The issue of variations between one paint sample and the next are a significant issue.  Without samples which are exact matches from the paint manufacturers, the color samples in our database may fall on one extreme or another of the potential suitable paint matches.  A problem, to be certain.

The solution though is in simple statistics.  By getting as many samples of each color as possible, they can be averaged and should reveal a point in the middle of the paint samples that is the actual master color.

In this regards, we do need your help.  If you have found this tool to be useful, please consider donating a few drops of paint to the cause.  You can contact me and I will arrange to send sample materials to you as well as instructions to get the most uniform set of paint colors.  When the new samples arrive here, they are added into the database and averaged along with the others already in the database.  The end result of course is a more accurate and useful tool for everyone.