Never use rubber bands to store thread
This is a public service announcement to needleworkers everywhere. Share with your stitching friends. Help us spread the word that rubber bands are not good when it comes to textiles!
Keep rubber bands away from your threads. Never, ever, ever ever ever wrap them around threads that have a silver content, such as Kreinik Japan Threads, or the "J" colors of Kreinik Braids and Ribbons (001J, 002J, etc). It may sound strange to some, but we have seen this over the years: people secure their threads on a spool by wrapping them with rubber bands. Not good. The sulphur or sulphur compounds in rubber bands will cause your thread to tarnish.
Fortunately, Kreinik's black spools were designed to have their own thread-end holder: tuck the thread into the notches at either end of the spool.
You can even wrap the thread from one notch to another for added security.