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here is how I do color matching at home. Go to michael's craft store and buy a selection of "close but not exact" acrylic enamels. I bought a few blues, greens, and a starter paint set with 20 colors.
Paint all the colors onto paper evenly but thoroughly and allow to dry. I used about 8-10 colors. You want to use maybe 2 coats for each color because you don't want any white showing through.
Photograph the frameset in bright sunlight with a digital camera and your colors painted on the paper sitting right next to the frame. Copy this digital photo onto a computer.
Edit the photo in MS-Paint and get the RGB numbers from each color. You use the sampler dropper to sample the color, and then go into "define custom color" and the existing color RGB values will be right there. Enter each color into a spreadsheet.
You now have a set of 3-dimensional vectors (your michael's colors) and the goal is to find a linear combination that matches the color of your holdsworth. I wrote a spreadsheet that would solve the 3x3 matrix, and in theory it should work for any set of "vector basis" colors like RGB or CMY, but in practice you often need NEGATIVE amounts of certain colors, which of course is impossible.
So you end up trying various subsets of 3 colors at a time to find a combination that solves the matrix with ALL POSITIVE values. In my case i was matching Carlton Lagoon Blue and for my particular palette, I got something like 3 parts blue, 2 parts GREEN, and one part white. I was quite surprised. I expected blue and yellow alone would suffice. Blue and yellow had worked wet, but it became too dark when it dried out.
This only works for flat (i.e. not candies, not pearls, not flambouyant) colors.
The best part about this system is it gives you the formula for a match when the paints are DRY. I tried at least 4 times to mix up Carlton blue but enamels change color A LOT when they dry out.
- Don Gillies
San Diego, CA, USA