US572004A - Blackboard - Google Patents

Description

(No Model.)

0. E. GREGORY.

BLAGKBOARD.

No. 572,004. Patented Nov. 24, 1896.

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UNITED STATES PATENT OFFICE.

CHARLES EZRA GREGORY, OF NASHVILLE, TENNESSEE.

BLACKBOARD.

SPECIFICATION forming part of Letters Patent No. 572,004, dated November 24, 1896. Application filed April 29, 1896. Serial No. 589,540. (No model.)

T 0 all whom it may concern.-

Be it known that 1, CHARLES EZRA GREG- ORY, a citizen of the United States, residing at Nashville, in the county of Davidson and State of Tennessee, have invented certain new and useful Improvements in Blackboards; and I do hereby declare the following to be a full, clear, and exact description of the invention, such as will enable others skilled in the art to which it appertains. to make and use the same. 1

The object of my said invention is to provide a blackboard with a surface adapted for practical and successful use with crayons of natural talc. Many attempts have heretofore been made to produce such a board, but with only partial success, of varying degrees, as a result. To produce such a board, I have first provided a composition for surfacing the material of which its base or body is composed, which when properly applied will produce the required surface, and, secondly,have devised the practically successful method of applying the same. These steps or elements, which together constitute my said invention and result in the character of blackboard desired, will first be fully described, and then summed up in the claims.

The. accompanying drawing illustrates a section of blackboard of my improved construction. It is composed of a cloth or fabric back a, faced with paper I), on which my improved surface a is mounted, as will be hereinafter more fully described, no special description of the board being necessary, except what will be incidental to the description of the method employed in producing the same.

The composition for surfacing or enameling the board is composed of the following ingredients in substantially the proportions stated: grain or wood alcohol, one gallon; gum-shellac, three pounds; black oXid manganese, three and three-fourths pounds; ultramarine-blue, six ounces; lampblack, eight ounces; isinglass, two ounces; saturated solution of guiac, eight ounces; Venice turpentine, eight ounces; fiour of talc, eight ounces. The leading element of said composition is black oxid of manganese, together with guiac and isinglass combined with the shellac, and it is the combination of these elements which mixture to the shellac solution.

one quart'of alcohol with one quart of water .half hour or until it is dissolved.

- I regard as of the most importance in the accomplishment of the desired end. Said composition is prepared as follows: First, dissolve the shellac in the alcohol and strain through a fine piece of muslin or cheese-cloth. Sift the black oxid of manganese through silk bolting-cloth, about No. 15, and use only that which passes through said cloth. Mix said manganese, the flour of talc, the lampblack, and the ultramarine-blue together. Add this Then dilute and in this place the two ounces of isinglass and place over a gentle heat and stir for a While warm strain through a piece of fine muslin or cheese-cloth. Then add this mixture to the first mixture by pouring in slowly and stirring all the time upon the principle of trituration. Then add the guiac and Venice turpentine. Thoroughly mix the whole and then allow it to stand for twelve or more hours, when it is complete and ready for use.

The board is made as follows: First, take good quality of strong fabric, such as sheeting, of the desiredsize, torn from the piece to insure that the edges run with the grain. Submerge the same in water and then wring out and spread on a smooth table prepared to receive it. Stretch it asmuch as possible in each direction and secure by tacking, placing the tacks about three inches apart. Then take a piece of good all jute or Manila paper of corresponding size and secure to the fabric. This is done preferably by good flourpaste, in which is placed a quantity of good quality Venice turpentine, the paper being first thoroughly coated with the paste, the

cloth then coated or sized with the same and 'stir and shake the mixture thoroughly until Pour a small.

all sediment is in suspense.

quantity (a pint is sufficient ordinarily) into a shallow vessel and apply with a chiselpointed brush (a four-inch brush will be found suitable) crosswise of the paper, coating the entire surface in a crosswise direction. Allow this coat to thoroughly dry,which usually requires about one hour. Rub the surface thus formed gently with No. 1 emerypaper and then apply another coat of the mixture in the reverse direction,the operation being repeated in the same manner until the required number of coats have been applied to produce the surface desired. In practice I have found that five coats make a most desirable surface for the purpose, and this is the number I usually employ. After the last coat has been applied it should be allowed to dry and harden for several hours, (six are usually sufficient,) and then the entire surface should be rubbed with a block of natural tale to render it smooth. Then the talc-flour is brushed off and the surface again rubbed with felt or cloth until the surface is perfectly clean and black, when the board material is finished and ready for use. It is taken from the table by cutting just inside the tacks, and may be made in panels of any size desired.

