required, is placed in a rigid proof press which is so constructed as to accuracy, that it will not of itself impart any errors to the proof The proof taken on this press will, however, in all probability show certain usual impressional errors due to the irregularities of the plate, and these must be compensated for-of course by the usual make-ready, as must also certain errors which will be due to the peculiarities of the particular press upon which the plate is to be finally used. Furthermore, it may be desired to employ make-ready to insure such pressure as may be necessary toobtain a. particular kind of printing, such, for instance, as where it is desired to have one'part of the printing appear shaded or heavier than another portion.

The proof having, thus been taken, the usual corrections thereto are made and-the proper amount of make-ready is determined upon,and said make-ready which is in the to be replaced as.

. section 7 of the castin box condensite,

then re-inked and the proof-re-taken, and this practice is continued until the print or prints produced from the plate reveal the character of printing desired? The plate and the make-ready are now removed from the proof press and-such make-ready which formed overlay on the pressis secured to the back of the plate, preferably by pasting its edges thereto and coincident with the type matter to be corrected. The face of such plate is now cleaned,'and when dry, is coated with a weak solution of soap and water which acts as a separating medium. The plate which is shown at l, is now placed withthe make-ready so positioned, as illustrated at 2, in a casting box 8. This casting box, as conventionally illustrated in the drawings, includes a bottom or bed 4, upon which are mounted bearers 5, which are arranged to constitute a four sided or rectangular frame, suitable vents 6 being provided for the escape of surplus material, as hereinafter described. The top of the casting box is indicated at 7 stood that the casting box may be heated in any manner desired. The plate 1 with the make-ready 2' properly positioned and attached to the bottom thereof, as above mentioned, is placed on the bed'of this casting box with the printing or type surface of the plate uppermost, and upon this printing or type surface is placed the plastic material, preferably in the nature of a phenolic condensation product of which there are several well known kinds, such as or bakelite. This layer or sheet 8, if desired, is preferably heated prior to placing it upon the plate 2 so that it is in a suitable plastic or soft condition when imposed upon the printing surface of the plate. ressure is now applie by lowering the top until it rests upon the top faces of the bearers 5. to be noted that this phenolic product or 'material shown at 8 even in its plastic condition has but a restricted flow and is confined against undue diffusion or spreading by the frame formed by the bearers 5, and if the top 7 of the casting box be rapidly closed and pressed against the phenolic material 8, the surplus material will escape but slowl through the vents 6. the entire cubical area formed by the top and bottom and bearers of the casting box will be completely filled and the plastic or sluggish phenolic material being unable to escape acts as a flexible ram against the metallic printing plate 1 forcing this plate downward so that themake-ready 2 will be actually embedded in the bottom of the plate 1 andthe entire bottom surface of the plate will be brought against the bed of the casting box. Of course this forcing ofthe make-ready into the body of the plate 1 will result in the and will push terial thereon and it is to be undera layer or sheet 8 of.

Now it is havin prepared The result will be that g to a flat level.

corresponding or complementary amount of the material so that the make-ready compensation will appear on the printing face of the plate. The casting box may now be permitted to cool and is then opened and the plate with the layer or body ofphenolic mais removed from the casting box. The phenolic layer 8 at this time having assumed its set or hardened form may now be placed face downward ona suitable flat, rigid support such as the bed of a shaving machine, and as the bottom of the metallic printing plate 1 is now uppermost the .make-ready may be removed or stripped therefrom, leavin irregularities in the back of this plate 1. he bottom or non-printing face of the metallic plate 1 is now shaved to the desired degree or extent so as to resent an absolutely flat, smooth surface an When the phenolic layer is stripped from the printing face, the metallic printing plate itself, which is now of the proper thickness and ready for use on the ress will appear as shown in Fig. .3. It wil be noted in connection' with the material equivalent to the make-ready employed has been caused to appear on the front of the face with the required regulari.

ties and irregularities, this taking place as above mentioned during the treatment of the plate in the casting box. I might'herein mention that in-connection with the making of the plate I may employ what may be termed standard make-ready;- Words, a particular press may have certain plate shown in Fig.3 that.

in other 7 structural defects therein which may have tobe provided for in practically every instance; and in order to embody this in the plate If; would previously ascertain what make-ready would be necessary in this connection, and such make-ready would at the time of treating the plate in the casting box place such standard make-ready on the bed of the casting box or beneath the plate and employ it as a part of the complete make-ready to which the plate was subjected during its preparation. Then when the make-ready ,is-siibsequently stripped from the printing plate after the latter has been removed from the casting box this standard make-ready could be laid aside and preserved and then used in the preparation of subsequent plates. If it is desired to produce a curved printing plate such as is shown at 9 in Fig. 4, this form of plate being adapted for use in connection with the rotary press, I would proceed as above described for the making of the flat plate up to and including the operation of shaving the bottom of the'pla'te. However, instead of then immediately stripping the phenolic layer from the face of the flat plate, I would permit such layer to remain thereon and then subject both the metallic plate and its phenolic layer to the action of sufficient heat to make the phenolic layer flexible and would then subject the metallic plate with such flexible imposed backing layer to the action of a bending machine of any suitable typefor the purpose of curving or bending the metallic plate to the desired radius or curvature. Inasmuch as the metallic plate under such circumstances is solidly backed up by the layer of phenolic material I insure that uniformity of curvature throughout the entire area of the plate will be attained with practically no stretching of the printing plate because the bending or curving of the surface of the plate takes place in the neutral arc of the two bodies of material, or the plate andthe backing. Consequently, the printing face of the plate will not be distorted, The phenolic backing layer may now be stripped and the curved plate shown in Fig. 4 is the result.

WVhile I have herein shown and described a preferred manner of practising the invention, I wish it to be understood that I do not limit myself to all the details herein set forth by way of illustration, as modification and variation may be made without departingfrom the spirit of the invention or exceeding the scope of the appended claims.

What I claim is:

. 1. The herein described method of preparing a printing plate which comprises placing a predetermined amount of make-ready material against the back of the plate, imposing upon the face of the plate abody of plastic material and subjecting said plastic material and'pl'ate to pressure while in a confined space whereby the make-ready is.

embedded in the back ofthe plate, while material of the body of the plate complemen-.

plate and removing the plastic material from v the face thereof.

2. The herein described method of preparing a. printing plate which comprises placing a predetermined amount of make-ready material against the back of the plate, im-

posing upon the face of the plate a body of sluggish, flowing plastic material and subjecting said plastic material and plate to pressure while in a confined space whereby the plastic material acts as a ram the makeready is embedded in the back of the plate while the material of the body of the plate complementary to the make-ready employed is brought to the face of the plate, permitting said plastic material to set while under pressure, then removing the embedded makeready from the' back of the plate and then removing the plastic material from the face of such plate.

4. The herein described method of preparing a printing plate which comprises placing against the back of the plate a predetermined amount of make-ready material, in-

cluding make-ready material standardized to the errors of the press upon which the plate is to be used, imposing upon the face of the plate a body of plastic material and subjecting said plastic material and plate to pressure, and then removing the plastic ma terial and the make-ready from the plate.

5. The herein described method of preparing a metallic printing plate which comprises placing a predetermined amount of makeready material against one face of the plate, imposing upon the opposite face of the plate a body of plastic material, subjecting said plastic'materi'al and plate to pressure in a confied space, whereby the plaster acts as a ram certain of the material of the plate is forced by the make-ready to the opposite surface from the make-ready, and then re-.

moving the make-ready, then shaving the back of theplate and then removing the plastic material from the plate.

In testimony whereof I affix my signature.

EMIL E. 'NOVOTNY.

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