US 1917540 A
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July 11, 1933. p, E,.PEAR$ALL 1,917,540
PLASTIC WATERPROOF COATING FOR BLASTING DYNAMITE AND THE LIKE Filed Aug. 5, 1931 Patented July 11, 19 33 UNITE STATES PATENT oFFicE DAVID E. PEARSALL, OF PITTSBURGH, PENNSYLVANIA, ASSIGNOR TO THE ENSIGN- BICKFORD CO., OF SIMSBURY, CONNECTICUT, A CORPORATION OF OONNECTIOUT PLASTIC WATERPROOF COATING FOB. BLASTING DYNAMITE AND THE LIKE Application filed August 5, 1931. Serial No. 555,234.
ly of cylindrical shape. varying from about eight inches to twenty-four inches in length and of various diameters from about one inch upward, the explosive charge being wrapped in paper, the ends-of which are folded in and the resulting cartridge coated with parafline.
'Notwihstanding the fact that the cartridges ofthis type have been in almost universal use for a long period of years, they possess inherent disadvantages, among which may be enumerated the following: The paraffine is usually of low melting point so that in hot weather it melts, causing the cartridges to stick together in the packing box. The melting of the paraffine also allows the nitroglycerine to exude through the paper, thus giving rise to a source of danger. When used in mines, the paper on the cartridges is usually slit and at times it becomes necessary to entirely remove it so that the charge may be spread inside the drill hole. It is also necessary to take into account the chemical composition of the paper casings of the cartridges in order to secure a proper oxygen balance of the explosive charger;- w
I have found that the foregoing disadvantages enumerated, and othersnot specifically set forth, can be obviated 'by the simple expedient of omitting the paper wrapper entirely and directly coating the dynamite, gclatine or other explosive with a plastic waterproof material, which is preferably of suflicient'strength and rigidity when set, to hold the cartridge in its original shape.
The coating materials which I have found practicable for this purpose are waxes, lacquers, rosins, rubber, asphalts, tars, and practically most other materials embodied in the broad class known as plastics. More specifically, the petrolatum stock waxes which have ceresine-like properties have been found par-- ticularly adaptable for this purpose since they have a relatively high melting point, are im-' inside the drill hole.
pervious to nitroglycerlne, and are frangible when suflicient pressure is applied thereto. so that the explosive charge may be easily spread I have also found that excellent results are obtainable with the cellulose acetate and cellulose nitrate lacquers. The explosive cartridge or charge may be coated by dipping, spraying, brushing or otherwise applying the plastic waterproof composition either in the melted state or in solution to a self-sustaining mass of dynamite gelatine or other explosive body and permitting said coating composition to set in in situ thereon. The explosive cartridge as thus formed has a so-called skin coating of waterproof composition which is of substantially uniform thickness throughout and which is coextensive with the explosive mass.
An explosive cartridge embodying the pres ent invention is illustrated in the accompanying drawing, wherein a self-sustaining, cylindrical mass or stick of explosive, such as dynamite A, is entirely enclosed withina skin coating B of a plastic waterproof material which is formed in situ on the mass A. The coating B is of suflicient rigidity when set to sustain the explosive charge A in its original shape.
From the foregoing detailed description it will be appreciated that the production of explosive cartridges or charges of the char.-
acter described will not only speed up the tion of substantially uniform thickness throughout, which is co-extensive with the explosive.
2. A blasting cartridge comprisin a charge of explosive of self-sustaining orm having a coating of a cellulose plastic ap-' plied directly thereto and entirely enclosing said cartridge.
4. An article of manufacture consisting of a blasting cartridge or charge of the type embracing dynamite and blasting jellies having a Wax composition coating applied directly thereto and coextensive therewith, said wax composition having a relatively high melting point.
In witnesswhereof, I have hereunto signed my name! DAVID E. PEARSALL.