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Bertram31.com General Bulletin Board
Re: Gelcoat Question *LINK* *PIC*
Posted By: Capt Patrick McCrary In Response To: Gelcoat Question (BillC)
Date: Monday, 25 April 2005, at 3:13 p.m.
Bill,
The biggest pain in ass dealing with gelcoat is trying to color match new gelcoat to old...
The second biggest problem comes months later when the finally matched color no longer matches because it too has now aged...
Generally, the factory supplied new gelcoat is at least a close approximation of the original. However, if you got the gelcoat from the Bertram Factory, and it's more the color they're currently using, it's far too pink.
Colors, both gelcoat and many paints, lighten up considerably with age. Even wet gelcoat will be several shades darker than freshly cured gelcoat.
For cream colored gelcoats, the primary coloring comes from raw Sienna, yellow, & green. This is usually added to neutral base, (kind of a flesh color in the bucket).
The raw sienna will add a reddish brown tone and is complemented by adding yellow to move toward cream. A touch of brown moves it toward a tan range.
All colors are potent and must be added in tiny amounts or you'll blow right past the desired tint, tone, or shade.
When you get close and a bit darker wet, catalyze a small amount and let it kick off hard. Compare the cured gelcoat with the old gelcoat. It should still be just a wee touch darker so that it can age in over a few months.
Be sure any coloring agents you buy are clearly marked "For Use with Polyester Resins"
Unlike paints that can be color matched by a computer and blended on a color dispensing machine, small quantity gelcoats are blended by the "hit or miss" technique.
Best regards,
Patrick
BTW, I spent the better part of a week and mixed 2 gallons of gelcoat to match a house paint color for a huge fiberglass pool equipment box a few years ago. Came out an exact match, but oh boy, what a regal pain in the ass that was. Color was typical south Florida Pink Coral. Still have about a 1/2 gallon of it left.
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