US1288792A - Stencil-sheet. - Google Patents

Description

'nnirnn snares Parana. oration.

JAMES A. AMIBLER, 0F NATICK, MASSACHUSETTS.

STENCIL-SHEET.

No Drawing.

To all whom it may concern:

Be it known that I, JAMES A, AMBLER, a citizen of the United States, residing at Natick, in the county of Middlesex and State of Massachusetts, have invented certain new and useful Improvements in Stencil-Sheets; 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.

This invention relates to stencil sheets which are commonly used for typewriting duplication.

A form of stencil sheet now commonly used in typewriting duplication consists of a sheet of Yoshino paper coated with a coagulated colloid, such asgelatin, vegetable gums, Irish moss, etc., which colloids have been treated with glycerin, formaldehyde, and potassium bicromate. 'Before a sheet of the above character can be used for type- Writing duplication it must be moistened to place the coating on the paper in. condition to receive the indentation of the type and to avoid cutting or breaking the fiber of the paper. To properly moisten such a sheet requires care and often occasions delay and inconvenience Further. all of the wellknown processes of making gelatin-coated stencil-sheets employ a large quantity of glycerin.

The primary object of the present invention is to provide a stencil sheet and process of making the same which will overcome the above objections and produce a stencil sheet which is durable, efficient, and will remain in condition for immediate use without nioistening.

In accordance with this ob one feature of the invention contemp coating a sheet of open, porous material with a film of gelatin which is impregnated with a hygroscopic metal chlorid, and then before the sheet becomes hard treating it with a dilute solution of glycerin to keep it soft and pliable. The glycerin is a hygroscopic, trihydric alcohol, and when used with a hygroscopic metal salt, such as calcium chlorid, the two ingredients tend to hold Specification of Letters Patent.

Application filed December 29, 1915.

Patented Dec. 24l,'1l9il&

Serial No. 69,225.

the sheet in a soft, damp condition so that the colloid will be permanently in condition to be displaced by the indentation of the type without destroying the fiber of the paper base.

In carrying out the process, a paper base such as Yoshino or similar paper having a loose,-coarse texture, is first passed through a bath containing. a solution having approximately sixteen parts of gelatin and three and one-half parts of calcium chlorid dissolved in two hundred and twenty-four parts of water, preferably distilled. These proportions may be varied to quite a degree without materially altering the product. After the sheet has passed through the calcium chlorid bath and allowed to drain, it is next passed into a dilute glycerin bath containing approximately four parts of glycerin and fourteen parts of water.

After the sheet has drained and dried it is soft and pliable and feels slightly moist to the touch. The paper is very tough and is in a condition so that it may be used immediately to receive the impression of characters of type. With the first treatment of gelatin and calcium chlorid, the paper base becomes thoroughly impregnated with the.

mineral chlorid and then the treatment with glycerin converts it to a tough, pliable sheet. The hygroscopic properties of the chlorid in conjunction with those of the glycerin hold the colloid on the surface of the sheet permanently in a condition to be displaced by the indentation of type of a typewriter. The calcium chlorid also has preservative properties in preserving the life of a colloid and greatly reduces the amount of glycerin need-ed to keep the sheet in a moist condition.

Having thus described my invention. what is claimed as new, is

1. The process of making a stencil sheet which comprises, passing a base of open, porous material through a solution of gelatin and an alkaline earth chlorid. and subsequently passing the treated base through a solution of glycerin.

2. The process of making a stencil sheet Which-comprises, passing a base of open, porous material through a solution containgelatin and three and one-half parts calcium chlorid in two hundred and twenty-four parts of water, and subsequently passing the sheet through a bath containing a dilute glycerin solution having four parts of glycerin in fourteen parts of water.

' JAMES A. LER