The board may be mounted in any suitable manner desired, either directly on the wall or on a frame. I mount them in three ways by cementing or pasting to the wall; by what is termed the shrinking process,which consists in sponging the back with water and allowing it to soak for ten to fifteen minutes, and then nailing to the wall or frame in the same manner as before described for securing to the table; It is then allowed to dry and shrink, and in twenty-four to forty-eight hours it will draw perfectly taut and be ready for use; and I also mount them on veneering, either two or three ply, in the following manner: First, cover the face side of the veneering with any kind of soft heavy paper securely attached by means of cement or paste. Then take a piece of the board to be mounted, of corresponding size, and secure it to the soft paper that has been secured to the veneering. This is done by thoroughly coating the cloth or back of the board with cement or paste and then coating or sizing the paper that has been secured to the veneering. Then apply the prepared board and roll with rollers in same manner as described in uniting the jute or Manila paper to the cloth, and in twenty-four hours it is ready for use. The object of placing the paper between the board and the veneering is to render the board, when completed, non-resonant.

The blackboard thus made has been found after extensive experiment to be a perfect blackboard for the purpose first stated. Natural talc crayons write upon it easily and smoothly, making a clear mark without, even after long use, in any manner injuring or scratching or cutting the surface. The marks are very easily removed by simply wiping with a dry piece of cloth or, preferably, a felt eraser. No water is required for cleaning it, as the felt eraser cleans the surface perfectly and leaves it clean and black.

I do not claim a board made up of the fabric and paper with an enamel surface, as I am aware that boards have long been so made. I am also aware that some of the elements of my composition have long been used in compositions for such surfaces; but I am not aware that black oXid of manganese in any combination or with guiac, flour of talc, and isinglass, as described, has ever heretofore been prepared and used in the manner herein described, and to this element and combination is due the great value of this composition over others that are well known.

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

1. A composition for surfacing blackboards consisting of black oXid of manganese and isinglass combined with other adhesive and coloring elements, substantially as set forth.

2. A blackboard provided with a surface of a composition made up of shellac, black oxid of manganese, ultramarine-blue, guiac, flour of talc, Venice turpentine, lampblack and isinglass in solution with alcohol and water, substantially as set forth.

3. A composition for surfacing or enameling blackboards consisting of isinglass and black oxid of manganese dissolved and combined with body-making and coloring elements including shellac, substantially as set forth.

4.. The process of makinga composition for surfacing or enameling blackboards in which isinglass is used as an ingredient, which consists in dissolving said isinglass in water and alcohol, and adding shellac dissolved in alcohol, and other body-making and color-giving elements, substantially as set forth.

5. The process of making a composition for surfacing or enameling blackboards which includes both isin glass and shellac which consists in dissolving said isinglass in water'and alcohol and dissolving the shellac in alcohol and combining the solutions with each other and with other adhesive, body-making and color giving elements, substantially as set forth.

6. The process of makingablackboard-surfacing composition containing shellac and isinglass, which consists in dissolving the shellac in alcohol and the isinglass in water and alcohol and then uniting the two solutions with each other and the other elements of the composition, substantially as set forth.

7. The process of making surfacing composition for blackboards, which consists in dissolving shellac in alcohol, then adding black oxid of manganese, guiac, Venice tur pentine, fiour of talc, lampblack and blue, then adding a solution of isinglass in water and alcohol, substantially as set forth.

8. The process of preparing the surface of finishing and cleaning with felt or cloth, sub- 10 a blackboard with the composition herein set stantial ly as set forth.

forth, which consists in applying said com- In testimony whereof I affix my signature position to said surface in one direction, then in presence of two witnesses.

5 rubbin down the same then applyin anw other c oat in the other direction, then rub- CHARLES EZRA GREGORY bin g it down again, and repeating the opera- Witnesses: tion until the desired thickness is secured, HARDIN LEEOH,

and then rubbing with a block of talc and W. K. PATTERSON.

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