US1978791A - Chromium plating of type - Google Patents

Description

Patented Oct. 30, 1934 CHBOMIUM PLATING OF TYPE Philip 1'. Hale, Toledo, Ohio No Drawing. Application November 21, 1932, Serial No. 643,797

13 Claims.

The main objects of this invention are: First to provide a method for the direct electrodeposition of chromium on type metal.

Second, to provide type and/or type plates having an exceptionally long life and improved printing characteristics.

Third, to provide a method of satisfactorily electroplating an alloy containing a predominant amount of lead with chromium.

Fourth, to provide a method of and means for rejuvenating worn type and type plates, whereby they are given a new substantially permanent printing face having improved printing properties.

Objects relating to details and economies of my invention will appear from the description to follow. The invention is defined and pointed out in the claims.

Type and type plates are made of an alloy which is generally designated as type metal. Type metal consists essentially of lead as a base metal, which is alloyed w.th varying amounts of tin and antimony generally, although in some cases, various other metals, such as zinc, copper and iron, are added to the composition of the alloy. The following is an old recipe for type metal: 61.3 lb. leads, 20.7 lb. tin, and 18.5 lb. antimony.

For good wear and good printing results, the face of the type should be hard and of good depth or clear cut. In use, the type face becomes shallow and finally must be discarded and recast. The same is true of type plates of type metal and of copper backed by type metal. The processing of a copper electrotype printing plate requires approximately 14 hours for the electrodeposition of the copper. Electrotype plates plated with copper are subject to rapid deterioration in use, due to the relatively soft copper face and the type metal back .ng commonly used. Conventional type and type plates of type metal also wear high points of metal, which is highly desirable,

away quickly.

Chromium is very hard, wears well and is not subject to corrosion. Its use as a face for type and type plates greatly prolongs their life and improves the character of the printing. However, the chromium plating of type metals has never before been successfully accomplished, because of difiiculty in making the chromium plating adhere to the type metal. Attempts have been made in the past to accomplish this by the use of interposed coatings of metals such as copper and/or nickel, but such processes areexpensive.

I have discovered a process of electrodepositing chromium directly on typ metal without the 55 aid of interposed coatings of metals, such as 0 per and/or nickel. The chromium printing face thereon increases the life of the type and printing plates from three to fifteen times and also results in improved work. According to my method, the time required for the chromium electroplating op- 00 eration is approximately only one hour. This results in a time saving of 13 hours over the prior copper electroplating process. The life of a chromium plated printing plate is a minimum of three times that of a combination; copper and type metal printing plate and ten to fifteen times that of type metal alone. It is thus seen that the chromium plated plates last-longer and cost less to manufacture than combination copper and type metal plates.

My method contemplates the use of any standard chromic acid plating bath. If the printing plate has been used, the ink is removed from the plate by the use of an ink remover such as benzine. The plate is then dry polished with whiting, or some other soft slightly abrasive powder, using a. soft cloth or brush, or by a mechanical method such as blasting, which leaves a positively dry polished surface. The plate is thereupon immediately immersed in the electroplating bath and allowed to remain until it reaches the temperature of the bath, approximately 140 F. The plate is then connected in electrical circuit with a current source and the anode. The voltage is preferably substantially 3.8 volts with the anode spaced approximately one inch from the cathode, although it is possible to use as low as 3.5 volts and as high as 4.2 volts for satisfactory results. These conditions may be simulated by varying the voltage and the anode spacing. The electrodeposition is allowed to continue for about one hour, at the end of which time the plate is provided with a clear and deep chromium face which is bright, hard, tough and durable.

The chromium tends to concentrate on the but sufficient chromium is deposited in the depressed portions so that the type does not have a tendency to take up and become compacted with ink. The life of the plate is renewed and prolonged and the character of the printing is greatly improved.

In preparing the plate for the bath, I prefer to use a dry polish, inasmuch as as it is safe, produces a high percentage of good work and provides a good adherency. However, as a substitute, the plate is dipped in a solution of acid or alkali which will not excessively etch or oxidize the type metal.-

1; have described my improvements in an em- 110 bodiment which I have found very practical. I have not attempted to describe other embodiments or adaptations, as it is believed this disclosure will enable thoseskilled in the art to. embody or adapt my improvements as may be desired. 7

Having thus described my invention, what I claim as new and desire to secure by Letters Patent is:

1. The process of electrodepositing chromium directly, on a cathode consisting of type metal platewith a standard chromic acid bath, which comprises cleaning ink from the plate with benzine or the like, dry polishing the printing face with whiting or other soft slightly abrasive powder using a soft cloth or brush which leaves a positively dry polished surface, immersing the plate in the bath and allowing it to reach the temperature thereof, and connecting the plate in circuit with a current source and the anode, the voltage being 3.3 volts with an anode spacing of one inch or under similar conditions of varying voltage and anode spacing, the voltage being proportional to the anode spacing.

