Pianotech

  • 1.  Colour-matching Samick Polyester

    Registered Piano Technician
    Posted 06-10-2017 22:44
    Hello all,

    I am doing a polyester repair on a 1994 Samick grand piano lid, filling a fairly deep gouge with liquid polyester. The part of the repair that is going over a thick layer of original polyester is coming out OK, but the part that has a thick layer of new polyester is ending up slightly translucent with a maroon tint to it, similar to how a Sharpie can be kind of blue. I am using 3 drops of Intensive Black and 3 drops of Asian Black. What am I missing? Higher concentration of colour? Different ratio of pigments? Rex-Lith instead of liquid?

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    Peter Stevenson RPT
    P.S. Piano Service
    Prince George BC
    250-562-5358
    ps@pspianoservice.com
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  • 2.  RE: Colour-matching Samick Polyester

    Posted 06-10-2017 23:49
    Rex-Lith won't have the gloss. Try four drops of each color, I've been having good results tha tlook good through the sanding process but I haven't brought it to a polish yet.

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    Regards,

    Jon Page
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  • 3.  RE: Colour-matching Samick Polyester

    Registered Piano Technician
    Posted 06-11-2017 00:45
    You might try contacting Ruth Zeiner who sells the Konig polyester. She will have a straight answer for you.
    Good luck.
    Paul McCloud
    San Diego




  • 4.  RE: Colour-matching Samick Polyester

    Registered Piano Technician
    Posted 06-11-2017 09:46
    Thanks, Paul. I did contact Ruth, but since I am working on this over the weekend, I was hoping to hear back from other experienced techs in case I didn't hear back from her until Monday.

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    Peter Stevenson RPT
    P.S. Piano Service
    Prince George BC
    250-562-5358
    ps@pspianoservice.com
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  • 5.  RE: Colour-matching Samick Polyester

    Registered Piano Technician
    Posted 06-11-2017 10:45
    Got it. I don't know the age of your piano, but some years ago when I worked for the Samick dealer, I used to use the Intensive Black. I don't know about the Asian Black. You have to be a little careful not to use too much color or the polyester won't catalyze properly. I always measure the resin very carefully and add just enough pigment to make the mixture opaque. Usually I use those small plastic medicine cups and maybe 1/4" or less in the bottom of resin. Then add 3 drops of Intensive Black, and mix it up. I tip the cup and watch the colored resin as it drains to see how opaque it has become. I use maybe 3mm diameter ball of hardener. If you have high humidity, it will slow down the hardening process. You can use more hardener in that case. In small quantities, it's easy to overdo it and it will smoke. Some of the colors are tints (no pigment), so that may affect how much opacity you get. It may look black, but unless you have enough pigment you'll get a different result. On Asian pianos like Yamaha they have a Yamaha black, but I usually have to be careful not to use too much or the liquid will prevent it from hardening properly. I use a couple of drops of Intensive Black along with it, even though it has a slightly bluish tint (Yamaha is definitely gray). Most of the Chinese black poly pianos are also a gray color, so I use that on them also.
    That's all I know. Good luck.
    Paul




  • 6.  RE: Colour-matching Samick Polyester

    Posted 06-11-2017 10:59
    Black isn't black when it comes to transparent dyes. Try Mohawk M520-2246 a pigmented colorant. Mixes with lacquer, epoxy, and fiberglass resin. I've been mixing it of late with west system epoxy. Very opaque, great stuff.





  • 7.  RE: Colour-matching Samick Polyester

    Registered Piano Technician
    Posted 06-11-2017 11:38
    Peter-
    You might also try to color the repair prior to filling with the liquid poly.

    YMMV.

    Good luck!~

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    David Brown
    Dallas TX
    214-288-9413
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