PPG Concept curing question

[Bob Kane]

I guess what I did not expect was the paint gassing
off and turing solid without the hardener. Again,
using epoxy as the standard, the resin and hardener do
not "dry" by themselves (at least not in a few hours).

Thanks for the explanation.

--- Gray E Fowler <gfowler at raytheon.com> wrote:

> 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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Bob Kane
getterflash at yahoo.com


		
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