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Yes another problem. This one has to do with non-drying poly

Discussion in 'Luthier's Corner' started by tjclem, Jan 21, 2005.


  1. tjclem

    tjclem Supporting Member Commercial User

    Jun 6, 2004
    Central Florida
    Owner and builder Clementbass
    :help: I did some spraying yesterday. Spray can poly. A can I have used several times in the last few days on a body. I re-sprayed the body then sprayed a neck I had just sanded. The poly on the body hardened just fine. The neck is still tacky. The neck is mostly hard maple with some rosewood stringers. How do I remove the sticky mess? :eyebrow: It is just 1 light coat thankfully...............t
     
  2. Use gloves & ventilate well (you must know this). If the poly is still gummy it should come off pretty easily, & the thinner will evaporate, leaving the wood clean. You may have to re-sand a bit. That's what I would do. Keep listening, though; someone may have a better solution. BTW, why did the stuff behave differently on different items? Did you shake the can for 20 minutes? Was it cold?
     
  3. tjclem

    tjclem Supporting Member Commercial User

    Jun 6, 2004
    Central Florida
    Owner and builder Clementbass
    Thanks. No I have never shaken a can for 20min.

    "BTW, why did the stuff behave differently on different items?"

    That's the part that floors me. It was in the 60's..........t
     
  4. I was exagerrating(sp?) a wee bit- maybe 12-15 minutes is sufficient. Seriously, that's just one of those little things that can make or break your day. Perhaps the poly was not mixed well; the portion that went on the body, being heavier on the catalyst side, hardened fine. The part that hit the neck may have not had as much hardener in it.
     
  5. I'll throw out my best rattle can tip - Always warm your cans before spraying. Warming them in a stream of hot water is quite safe and is practically a self regulated method since most hot water heaters are set for 110º or less. By the time it get to the sink it's down to about 104 or 105. Then shake it but you'll only have to shake it for a couple of minutes.

    I'm not kidding. If you've got ANY skills with a spray can whatsoever, this little extra step will be a leap in the quality of your coating.

    The warming thins the mixture and allows for better integration of the solvent with the solids. It also makes a finer mist in the spray and it flows out much better when it hits the substrate. I think it also conserves the propellant so that you don't run out of go blow before you run out of glow and show! :)
     
  6. Didn't think of that- good point, Hambone. I usually keep my rattle cans inside for the same reasons. A hot bath would speed things up.
     
  7. tjclem

    tjclem Supporting Member Commercial User

    Jun 6, 2004
    Central Florida
    Owner and builder Clementbass
    Tough to believe but it happened again. Same body, same neck, new can of poly. I heated the can in a container of hot water.....It did seem to spray and lay on better by the way good tip.........Same results the body seems fine and the neck is still tacky. I guess I will wipe the neck back down with lacquer thinner and the just try Qualasole on it. That is what I use on the backs of my necks as a finish coat anyway. Very strange......t
     
  8. You know Tom, you can force accelerate the drying of polyurethane like that with heat. I use one of those oil filled heaters (so there's no open flame - yikes!!) and I'll hang my body or neck above one of those so they are in a nice column of quite warm air. Sometimes I've left them for 24 hours like this and come back to an extemely hard cured finish in the coldest or high humidity weather.

    Logic is telling me that there isn't anything wrong the the poly if the body is curing right. :eyebrow:
     
  9. Bassic83

    Bassic83

    Jul 26, 2004
    Texas, USSA
    Tom, how much rosewood is in the neck? Is it fully cured, or oily? The oils might be reacting with the poly, not letting it dry right. Just a thought, I might be way off on this one, but I thought I'd throw it out there.
     
  10. tjclem

    tjclem Supporting Member Commercial User

    Jun 6, 2004
    Central Florida
    Owner and builder Clementbass
    The neck has rosewood stripes not very thick and it is from the same board as the fingerboard. I radiused the fingerboard and it didn't clog the paper. The rosewood seems to be dry. I cleaned off the poly off that neck and did the qualasole on it. A few more coats tomorrow and it ought to be fine. I sprayed the neck for the spalted bass today and it is doing the same thing. I am using a heat gun very gently to try and getit to cure. Very strange..t
     
  11. which wood is body made of?
    One thing i learned on MIMF (taking Hambones advice) is always try your finish on scrap
    If neck and body are different woods, there's the catch. But if not.... well use nail polish :D
     
  12. tjclem

    tjclem Supporting Member Commercial User

    Jun 6, 2004
    Central Florida
    Owner and builder Clementbass
    the body is the spalted on in the other thread. I did get the heat gun to cure the spalted's neck...........t