Gelcoat for repairs color matching

[Elie]

My hull and decks are of different hue of white. my artistic talent being somewhat challenged, to be polite, all my tries to get a perfect match, failed miserably.
I'm looking fo a place where or a trick to get a perfect match for my gelcoat quest. My boat is a GibSea 472.

[caughtthewind]

Watch this:
https://youtu.be/MxzCZ-5lMxY

[Suijin]

As far as a place to get gel color matched, I think the best in the business is Spectrum Color. I know quite a few yards that use them to color match repairs. However, their gel is expensive to begin with and a custom color match makes it almost stratospheric.

That said, the color of your gel most likely varies all over the boat even though you don't see it. Gel fades over time from exposure to sun, and it fades down into the gelcoat layer; you can wet sand it down to what appears to the true color, but if you compare that spot to an are with the true original color, which has never seen sunlight, they will be markedly different. As a result, if you need to perform repairs on a number of different areas of the boat, using a color matching Service like Spectrum will just lead to an expensive bad result.

Your best approach is to color match each area that you need to match, right at that spot. Here is a tutorial on a very good method:

Boatworks Color Matching Gel

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A few pointers about it. "Color" of pretty much anything has two components; hue and value. Hue refers to the "tint"; red, green; blue, purple, violet, etc. Value refers to the relative lightness or darkness of a color. You can have the same hue of red but it can be light red, "full" red, dark red, etc.

The tutorial explains that a bit, but the practical issue is that when you're color matching you're incrementally getting closer in color and closer in value. As he points out, you do it painstakingly slowly when matching whites because if you go too far...put in too much color or too much darker color, you're screwed (e.g. if you need four drops of brown in a gallon of white to get your color, and you go too far, say six drops, you'd need to add another half gallon of white to get back to where you need to be.)

Another tactic is to do your color tests against existing gelcoat with a piece of plastic like mylar or something else clear and stiff. The wet blobs of your mixed gelcoat and the old deck gelcoat will have different specular properties; the plastic makes them the same so you can more precisely view and compare them.

Be forewarned. Color matching is a very time consuming process requiring patience and concentration.

[Cheechako]

I have paid to have it done twice. One was great, the other was not. Too long ago to note who did it.

[Bluemansailor]

fibreglast has over 900 gelcoat colors. Rent their book and do a color match. I have a really odd color , turns out to be "peach" but they have a perfect match.

[Elie]

Thanks you all for your ideas!
The strange thing about the 'white' colors is that it doen't exist in fact. Black is black, but white is always a mix of other colors. I took a pannel of my decks and have it 'read' by my harware paint store. It turns out that is was a mix of white 'neutral base', plus some brown, plus some black...
I wonder if pigments used for coloring house paints, would tint and mix properly with gelcoat. Alkyde paint pigments are the same?...

[doublewide]

just when I think I have a perfect color match I find that it dries whiter than it looked before it cured. One must be content with "very close, but not perfect."

[Suijin]

Originally Posted by Elie

Thanks you all for your ideas!
The strange thing about the 'white' colors is that it doen't exist in fact. Black is black, but white is always a mix of other colors. I took a pannel of my decks and have it 'read' by my harware paint store. It turns out that is was a mix of white 'neutral base', plus some brown, plus some black...
I wonder if pigments used for coloring house paints, would tint and mix properly with gelcoat. Alkyde paint pigments are the same?...

The tints that you buy for gelcoat are pretty cheap, and they last forever.

I'm not sure if regular pigments are ok as they're suspended in some sort of liquid, likely polymer. Dunno. Then again, tinting white it's literally drops per gallon so it's probably fine.

[Suijin]

Originally Posted by doublewide

just when I think I have a perfect color match I find that it dries whiter than it looked before it cured. One must be content with "very close, but not perfect."

That's the point of sandwiching the color test drops under plastic, and the existing gelcoat wet out and also under plastic. The specular reflectivity of wet gelcoat is different than after it dries. It can help you get a better match.

Also, feathering out the repair as broadly as possible helps, as it creates a gradual transition from the repair are into the old gelcoat, making it less noticeable.

[Elie]

Originally Posted by Suijin

The tints that you buy for gelcoat are pretty cheap, and they last forever.

I'm not sure if regular pigments are ok as they're suspended in some sort of liquid, likely polymer. Dunno. Then again, tinting white it's literally drops per gallon so it's probably fine.

My idea was not to save pennies, but to buy just the pigment already mixed to the right color elements by a mixing machine at the harware store and add it in minute quantities to the white gelcoat base.At least the right colors pigments would have be included. One can dream...

[Suijin]

That might work, or at least save you some effort, but it will only work for one spot. Gel coat fades unevenly across your boat. Because it's white it looks all the same and even but put a spot of the same "matched" gel coat next to repairs on different areas of the boat and you'll see the difference. In some spots the hue will have faded more and in others the relative lightness.

The best approach is always to color match, by hand, to the specific spot of the repair. If you only have one or two spots that need repair your approach might work, or not. Impossible to tell until you try.

Anyone will need a sample about the size of a quarter to do a match, so you'd need to cut that out to provide it, so there is that problem...