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Old 28-03-2010, 11:59   #1
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Gelcoat Pigments

I have started doing some gelcoat repairs trying to match the of-white colour of my boat.
Last year I did the stern mixing cream gelcoat with white and it came ok.

But I think I ll try a different approach this year. So,
the question is can I add pigments ie grey to white gelcoat to match the colour of my boat?
Can I also use pigments from artists shop which are cheaper and available everywhere and what kind should I look for?
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Old 29-03-2010, 10:03   #2
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You can use any pigment but should know that you're probably the first to try that and see how it holds up in UV. I would buy a little kit of pigments for polyester gelcoat and these are not very costly and available everywhere.

I must also state that I utterly failed to match colors so if you got good results before, I would stick to that like there's no tomorrow. ;-)


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Old 30-03-2010, 19:19   #3
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If your boat has a white to beige gelcoat, the 3 main tints are yellow, black and perhaps brown (also called sienna or burnt umber - can be purchased from any paint store and hold up). Red can also be mixed in as it is sold with a lot of kits but burns out after a few years from UV.

Always work Down to the color - if it's too dark its hard to make the mix lighter again. So after every addition of tint to the white, make a small sample on a white piece of cardboard till you get close and hopefully right on..

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Old 27-04-2010, 12:14   #4
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Thank you indeed.
That is very helpfull.
Are these colours water soluble pigments? What type of colours am I looking for to purchase?
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Old 27-04-2010, 14:26   #5
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Pigments are typically dry powder while the colourants used by paint stores are immersed in a vehicle (usually glycol as it can mix into water or oil based paints). Go to a paint store and see if you can buy a little off them. The 3 colours silver40 mentioned should be all you need for most off whites - thats yellow (a mustard type usually called oxide yellow or something like that) black or grey and burnt umber. You also might want to google the colour wheel. If you have too much of a colour you add the colour opposite on the wheel to cancel it. Most importantly go slowly - you can always add more colour but you can't take it out.
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Old 02-05-2010, 11:38   #6
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Longtime color matcher here. Make sure you match to an area of the hull near your repair that has been wet sanded and buffed to bring it to its original color. Otherwise you will be matching to your oxidized hull. And definitely match close to the area you are going to repair-its amazing how much color difference you can get between areas that are in theory the same color. And finally, the secret to good color matching. It's hard to explain in text but i'll try. Cut up some pieces of CLEAR mylar about 1" square. If you cant get any cigarette cellophane works fine. After wet sanding and buffing the area you will match too, start mixing your color. When you think you are close, daub a drop or so onto the spot you are matching to. Then take a square of mylar and lick one corner of it to get some spit on it. Put the dry corner of the mylar onto the gelcoat drop and the spit corner onto the surface you are matching to. Then gently tap the mylar until the gelcoat and the spit run into each other. This will give you a clear hard line between your match color and the original color of your hull, allowing for a comparison. It's hard to explain why this works, but believe me it does. I've done thousands of matches this way, it's an old pros trick. People bring their color matches to me instead of the computerized matching people because the computer never gets it quite right, whereas my matches are almost always perfect. Even on colors other than white. Try it and you'll see why it works. Prep good and have fun!
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Old 02-05-2010, 19:54   #7
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Camd has the key explanation - Pigments are dry powders that are mixed into a medium or vehicle to make them liquid. Polyesters pigments are different from epoxy pigments and you cannot use them interchangeably. One of the vehicles in polyester pigments is styrene which is absolutely not compatible with epoxy.
- - So use the proper type of pigment for the resin you are using which in the case of "gelcoat" is polyester resin.
- - It is an "art form" to be able to match new gelcoat to old gelcoat. Any "wet" pigmented product will dry out lighter than what you think you mixed. That is the same whether you are painting a portrait or house or patching colored gelcoat. The "art" is knowing how much more/less you have blend the color so that it drys/cures to the existing color. Not for the faint of heart as you will spend a lot of time sanding off the patch because the colors do not match.
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