Totally dumb polyurethane paint question

jtrobergjtroberg Posts: 63Member
So I had my Hudson painted with Valspar polyurethane topcoat 840, and the painter gave me a small amount of paint leftover in a can together with a can of leftover activator.  Now, a couple years later, I'd like to use it to paint a couple of extra parts rather than buy rattle cans in the same color from Paintscratch.  So my question is, can I mix the color and the activator and brush paint some small parts rather than spray it, since I don't have any spray equipment (Do I hear laughter?)? If so, is this stuff so toxic that I should not use it without a mask, filter, body suit, etc?  If so, I'll just throw it out.
Thanks for answering.  


  • D7feverD7fever Posts: 33Member
    You can use it to paint with a brush, it will probably work without the hardener.  You can use it with the hardener, but you should use a carbon filtered mask, that is rated for toxic fumes.  I have used acrylic enamel without the hardener and it works just fine, might not last 50 years. If you warm the paint a little....NOT HOT , and use a nice fine bristle brush it will come out good.  Good luck.
  • jtrobergjtroberg Posts: 63Member
    Hey, thanks very much!  I'll try it without the hardener since I have this aversion to toxic fumes.  if ii doesn't last 50 years, well, I won't be around to care.

    Thanks again!
  • bob wardbob ward Posts: 1,037Senior Contributor
    edited May 2018
    The hardener portion (usually an isocyanate) of 2 part polyurethane anything (paint, foam, elastomers) is the bit that can cause health problems. In its liquid form, either by itself or mixed with the paint, health risks from the hardener are low, given the usual provisos of safe handling procedures, don't lick it off your fingers etc. So the answer to the OP is that you can mix the 2 pack and brush it on.

    At the other end of the scale, spraying 2 pack paint without the proper protection and breathing gear, i.e. inhaling the aerosol, will cause serious lung damage very quickly. The isocyanate component of the aerosol reacts with the moisture on the lung walls and stays on the lung wall, it doesn't get exhaled. The paint also gets to stay in the lungs because its mixed with the isocyanate and eventually it does what it was going to do on the car, it sets hard, you end up with 2 packed lungs. Choose a colour you think the pathologist might like.

  • jtrobergjtroberg Posts: 63Member
    Thanks very much, Bob.  I will think hard about this before trying anything, however
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