PPG Concept curing question

[Earl Haury]

Gray actually explains a useful characteristic of Concept. Spray a base coat, say all white, and allow this to cure for a couple of days. Then mask and spray trim color(s) and allow to dry  for a few hours. Trim color migrations via tape / mask leaks can now easily be wiped off with a mild solvent (I use degreaser) without damage to the cured base. 

Earl
  ----- Original Message ----- 
  From: Gray E Fowler 
  To: Bob Kane 
  Cc: discussion at nsrca.org ; discussion-request at nsrca.org 
  Sent: Thursday, October 20, 2005 3:22 PM
  Subject: Re: PPG Concept curing question



  Bob 

  Dry and cure are different terms. Paints "dry" which means that the paint resin is a solid at RT and it is cut in a solvent. When the solvent evaporates, a dry film of resin, pigment and filler is left behind.  The Concept resin is exactly the same...BUT the finished product adds a isocyanate curing agent which actually crosslinks the resin polymer. PPG Concept drys first to the touch then continues to crosslink react or "cure". The stuff that is dry in the can just had the solvent evaporate. 

  Try this experiment.....mix the Concept per the instructions, spray your enitre plane. After it is "dry" (1/2 hour) wipe your plane with acetone-it will wipe off. Spray your entire plane a second time but let the Concept dry AND cure then wipe it with acetone.....and it will remain. You can do this with a test coupon instead of using your plane, but the results are not as rewarding. 



  Gray Fowler
  Principal Chemical Engineer
  Composites Engineering 


        Bob Kane <getterflash at yahoo.com> 
        Sent by: discussion-request at nsrca.org 
        10/20/2005 02:51 PM 
       To discussion at nsrca.org  
              cc  
              Subject PPG Concept curing question 

              

       



  I am using PPG Concept (DCC) paints for the first
  time. I had innocently assumed since this was a
  two-part paint, it cured much like epoxy. But after
  working the stuff for a couple of weeks I noticed the
  unmixed paint in the empty cans was "dry".  So, my
  assumption is the paint will "dry" on it's own, but
  would not have the durability of properly mixed paint?
  The hardener gets all the molcules link arms and form
  a tougher material? Thanks in advance.

  Bob Kane
  getterflash at yahoo.com


                                   
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