even if you had a tin of paint from the original batch, it doesnt guarantee a perfect match, as diferrent nozzles and air caps, hotter spraying conditions, higher air pressure etc etc can cause colour differences. i remember having a capri painted many years ago , they had the fuel flap off the car hanging up ,it was sprayed at the same time as the car, the same number of coats, when it was refitted to the car it was a mismatch.... it had been hung the wrong way up , so when turned through 180 degrees the metalic flakes looked different to the rest of the car, used to really niggle me. the od fashioned nitro cellulose systems dried by evaporation of the solvent, the gun finish synthetics , air dried by oxidation of the binder, whereas the modern 2 pack systems are chemically hardened with the addition of an isocyanate hardener / thinner and low bake oven process. matching techniques as i stated in other paint related posts from what i have seen are not half as much of a problem as they used to be. Solid reds used to be an absolute nightmare as they woud drop, ie darken as they dried often over a few months, we have all seen cars that have had various panels repainted that may have been a perfect match when they came out of the painshop, but see that car 6 months down the line, especially under orange street lamps and it would look a patchwork of diffierent shades of red. this also applied to any colours with red in the mix, ie beiges for one so I quickly realised that it was a trade in which it is very hard to keep people happy in, as cars that had gone out perfect, to customers that were absolutely thrilled at the time , would later be a mobile advert for your bodyshop that ended up looking like you had put out a car with a terrible colour match. the job that convinced me of that was a convertible morris minor, in rose taupe, a sort of pinky ,peaty, monkey s**t brown colour, i repaired the rusty sills and edges of the wings and blew in the bottom 18 inches all around, the match was 100% spot on and even I as the sprayer couldnt see it. 6 months later, that car looked like it had been blown in by a novice with an aerosol. I now move pianos for a living, much easier,..........till you get stuck on a fire escape with a seven foot bechstien and the sky opens up.
