November 



'905] 



THE INDIA RUBBER "WORLD 



41 



CLEANING BUILDINGS BY SAND BLAST. 



IN a previous article The India Rubber World described 

 the various methods employed in cleaning carpets, furni- 

 ture, and the interior walls of houses by means of the 

 vacuum and compressed air processes. It was shown that 

 by the use of certain apparatus all the accumulated dust was 

 literally pulled out of its place of lodgement and whisked away 

 through a line of rubber hose to a receptacle outside of the 

 building without causing the housewife or the occupant of the 

 offices where the work is done the slightest inconvenience. 



For cleaning the exterior of buildings an entirely different 

 process is necessary, for something beside dirt and dust must 

 be removed from the stone surface. In order to give the build- 

 ing that has been exposed to the storms and the sunshine for 

 15 or 50 or more years a fresh, clean appearance, similar to that 

 which it had when first erected, the surface must be scoured 

 with sand. Previous to the invention of the sand blast attempts 

 were made to remove the marks of the weather by scrubbing 

 the stone with soap and water or with chemicals in which 

 acids had been dissolved. The results were not usually very 

 satisfactory. The surface was often left streaked and discolored 

 so that its appearance was worse than before. 



It was quite evident to architects who had studied the matter 

 that a different process would have to be employed if the work 

 was ever to be done in an artistic and satisfactory manner. It 

 was a long time, however, before human invention hit on the 

 right way of accomplishing it. 



For many centuries the Arab in crossing the desert with his 

 camels had looked upon the monuments of the ancients and 

 had seen that the sand which was blown hither and thither by 

 the winds was gradually cleaning and polishing their surfaces. 

 This fact meant nothing to him because he was satisfied with 

 his manner of life, and therefore made no effort to improve his 

 condition. He would not know how to apply a scientific fact 

 to the betterment of himself or his people. 



But one day an American who was journeying across the arid 

 waste saw what the Arab had observed, and it gave him an idea. 

 If the wind can drive the sand against a stone and polish its 

 surface, why couldn't compressed air be made to do the same 

 thing? The more bethought about it the more certain he be- 

 came that such a thing was possible. 



When he arrived home in the United States he began work 

 on an invention which finally became what is now known as 

 the Sand Blast. It was a crude affair at first but was afterwards 

 improved by scores of inventors until it is now very nearly 

 perfect. 



The first and principal use to which it was put was the re- 

 moval of weather stains from the exterior walls of buildings. 

 It did its work so quickly and so well that the men who brought 

 it into use soon found that they had in their possession a big 

 money making device. 



There are now several companies in the field with sand blast 

 cleaning processes. One of the most successful is the Ameri- 

 can Diamond Blast Co., of which Franklyn M. Wise is presi- 

 dent, with offices at No. 114 Liberty street, New York. This 

 company is the owner of the Shaver sand blast machine pat- 

 ents in the United States, Great Britain, Ireland, Germany, 

 Austria, and Belgium. 



The apparatus employed consists of a portable air compres- 

 sor to which are attached as many lines of rubber hose as are 

 necessary for the work that is being done. For eight nozzles 



through which the sand is blown upon the stone surface five 

 lines of '/ inch hose are necessary. After leaving the com- 

 pressor the air is forced through a sand reservoir where it picks 

 up a quantity of sand and forces it out of the nozzles at a 

 pressure of 200 atmospheres. The sand cuts the surface of the 

 stone and removes an infinitesimal layer of its substance and 

 with it removes all stains, whether of weather or rust or other 

 discolorating elements. 



The men who operate the sand blast nozzles are specially 

 dressed for the work. Over their heads they wear helmets to 

 protect their eyes, nostrils, and face from the particles of sand 

 which might otherwise cause them untold agony. Over their 

 hands they wear soft gloves, which must necessarily be pliable. 

 The swing scafToId upon which the workmen stand is hooded 

 above and below so that the flying sand will not fall on pedes- 

 trians passing along the street below. The sand is collected 

 in the lower part of the hood and conducted through a canvas 

 tube to the ground. On a large job i 5 men are required to op- 

 erate the portable plant. Each man can clean about 500 square 

 feet of surface a day. 



Much of the success of sand blast work depends upon the 

 kind of sand used. Clean beach sand is not as effective as 

 mineral quartz owing to the fact that it may contain particles 

 of iron and moisture. If it contains iron the surface upon 

 which the sand is used will after awhile become streaked with 

 rust stains. The mineral quartz sand is, however, entirely free 

 from iron and possesses greater cutting power because of the 

 sharpness of the edges of the particles. 



The American Diamond Blast Co. has during the past few 

 months cleaned a number of notable buildings in New York. 

 Among them are the Bowling Green building, the County 

 Court house, the Hotel Majestic, office of J. Pierpont Morgan 

 & Co., and the Alexander residence, at Fifty-eighth street and 

 Fifth avenue. 



The sand blast has many other uses besides cleaning the 

 outer surfaces of stone buildings. It is employed to remove 

 barnacles from the bottoms of ships and rust scales from iron 

 bridges. The Erie Railroad Co. recently had all of the bridges 

 on its line between New York and Port Jervis cleaned by this 

 process. 



It is also used to get a proper surface for holding concrete 

 when laying foundations in damp places below the level of the 

 ground. It removes moisture, grease, or dirt that may be upon 

 it and thus give the concrete a chance to get a grip on the rock. 

 Another use to which the sand blast is put is bonding copper 

 bonds to steel rails in laying electric railroad tracks. 



Without doubt other ways for utilizing the sand blast will be 

 discovered from time to time. Already the demand for rub- 

 ber for this new use has become important, and it may reason- 

 ably be expected to grow in extent, frank l. blaNCHARD. 



Vulcanization. — Ex-Governor A. O. Bourn, president of 

 the Bourn Rubber Co. (Providence, Rhode Island) has for sev- 

 eral years past been trying a great variety of experiments in 

 vulcanization. To show the range of his work, two extremes 

 may be noted. He has certain samples of compounded rubber 

 containing no sulphur, that were left in dry heat 211 days at a 

 temperature of 105 F. and which were thoroughly vulcanized. 

 The antithesis of this was a compounded stock that vulcanized 

 in dry heat in ^ minute at 286° F. 



