This article tells you about color coding solder chips, why and how.
Let’s face it, not every snippet of solder winds up in your work. Some pieces fly away during clipping, while others jump on the floor or fall into your catch pan, never to be found again. You might even accidentally spill one tray of solder snippets into another, mixing two different grades and creating a useless chaos. (After all, unless you are 100 percent sure which grade of solder snippet you have, you cannot use it.)
To make your life easy, color code all your solders when you first get them. Use fat permanent marking pens of various colors to indicate the melting temperature. For instance, use red ink to cover both sides of your hard solder sheet (the hottest color for the hottest flow temperature). Use black ink for medium, and use blue or green ink for easy solder (the lowest flow temperature). Cover both sides completely.
When you need solder, cut a piece off the appropriate sheet (hard, medium, or easy). It is now simple to find and identify solder snippets, no matter where they fall. And the ink burns off cleanly a long time before the solder begins to flow.