THE MANUFACTURE OF IMPROVED PLASTIC COMPOUNDS
Year: 1883

page_text: LETTERS PATENT to Murdoch Mackay, of N° 42, Leipsic Road, Camberwell, in
the county of Surrey, Manufacturing Chemist for an Invention of "THE
PROVISIONAL SPECIFICATION left by the said Murdoch Mackay at the
Office of the Commissioners of Patents on the 20th November 1883;
MURDOCH MACKAY, of No. 42, Leipsic Road, Camberwell, in the county of
Surrey, Manufacturing Chemist, "THE MANUFACTURE OF IMPROVED PLASTIC
COMPOUNDS"
This invention relates to the manufacture of improved plastic compounds or
compositions suitable for moulding into various articles such as screw stoppers for
bottles, jars, casks and similar vessels; for the manufacture of that class of brushes
which have their bristles secured in plastic material; also for buttons, and for
various other articles for useful and ornamental purposes which are required to
stand a high degree of heat whether dry, moist or liquid.
The improved compositions are manufactured from a mixture of gum sandrac or
gum kauri, (singly or in combination) shellac, with or without rosin, carbon or
asphaltum, and asbestos or other fibrous material, or silicates.
In manufacturing a compound suitable for making screw stoppers and other
articles which require to be free from taste and smell and which are likely to be
subjected to a high degree of heat I employ the following ingredients in about the
following proportions, videlicet:-
75 pounds of lac (preferably shellac).
38 pounds of gum sandrac.
38 pounds of rosin.
38 pounds of ivory black, or other fine carbon.

page_text: this has been well amalgamated I add the asbestos or other fibrous matters or
silicates; the whole is well combined by stirring until it forms a stiff paste which
is then fit to be moulded in dies (preferably heated) or to be rolled out into sheets;
or the ingredients when heated can be mixed and worked into a paste by being
passed through hot rollers. When the compounds are required of various colours
I omit the carbon and add in place thereof any suitable colored pigments.
The above composition is not affected by either dry or moist heat at
200° Fahrenheit, nor in hot water at 210° Fahrenheit. It is not affected by the
fermentation in beer, wine and the like and is free from taste or smell when in
contact with such liquids and is specially adapted for use in hot climates.
When the composition is not required to be entirely free from taste and smell
I can use gum kauri in place of or in combination with gum sandrac, and can use
asphaltum in place of or in combination with the carbon.
The ingredients of my improved compounds and the proportions thereof above
named are those which I have found to answer well for producing compounds
suitable for the purposes mentioned but it will be evident that the proportions of
the ingredients may be varied according to the nature of the articles to be
manufactured therefrom and other recent or fossil resins may be employed either in
place of or in combination with gum sandrac and gum kauri.

page_text: 50 pounds of gum sandrac
38 pounds of ordinary rosin
38 pounds of ivory black or other fine carbon.
168 pounds of asbestos or other suitable fibrous material
or silicates.
I first put the above named resins and ordinary pine rosin into a suitable vessel
and heat the same until they are reduced to a fluid state I then add the carbon
and when this has been well amalgamated I add the asbestos or other fibrous
matters or silicates; the whole is well combined by stirring until it forms a stiff
paste which is then fit to be moulded in dies (preferably heated) or to be rolled out
into sheets; or the ingredients when heated can be mixed and worked into a
paste by being passed through hot rollers. When the compounds are required of
various colours I omit the carbon and add in place thereof any suitable coloured
pigments.
The above proportions may be in some cases varied according to the quality of
the materials employed, it being borne in mind in proportion as the quantity of
gum sandrac used is increased the heat resisting quality of the compound formed is
increased but it should not be used in excess as the result would be to give
unnecessary brittleness to the compound.
The above composition is not affected by either dry or moist heat at
200° Fahrenheit nor in hot water at 210° Fahrenheit. It is not affected by the
fermentation in beer, wine and the like and is free from taste or smell when in
contact with such liquids and is specially adapted for use in hot climates.
When the composition is not required to be entirely free from taste and smell
gum kauri may be used in combination with gum sandrac by preference in equal
proportions though other proportions may be used. Also in some cases I employ
asphaltum in place of or in combination with the carbon,
The ingredients of my improved compounds and the proportions thereof above
named are those which I have found to answer well for producing compounds
suitable for the purposes mentioned but it will be evident that the proportions of

page_text: the ingredients may be varied according to the nature of the articles to be
manufactured therefrom. In sume cases other resins may be employed in
combination with gum sandrac and gum kauri.
.
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 :-
The manufacture and use of the improved plastic compounds formed by mixing
the ingredients herein mentioned substantially as described.
•
In witness whereof I the said Murdoch Mackay have hereto set my hand
and seal this seventeenth day of May in the year of our Lord one thousand eight
hundred and eighty four
Witness
GF REDFERN
Patent.Agent.
4 South St Finsbury
London...
MURDOCH MACKAY .(L.S.)