My method is to create a string of 4 – 6 numbers for each key (based on the amount of teeth and depth of the teeth) and associate each lock with that series of numbers. I trained myself to do this in high-school (the story behind that is beyond the scope of this thread but you can click here to read that story). I’ve had many keys over the years, never used a color coding system and rarely inserted the incorrect key into a lock.
