[AT] Classic Blast

[james deardorff]

Bruce,
Received your e-mail.  Here are some answers to your questions.
-Yes, I do change the original blend after using 10 times.  The aluminum oxide loses I estimate 
   5% of its mass per application, there seems to be no effect on the walnut shells mass up to 
   100 uses.  So, after 10 uses I usually add 25 lbs of aluminum oxide per 8 hour day.  From 
   my use of this process over the last 8 years it seems by adding this amount per day you     never     
   run out of productive material.  (I run the used media through the cleaner I built after every 
   use to remove dust and paint chips).
-I usually set my presure at 35psi (pot pressure) for cars and 45 to 50 psi for tractors.  Nozzle 
  distance from a surface approximately 12 to 15 inches at a 30 to 45 degree angle.  For deep
   pit rust I do a primary blast at a 45 degree angle to remove old paint and surface rust, then 
   I do a 2nd blast at 90 degrees to the surface to get out the pit rust.  I have developed a "feel"
   for how much pressure to use on thin gauge metals.  I lay my hand on the metal and 
   feel the vibration.  I have done enough jobs to be able to judge pressure setting by this vibration. 
-My customers and myself have always be amazed at the way this media blend can prevent 
   rusting for extended periods of time (I have heard reports over a year).  I beleive there are 
  several reasons for this.  First, I do not produce excessive roughness like regular blasting.
   (usually less than 1 mil, 1000 th of an inch).  This gives moisture less area to bond with.  
   I have talked to several people at the Univ of Missouri about a walnut residue preventing rust.
   because of the number of times I reuse the blend that there could be much 
  walnut tanic oil deposited on the metal surface.  A phd told me that it only takes a layer one 
   atom thick to stop rust.  Also, there is no negative effect on paint because there is a greater 
  attraction to the paint than the tanic oil.  I have talked to NASA's Surface Contamination 
  Analysis Technology (SCAT Team) at Marshall Space Flight Center about this phenomenon.
   They are interested in  testing this process as a cheap and simple way reduce underfilm 
   corrosion activity for protective coating systems.  I have always felt that the use of this 
   type of cleaning could double the service life of most paint systems especially in harsh 
   chemical environments like fertilizer facilities.   
   I have written a 10 page paper on Classic Blast.  Send me an address & I will send you a 
   copy.
   Jim Deardorff




		
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