Tough break, but I think it were me, I'd just try to get used to the what came back from the powder people. Once all the parts are on it, along with some bar-tape, the hue might not look so obviously wrong. I'd like to see a picture.
In a former life, I was a painter. My supplier was excellent, but there were times when paint had to be "adjusted", even though the mixing formula had been accurately applied. In addition to the paint-tech guys, there was a trained interior decorator on staff who was most brilliant at adjusting hue. She was more skilled than the actual "paint-mixers" because her training had been very much more advanced. And so sometimes I would wait until all the smocked paint-techs had gone home. Because she worked after business hours, I'd knock on the back door and she'd let me in and change the hue according to how I would describe what I needed.
The salient point is this: I forget the exact, technical terms, but the actual hue on the chip is specified by an angle at which light is reflected off the actual paint surface as tested by the manufacturer. The chip tries to translate this into something that is as close as possible. Pro-painters and amateurs alike use the same chips, but professionals get more used to translating the chip to what they imagine it will look like on the surface they intend to paint. Now, this is going back years, and computer technology might be changing how people are able to see what they are buying — I'm too far away from this stuff now to know what happens at the paint store.
Anyway, you cannot be 100% sure what a hue will look like until you get it on the wall and in the light that is reflected off it. That was why we often bought a pail of paint first instead of an 18 Litre drum — to see what it looked like on the site. Inevitably there were times when the paint had to go back to the supplier and changed by readjusting the formula. (And, by-the-way, there can be a limit to just how much you can alter a hue before you screw up the paint.) Just how well you and the supplier communicate will determine the accuracy of the final result.
In recent months, I ordered some rattle-can paint to cover some damage on my wife's Honda. I absolutely cannot tell the new paint from the old — by hue that is. Why? Because the formula is an exactly known constant, and whatever panel it is on, both the old and new are reflecting light at the same angle.
A lot of people will be thinking that one of the easiest paints to match is black. It isn't. In fact it can be a nightmare. A partner and I once looked at auto-paint chips for a black we did not have a code for. After pages and pages of different blacks we were totally befuddled. We ended up faking a repair on a black Lincoln.
Whatever you may try, things could either work out better for you — or worse! And of course, as pointed out above, adhesion and the strength of the new coating are other issues.
And some people think painting is easy!
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Vitus 979, Simplon 4 Star, Gazelle Champion Mondial, Woodrup Giro, Dawes Atlantis