there are a few of ways to go here, and I'll try and list them in order of "what you'd actually do in the real world", as some of the options can get pretty pricey, remembering that with color matching "you really DO get what you pay for"
1) computer color match: you go to a reputable "color shop" (autobody supply) and bring in a sample of the color you want matched, they scan the color into the computer, the computer chooses the closest color match from the color library, and gives the shop a mixable formula. sweet right?
the trouble with this is most times the shop needs a 4"x4" sample piece to scan, and finding 4"X4" on a bicycle just doesn't happen, so unless you have the powdercoat color shot on a 5"x5" piece of steel when you get the frame done (HIGHLY RECOMMENDED!) your going to have to go with one of the other options or you might be able to have the powdercoat shop make you a sample plate for a few bucks, or maybe free since you already got the work done.
2) "card" match: you go to the same color shop and look at the color cards (chips) out in full sunlight and compare this to your powdercoat color and choose the closest match. this actually is quite feasable provided the paint line you are working with is using actual paint and clear on the chips, and not a printed representation. R&M DIAMONT is a GREAT example of a paint line DESIGNED for card matching: all the cards are actual paint and clearcoat, and there are no less than 400 shades of each color (yup, 400 reds, 400 blues, 400 metallic blues, etc,...) so it's a little time consuming going through a couple of hundred cards till you find the one that matches perfectly, but when you do, it's usually VERY close if not an exact match, and when shot will match the card, because the card was painted, NOT printed.
PPG will often have cross referenced paint codes to match R&M or other companies paints to keep their shops from trying/using other paint lines, just call the PPG color library when you get the correct DIAMONT paint number.
3) "stick match": this is where the paint shop picks a color close to your color (you drop off the frame, or fork for them to use as a sample) and they tone that color, as wet paint in the can, matching the color on the "paint stick" to the color of the sample. this is at best a fair match, because if the paint mix guy doesn't take into consideration that all colors will darken a few shades as they dry, then you get two colors that are close, but don't match. this is especially true with reds, yellows, and any metallics/pearls and is why "stick matches" are usually free, and have no guarantee.
4) FULL "spray out" color match: this is where the color shop, mixes up the color, and sprays it on a special card, THEN shoots clear on it, lets it cure out, and then matches that in full sun. they keep shooting and adding toners till they get the shade perfect, as the clearcoat will often change a color slightly. this is the one that usually costs a few bucks (ok sometimes ALOT), and takes a day or so, but with this, you get perfect color, tone, side tone, and if your doing a metallic, you get the right size flakes, and with the proper "flop control" agents so they settle flat, and you get beautiful even metallic coverage (provided you use the proper temp reducer, and set up your equipment properly)
that should get you a PPG or DuPont paint code, and at least a pretty close match.
also make sure they ADD YOUR CUSTOM COLOR TO THE LIBRARY, and get a formula number & name it (you get to name your color too!) so you can get more mixed up later if you need it,...remembering that a pint of basecoat will cover about 4 bike frames and forks, maybe 5.
Last edited by j0e_bik3; 02-18-08 at 12:30 PM.