Method for removing surface coatings

Abstract

A method of removing a coating, such as paint, varnish, biological growth or grime, from a surface, the method comprising selecting a suitable particulate solid having a particular, size of from 150-250 mm and a fluid carrier to form a spray mixture and spraying the mixture as a jet spray so as to impact and at least partially remove the coating. The hardness of the particulate solid is less than 8.0 on the Moh scale. The pressure applied to the spray mixture to generate the spray is from 3.sub.x 10.sup.5 to 1.5.sub.x 10.sup.6 Nm.sup.-2. An apparatus comprising a blasting pot ( 1 ) and a compressor ( 2 ) to generate the spray mixture and propel it from a nozzle ( 5 ) is also disclosed. Heating may be applied to the carrier, either prior to or when mixing with the particulate solid.

1 . An apparatus for removing a coating from a surface, the apparatus comprising:
 a blasting pot including an inlet pipe and an outlet pipe including a nozzle, the blasting pot holds a mixture consisting of a particulate solid and a liquid, wherein the particulate solid includes a particle size of 150 to 250 μm and a hardness less than 8.0 on the Moh scale;   a compressor for pressurizing the blasting pot; and,   an inlet valve operatively connected between the blasting pot and the compressor;   wherein compressed air is provided to the blasting pot via the compressor, wherein the mixture is sprayed from the nozzle at an approximate pressure of between 4×10 5  to 1×10 6  Nm −2 .   
     
     
         2 . The apparatus of  claim 1  further including a means for heating the liquid, wherein the fluid is heated to a temperature between approximately 25 to 40° C. 
     
     
         3 . The apparatus of  claim 2  wherein the means for heating the liquid is a heating element within the blasting pot. 
     
     
         4 . The apparatus of  claim 2  wherein the means for heating the liquid is a heating element operatively attached to a fluid inlet supply, which is connected to the blasting pot. 
     
     
         5 . The apparatus of  claim 1  wherein the liquid includes organic or inorganic solvents. 
     
     
         6 . The apparatus of  claim 6  wherein the organic or inorganic solvents include alkyl alcohols. 
     
     
         7 . The apparatus of  claim 7  wherein the alkyl alcohol includes ethanol, propanol, iso-propanol, ethylene glycol, or propylene glycol. 
     
     
         8 . The apparatus of  claim 6  wherein the organic or inorganic solvents include acetone, butatone, or sulpholane. 
     
     
         9 . The apparatus of  claim 1  wherein the particulate solid includes olivine, andalusite, spodumene, diaspore, congolite, spessartine, or andesine. 
     
     
         10 . The apparatus of  claim 1  wherein the particulate solid includes a man-made material having the requisite hardness.