What is "hardener" in paint for?

Discussion in 'Body Restoration' started by Cardinal, Nov 13, 2011.

  1. Cardinal

    Cardinal Veteran Member Lifetime Gold Member

    Jun 22, 2003
    Endicott, NY
    Like the title says, "what is hardener in the paint for?

    Reason that I ask is because five years ago when the "friend" painted JD's custom '83 S10 (350 SBC, TH350), he left the hardener out even though we paid for the paint AND hardener! His "excuse" was that if he put hardener in the paint that he wouldn't be able to use it again!

    The paint chips easily. Just bumping into it will knock a chip into the paint. Is this because it doesn't have harnener in it?

    JD is just sick about it as he paid $3000 for the paint job. He and I both feel that we need to strip the dime down to bare metal and start from scratch.
  2. wookie

    wookie Veteran Member Lifetime Gold Member

    Jul 12, 2006
    Daytona Florida
    Old lacquer paint "Dries" by evaporation. Mix paint and thinner together and spray it on. The thinner evaporates and leaves the paint behind. The problem is, once you hit that paint with a solvent again like thinner or gasoline, it reactivates to a liquid and bye-bye paint!

    Hardener, (Or activator as it is known in the business) drys the paint by chemically cross-linking the paint into the hardener, making a urethane mix that is much more impervious to chemical attack.

    Paint will never cure fully if it is not activated. The clear is where this is the most critical. Basecoat can be sprayed without activating it. Clear cannot, unless it is old lacquer clear, which is illegal to even spray in a lot of areas.

    The S10 needs stripped and repainted to make it last. That paint on there now is doomed. Sorry to be the bearer of bad news.
    Last edited: Nov 13, 2011
  3. Marks71BB

    Marks71BB Veteran Member Lifetime Gold Member

    Said "friend" is an idiot

    Couldn't he just put a few coats of clear over it to protect the soft paint underneath. use hardener of course.
  4. Rumpity_z28

    Rumpity_z28 Veteran Member

    Jul 27, 2004
    Hope B.C.
    i think the clear would attack the weaker non cross linked paint wouldnt it? and it bubbly bubbly
  5. Chevrolaine

    Chevrolaine Veteran Member Gold Member

    Wow, some friend!:screwup: You paid for it, why should he want to use it again?
  6. Marks71BB

    Marks71BB Veteran Member Lifetime Gold Member

    I'm thinking he's not too bright. Also wondering how he knew enough to pull off a paint job to begin with.
  7. RS421

    RS421 Member

    Oct 29, 2011
    lol....maybe he should go back to painting houses? a**wipe!
  8. BondoSpecial

    BondoSpecial Veteran Member Lifetime Gold Member

    Sep 20, 2004
    Southern Maryland
    uh yeah NO to clearing over that. A paint job is only as good as the weakest link...if you clear over that sh*t when you nick it the clear AND undercoat will come off now. Not even worth wasting clear on, it all has to come off.
  9. Bikefixr

    Bikefixr Veteran Member Lifetime Gold Member

    Mar 13, 2006
    I always get a kick out of the geniuses who think they know more than the PHd engineers who spent years and millions of dollars to engineer a product. This clown shouild not be allowed anywhere near a spray gun.
  10. earlysecond

    earlysecond Veteran Member

    Aug 9, 2002
    Altoona, PA
    I am not sure what your friend was thinking. What was he going to do with the "leftover" paint YOU paid for.

    BTW harder does not get added to the gallon, it gets measured out and hardened by the mix (usually a quart or some part thereof)

    Sadly I agree with the consensus. . .it must come back off and be done properly.

    Poor analogy cause it is different BUT that is like taking one tube of JB weld, not mixing the catylist and expecting it to harden. It cannot, as Wookie pointed out the curing requires a chemical reaction. PLUS, most activitor contains chemicals which enhance shine and durabliltiy by adding UV protection.

    Sorry it happed this way for you guys. Sombody charging 3K for just a paintjob (if that was the case) should know much better.

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