Recently I received a fabulous package from Mom containing some fiber finds from her most recent tag sale adventures. In addition to some lovely fabric, she sent me a whole bunch of thread. Much of it was 100% cotton. Based on color alone I would definitely consider quilting with the cotton threads. But I'm concerned about the age of the thread. How can I tell if I should use it? 
I'm not just being ageist. Somewhere in my quilting education a wise woman said that thread can dry out and lose its strength over time, so beware of using great-grandma's thread collection on your quilt. Much depends on the quality of the storage. Given that this was a Floridian tag sale find, I suspect there was plenty of moisture in the air where this thread was stored. As you can see, much of it is wound on beautiful wooden spools, so even if the thread itself is no good, I'll certainly use the spools for winding handmade trims and whatnot.I'm not going to shell out $42 for ASTM's Standard Test Methods for Sewing Threads, but the description shows that they measure colorfastness, shrinkage, strength and elongation, loop strength, and knot strength among other properties. The peanut gallery at Askville seems to favor the pull until it breaks test. Elphaba over at PatternReview.com favors the bobbin winding test. If I were super cool, I would break out a microscope and check out the quality of the thread under 60x magnification like Debbie Colgrove over at sewing.about.com.
First, I did a snap test like the peanut gallery at Askville suggested. I wound the ends around my index fingers like I was preparing to floss my teeth. I put my index fingers together. Then I moved my index fingers apart as fast as I could. I did this with a few different strands of the tag sale thread and a few strands of brand spanking new thread. Same results. So far, go old thread!
Second, I wound a bobbin at full speed from one of the spools of old thread. No problemo.
Finally, I used the thread to finish the edges of some flannel to make reusable wipes. I sewed at CRAZY high speeds. I don't usually sew that fast, so I'm not sure if it was the thread's fault or mine, but I did experience a few thread breaks over the course of maybe 10 bobbin's worth of sewing. I washed the resulting wipes on the sanitary cycle of my washing machine and dried it on high. No color ran and there was no discernible shrinkage.
Final verdict: yay, old thread!
For more information on thread, check out YLI's A Thread of Truth (PDF) which I discovered via Pin Tangle.
