US1434989A - Blackboard - Google Patents

Description

G. W. BROOKS.

BLACKBOARD.

APPLICATION FILED MAY 2,1921.

Patented Nov. 7 1922.

6 w g T w b a w n e m 0 E a n m m m a 6, m a P m M h m WHM ww wf v m meab Base jwuuako'c (fieorye w. Erna/w (1H0: nun,

Patented Nov. 7, 1922.

enonen w. Bnooxs, or rornxa, KANSAS.

' BLACKBOARD.

Application filed May 2, 1921. Serial No. 465,953.

T 0 all whom it may concern:

Be it known that I, GEORGE W. BROOKS,

a citizen of the United States, residing at Topeka, in the county of Shawnee and State of Kansas, have invented certain new and useful Improvements in Blackboards, of which the following is a specification.

This invention relates to certain new and useful improvements in blackboards of that class formed of a metallic base or foundation with a writing surface applied thereto. I am aware thatit has been proposed to provide a flexible metallic blackboard having a writing surface appliedthereto; In oneform of such prior construction the blackboard is composed of a foundationv of very thin and flexible sheet steel, thefface of which is covered with a heavier material of elastic pigment to overcome the unevenness of the ordinary commercial steel as manufactured. v l On account of this steel being very uneven and full of buckles and varying angles it seems the patentee (Costello, Jan. 23, 1906) levels. up the surface with the elastic pigment, correcting the unevennessof the surface ofthe steel by the application of a layer of elastic pigment, and this foundation forms the blackboard. I

At the time when said patent was granted1906a commercial grade of steel, having a scaly and uneven surface, madeby the Bessemer process and rolled into sheets with the 'fiake of scale rolled in, made a very poor quality of sheet steel. This wasowmg to the poor state. of the development of rolling and it was practically impossible at that time to obtain a fiat 0r unwavy sheet. The application of a layer of elastic pigment was to overcome this objection and prepare a surface on the uneven foundations of the sheet steel for blackboard purposes. Great stress was given to the fact that the material used to cover this irregular surface should be properly covered with elastic and strong combination of materials and the patentee describes those suitably adapted to give the proper qualities to spread readily and smoothly to overcome the unevenness or faulty surface of the steel sheet.

Today, there has been perfected a practical level and true steel by a process known as pickling and patent leveling. By using a sheet of metal of this description prepared ,sioned by expansion joints, as

in this manner, I have reversed this idea and patent and depend upon the patent levellng surface of the sheet itself to form the true surface of the blackboard.

The coating of abrasive material which 1 apply does not cover up or smooth out any unevenness or irregularity in the sheet and only a light coating is necessary. It is a fact that I correct the faulty foundation by using patented leveled steel.

I make no claim to a flexible metal foundation, my blackboard being rigid and nonflexible, permanently set, and that is obtained by using suitable heavier gauge material which is non-flexible and not necessarily coated by flexible material and not one that can be rolled and, on account of its flexibility, shipped in a rolled form. My blackboard is non-flexible.

By my construction no trouble is occaa perfectly level sheet can be had by butt-welding toge'ther a plurality of contiguous sections,

and a continuous and level surface of differentsections cangbe obtained without the use of elongated holes or a cover plate for concealing the joints of the different sections of blackboard. V

.1 form a blackboard of a non-flexible metal base or foundation made by'the patented level process, which, ofcourse, is level and true does not have irregularities or waves and is coated with a suitable abrasive surface. It does not require a backing of any other material, but can be coated orgalvani'zed or sherardized or any other method may be used, primarily to protect it from lrusting,and the true and plain permanent surface may 'be used for blackboard purposes by suitably coating or covering the working surface.

It can be bent permanently into suitable shape and stiffened by application of angles and reinforcements to make a solid substantial blackboard of light weight material.

It can be made to conform to right angles or irregular corners of the building.

It can be made straight, cylindrical or irregular in shape and used as a portable board.

It is not subject to warping and the sun or heat does not crack or destroy it.

This metallic blackboard is coated with a base coat of enamel or analogous preparation to protect the metal against rusting. On the top of this coat are one or more coats of black or any other color enamel. These coats are baked on the metal and make a permanent finish.

The last or finished coatis formed of suitable proportions of emery flour. This makes a permanent covering which when baked on the metal gives the requisite amount of abrasive surface to cut into the chalk and leave the chalk trace on the board forming the letters intended to be made.

This preparation makes a permanent coat and different from slate in several respects.

By the process of enameling, an absolutely dark surface is obtained; either with a gloss or dull surface it makes a greater contrast with chalk than the slate color does.

By enameling the surface of metal it has a solid base and is not porous and the chalk does not grind away as quickly when the emery flour mixture is suitably proporcloned to the finished coat as it only uses enough chalk at each application to leave a trace of chalk.

Chalk hasto be cleaned out of a porous surface, but is erased from a metal board having an enamel surface very easily and leaves the board absolutely clean and free from chalk,

Other objects and advantages of the invention will hereinafter appear and the novel features thereof will be particularly pointed out in the appended claims.

The accompanying drawing illustrates an example of my present invention and in which is shown a perspective view of a portion of a blackboard constructed in accord ance with the principles of my invention as hereinbefore outlined, parts being removed and other part-s shown in section.

In the drawing,

1 designates the base or foundation of the boardwhich is of non-fiexible metal, preferably that made by the patented level process which is level and true without irregularities or waves, and 2 is an antirust preparation constituting the base coating, which may be ofenamel or analogous preparation to protect the metal plate against rusting.

3 designates a coating of black or any other color of enamel, of which there may be one, two or more coats one after each baking. The metallic base thus coated is baked so as tomake a permanent finish while the finishing coat 4, of an abrasive nature, such as a suitable mixture of emery flour, when baked on the coated metal, provides a permanent covering and gives the requisite amount of abrasive surface to cut into the chalk and leave the clear plain chalk trace on the board forming the characters intended to be made.

The emerycoating may be formed by mixing the requisite pro-portion of the emery with the coating of enamel.

What is claimed as new is 1. A blackboard or the like composed of a sheet steel inflexible base; and a plurality of coats of enamel thereon each independently baked, the last coating being of'an abrasive nature andthe whole constituting a hard, permanent level writing surface.

2. A blackboard formed of an inflexible metallic base, an antirrust coating thereon, a coating of enamel on said anti-rust coating, and a finishing coating embodying an abrasive substance, the same forming a hard permanent inflexible writing surface.

3. A blackboard formed of an inflexible metallic base, an anti-rust coating thereon, a coating of enamel on said anti-rust coating, and a finishing coating embodying an abrasive substance all baked to give a permanent finish, the same forming a hard permanent inflexible writing surface.

4. A blackboard .or the like composed of a sheet steel inflexible base; an anti-rust enamel coating'baked thereon, and a plurality of coats of enamel thereon each inclependently baked, the last coating being of an abrasive nature and the whole constituting a hard, permanent level inflexible writing surface.

In testimony whereof I aflix my signature.

GEORGE W. BROOKS.

Images