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 x 10 5 to 1.5 x 10 6 Nm −2 . An apparatus comprising a blasting post and a compressor to generate the spray mixture and propel it from a nozzle is also disclosed. Heat may be applied to the carrier, either prior to or when mixing with the particulate solid.

1 . A method of removing a coating from a surface, the method comprising: 
 (i) selecting a particulate solid suitable for removing the coating from the surface, the particulate solid having a particle size from 150 to 250 μm;    (ii) selecting a fluid as a carrier for the particulate solid;    (iii) heating the fluid to a temperature of from 25 to 50° C.;    (iv) distributing the particulate solid in the fluid to form a spray mixture;    (v) generating a pressurised jet to the spray mixture;    (vi) impacting onto a coating the pressurised jet of spray mixture to remove the coating.    
     
     
         2 . A method according to  claim 1 , wherein the particulate solid has a particle size of from 170 to 190 μm.  
     
     
         3 . A method according to either  claim 1 , wherein the hardness of the particulate solid is less than 8.0 on the Moh scale.  
     
     
         4 . A method according to  claim 3 , wherein the hardness of the particulate solid is from 6.0 to 7.0 on the Moh scale.  
     
     
         5 . A method according to  claim 1 , wherein the particulate solid is olivine.  
     
     
         6 . A method according to  claim 1 , wherein the fluid is a liquid.  
     
     
         7 . A method according to  claim 6 , wherein the liquid is water.  
     
     
         8 . A method according to either of claims  6  or  7 , wherein the solid to liquid volumetric ratio in the spray mixture is 2:1.  
     
     
         9 . A method according to  claim 1 , wherein the mixture is directed so as to impact the coating at an angle of 45°.  
     
     
         10 . A method according to  claim 1 , wherein the jet spray is moved, in use, in a circular motion back and forth across the coating.  
     
     
         11 . A method according to  claim 1  where the pressure is from 4 x 10 5  to 1 x 10 6  Nm −2 .