Thread Shelf Life
Rayon thread will last on the shelf at least five years under normal conditions. If the work area is comfortable for you to work in, it's fine for the thread. Some moisture in the air is a plus. Polyester thread will last much longer. The thread is a petroleum byproduct, basically plastic. In time, the worst that will happen is that the finish will dry out on the outer layer of thread. Putting the thread in the refrigerator overnight will help to restore it. Neither should be stored in direct sunlight lest they fade. With any kind of volume you’ll use up your thread long before it dies on the shelf.
The way to economize on thread, plus eliminate the shelf life question, is to buy full 5,500 yard cones only for your staple colors (black, white, red, etc.) and popular colors (the colors for the customers for whom you do a lot of work) and buy 1,100 yard Mini Snap Cones (MSCs) for fashion colors you may never use again. You should get 1,000,000 stitches from the full sized cones and 250,000 stitches from the MSCs. What value!
As a guide-line, humidity levels ranging between 40% and 60% and temperatures ranging between 50 and 70 degrees Fahrenheit are comfortable for employees and safe for thread storage and usage. It has been our experience that, as the relative humidity increases beyond 60%, the tensile strength of rayon increases, while there has been no significant change observed in the tensile strength of Polyneon thread.
Madeira threads are sold and warehoused in all the states in the U.S., plus countries in Africa, Asia, South America and the Middle East and the tens of thousands of customers served have not reported any difficulty resulting from very extreme variations in temperature and humidity.
Thread tends to be somewhat tender. Dropping it will cause “bruising” where the thread contacts the floor. This actually creates a weak spot that can cause thread breaks during embroidering, so handle with care. And no, on the dropping!
If you have unused thread sitting on machines or shelves and not covered, your thread may get dusty and after a while the dust can eat away at the finish (the “finish” contains lubricant that’s applied to protect the thread from needle heat). Storing threads that won’t be used right away in their original containers will significantly increase usability, as will keeping them out of direct sunlight. Thread can also be stored in clear plastic stacking units, like those found at The Container Store, so that you can see which thread is inside without having to open the box.
Only semi-protected, in boxes without covers allows dust and humidity in. The next to pictures illustrate cones kept in clear boxes that protect, and have the added bonus of allowing you to see the color of the thread before opening. The only disadvantage here is that thread is happiest when it is standing up, rather than lying down.
Threads should be stored in a clean and dust-free atmosphere. Ideally, they should be stored in a warehouse or storage room that is as close to the shop floor as possible. This makes the stored thread easily accessible. And storage areas for rayon, polyester or specialty threads should be situated in areas where atmospheric pollution (such as smoke, fumes and gases) is at a minimum.