Gelcoat colour analysis by camera?

Discussion in 'Fiberglass and Composite Boat Building' started by Nick.K, Feb 25, 2018.

  1. Nick.K
    Joined: May 2011
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    Location: Ireland

    Nick.K Senior Member

    Recently I have been doing some colour gelcoat repairs mixing the colours by trial and error. The results are reasonably good but it is really slow and it's frustrating to start again if I find I haven't mixed enough.
    I have seen adverts for colour matching where you send off samples but it occurred to me that it may be possible to do this with a digital camera if the white balance was set against a known hue for the lighting conditions on site.
    Has anyone here any experience with this or recommendation for a repeatable method of colour mixing?
     
  2. gonzo
    Joined: Aug 2002
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    gonzo Senior Member

    It is possible, as long as you have a way of calibrating the equipment. However, gelcoat is usually not uniform in color, so it needs to be blended into the area to be repaired. There are many companies that sell color match if you give them the manufacturer, model and year; just like for cars.
     
  3. ondarvr
    Joined: Dec 2005
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    Location: Monroe WA

    ondarvr Senior Member

    You can get a color eye and the software to do matching, but it's pricy, sending pics doesn't work well. The software is calibrated to the exact pigments you have available, even to the exact batch, then tells you how to get from point A to point B with those pigments. If you have two sets of software so you can reproduce the same color at two locations, the two systems need to have their calibration synced to work with each other, and even then it won't be perfect.
     
  4. DSR
    Joined: Mar 2017
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    DSR Junior Member

    Hi Nick,

    I'm not sure how closely gelcoat pigments would follow automotive paints, but some of the larger body shops or paint supply places with their own paint mixing systems, use a type of spectrometer that actually analyzes a finish and creates a "recipe" of pigments to exactly match the color, even correcting for oxidization if the finish is older. It might be worth checking with some of the shops or paint suppliers locally?

    Thanks,
    Dave
     
  5. gonzo
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    Location: Milwaukee, WI

    gonzo Senior Member

    They use the same pigments. However, they need the software to account for what type of base is used. I think clear gelcoat may be pretty close to a neutral base.
     
  6. ondarvr
    Joined: Dec 2005
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    Location: Monroe WA

    ondarvr Senior Member

    They don't use the same pigments, although some could be compatable. The resin base used to carry the pigments is different too, small amounts of many things can be added to gel coat and you may not see any noticeable detrimental effects, but not knowing what the effects might be is a risk.

    There are portable hand held color eyes (spectrophotometers), but to use the color values from them to match colors you need to have it calibrated to the one in the lab.
     
  7. Nick.K
    Joined: May 2011
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    Location: Ireland

    Nick.K Senior Member

    Thanks for the replies.
    The boat I'm about to start gelcoat work on was built in 74 so it's very unlikely I could get an off the shelf match. As Gonzo says, in any case there are slight differences in colour over the hull even after cleaning. In general the gelcoat is surprisingly good but there are a few areas where the hull was scratched through to the laminate and the then-owner tried hard to polish out the scratches :confused:!
     
  8. gonzo
    Joined: Aug 2002
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    gonzo Senior Member

    The easiest thing if there are many areas to repair is to spray the whole hull. At the end, it is faster and cheaper.
     

  9. PAR
    Joined: Nov 2003
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    Location: Eustis, FL

    PAR Yacht Designer/Builder

    Color matching gel coat is a bit of a black art and you just need serious experience with it. Even with this, you'l still often have to consider the big picture and end result, which may be a whole side or transom, etc., instead of trying to blend in spot repairs.
     
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