2. The process of electrodepositing chromium directly on a cathode consisting of type metal plate with a chromic acid bath, which comprises cleaning the plate, dry polishing the printing face with soft slightly abrasive powder using a soft cloth which leaves a dry polished surface, immersing the plate in the bath and allowing it to reach the temperature thereof, and connecting the plate in circuit with a current source and the anode, the voltage being between 3.5 and 4.2 volts with an anode spacing of one inch.

3. The process of electrodepositing chromium directly on a cathode of type metal with a standard chromic acid bath, which comprises polishing the face of the type metal cathode until dry and clean, immersing the cathode in the bath and allowing it to reach the temperature thereof, and connecting the cathode to a current source and the anode, the ratio of voltage to anode spacing being substantially 3.8 volts to one inch of anode spacing.

4. The process of electrodepositing chromium directly on a cathode of type metal with a chromic acid bath, which comprises polishing the face of the type metal cathode until dry and clean, immersing the cathode in the bath and allowing it to reach the temperature thereof,

and connecting the cathode to a current source and the anode, the anode-cathode spacing being between 3.5 and 4.2 volts per inch.

5. The process of electrodepositing chromium directly on a cathode consisting of an alloy containing a predominant amount of lead with a standard chromic acid bath, which comprises dry' polishing the surface of the cathode to be plated, immersing the cathode in the bath, and passing a current from the anode to the cathode, the ratio of voltage to anode spacing being substantially 3.8 volts to one inch.

6. The process of electrodepositing chromium directly on a cathode consisting of an alloy containing a predominant amount of lead with a chromic acid bath, which comprises dry polishing the surface of the cathode to be plated, immersing the cathode in the bath, and passing a current from the anode to the cathode, the anodecathode spacing being between 3.5 and 4.2 volts per inch.

7. The process of rejuvenating the face of used type, which comprises cleaning and dry polishing said face, immersing the type face in a standard chromic acid electrolyte, allowing the type to reach the temperature of the bath, and connecting said type to a source of current and anode, whereby chromium is electrodeposited on said face, the voltage of the current in volts being 3.8 with an anode spacing of one inch.

8. The process of rejuvenating the face of used type, which comprises cleaning and dry polishing said face, immersing the type face in a chromic acid electrolyte, allowing the type to reach the temperature of the bath, and connecting said type to a source of current and anode, whereby chromium is electrodeposited on said face, the

anode-cathode spacing being between 3.5 and 4.2 volts per inch.

9. Themethod of electrodepositing chromium directly on a cathode consisting of a printing plate of type metal with a chromic acid bath, which comprises cleaning and drying the face of said plate, immersing it in the bath, and when the bath and plate have reached the same temperature connecting said plate in electric circuit relation with the anode and a current source for substantially one hour, the ratio of voltage in volts to anode spacing in inches being substantially 3.8 to 1.

10. The method of electrodepositing chromium directly on a cathode consisting of a printing plate of type metal with a chromic acid bath, which comprises cleaning and drying the face of said plate, immersing it in the bath, and when the bath and plate have reached the same temperature connecting said plate in electric circuit relation with the anode and a current source, the ratio of voltage in volts to anode spacing in inches being substantially 3.8 to 1.

11. The method of electrodepositing chromium directly on a cathode consisting of a printing plate of type metal with a chromic acid bath, which comprises cleaning and drying the face of said plate, immersing it in the bath, and connecting said plate in electric circuit relation with the anode and a current source, the ratio of voltage in volts to anode spacing in inches being substantially 3.8 to 1.

12. The process of chromium plating type metal, which comprises cleaning and drying the type metal, maintaining the type metal dry, immersing the dry type metal in a bath of chromic acid, spacing an anode approximately one inch from said type metal, and passing a current through the bath at a potential of between 3.5 and 4.2 volts.

13. In the art of electroplating type metal and the like directly with chromium in a bath of chromic acid, the steps which comprise thoroughly'drying the cathode, and immersing it in the oath'while dry, the anode being spaced substantially one inch from the cathode in the bath for a current at a potential of between 3.5 and 4.2