IMPROVEMENTS IN THE MANUFACTURE OF COLORED PENCILS LEADS OR CRAYONS
Year: 1885

page_text: COMPLETE SPECIFICATION,
I JOHN HENRY JOHNSON of 47 Lincolns Inn Fields in the County of Middlesex
Gentleman do hereby declare the nature of said Invention for "IMPROVEMENTS IN
THE MANUFACTURE OF COLORED PENCILS LEADS OR CRAYONS " which Invention
has been communicated to me from abroad by the Eagle Pencil Company of the
City County and State of New York in the United States of America Pencil
Manufacturers, and in what manner the same is to be performed to be particularly
described and ascertained in and by the following statement :—
This Invention has reference to the manufacture of pencils both slate pencils and
pencil leads or crayons and it has for its object to produce a colored pencil that is
to say a pencil which instead of making the usual white or nearly white mark of
the ordinary soap-stone or slate pencil or the usual black mark of the lead or
graphite pencil will make a mark in color as for instance red blue or green.
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This result is obtained according to this Invention in the following manner,
For the base of the composition of which the pencil is made, talc or soap-stone
and potters clay are used. The coloring matter consists of a mineral color or a
color that will resist for the requisite length of time without appreciably fading,
the considerable heat to which the pencil must be subjected, Among such colors
may be named iron-red, ultramarine, burnt sienna, Indian red-chrome and minerat
yellow, (a mixture of the two should be used inasmuch as chrome yellow alone will
not withstand so well the heat and what is known as "Victoria" "permanent" or
lump" green. For modifying the shades of color a little graphite may be added
to any one of the colors or mixture of colors.
"
The proportions in which the ingredients are taken can be considerably varied.
One formula that gives good results is as follows.

page_text: the pasty mass thus produced is pressed or moulded into the requisite shape The
press which may conveniently be employed for the purpose consists of a cylinder
having in its bottom a hole or dye opening of the size and shape suitable for the
desired cross section of the finished article.
The compound in plastic condition is put into the cylinder and is squeezed out
through the opening by means of a piston or follower actuated by hydraulic
pressure or other suitable power. The mass thus emerges from the press in the
form of a continuous stick which is deposited upon a tray or support and cut up
into proper lengths which are allowed to thoroughly dry and as soon as the drying
operation is completed the lengths are baked in a furnace. In carrying out the
baking operation the furnace or baking chamber should first be raised to a bright
red heat then the dried sticks or pencils are placed therein and allowed to remain
say about 10 minutes or until they are heated to a dark or dull red heat. They
are then at once taken out and allowed to cool.
For the manufacture of slate pencils this completes the operation and the result
is a composition pencil similar in structure and hardness to a slate .pencil and
susceptible of being put to like uses, but making a coloured mark. (red blue green
or yellow for example) according to the particular color employed in the manufacture
of the article.
For the manufacture of colored pencil leads or crayons the process'is' carried one
step further, that is to say after the above recited series of operations has been
gone through with the baked article is boiled in fat or oil such for instance as
stearine which on the whole is best calculated for the purpose. The article is
immersed in the boiling stearine and is there allowed to remain for twenty minutes
or thereabouts. This operation changes the characteristics of the article and converts
it into a pencil lead or crayon which is quite as good as and in some respects
superior to ordinary colored leads or crayons.
The latter are made usually of coloring matter, kaolin and a binding medium
such as gum tragacanth, the composition owing to the gum it contains cannot be
baked but must simply be dried, and the gum affects oftentimes the quality of the
article.
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The colored lead made by the improved process contains no gum and being baked
is stronger than a lead or crayon that is merely. dried and it consequently can be
made of as small size as ordinary graphite pencil lead, which is not feasible with
colored leads of ordinary make Moreover the marks made by it can be readily
erased without smearing or soiling the paper which is not the case with ordinary
colored leads or crayons.
The formula herein before given will produce what is known to the trade as a
"medium" soft lead By increasing or decreasing the quantity of potters clay the
lead will be rendered proportionately harder or softer.
Having now particularly described and ascertained the nature of my said
Invention and in what manner the same is to be performed I declare that what
I claim is
心
The manufacture of colored pencils as and possessing the characteristics herein-
before set forth..