Does thread deteriorate?
 

A friend whose parents ran a draper's shop has just given me several boxes of old threads - many of them on wooden spools! There's a mix of cotton and synthetic spools. Is it likely to be OK to use, or does it deteriorate with age?

Simply do a tug test to see if it's okay.ive used plenty of threads that were 20-30 years old and just fine, I've had thread that was brand new be ( bad). It depends on lots of things. Yes, thread can deteriorate.it all depends on how it was stored, humidity, quality in the first place...
take a piece 12" or so long, wrap it between your two hands & give it a tug- if it doesn't easily break it is fine. I test every spool of thread, new or old before using. I hate starting a project and dealing with frequent breakage because it is not strong enough. I've had new, expensive thread wind up being unusable ( which I returned) and old thread work great.

I went to an estate sale last year and purchased a large gallon Ziploc bag of thread. Some had been used and some not (plastic cover still on). I do the strand test with every spool before use. So far no problems. I save the those "silica" packets that come with medicine bottles. Some spools are still in the bags. I toss the little silica packets in those bags for a little safeguarding for the used spools.

A friend gave me a lot of thread on wooden spools, and, after testing it, I use it. I have never had a problem using it. However, the testing is important because thread, just like fabric, could have been stored in such a way as to degrade it.
Be careful.

Thanks for these replies. Good news! If it's OK I'll never have to buy navy or black again!

Cotton thread does weaken & fade over time. Proper storage (kept in containers, away from UV light) does help. Typically I've been taught that you can start to get minor issues with cotton thread around the 20 year mark. Wooden spools are very likely older than that & every professional I've heard has recommended using them as decoration. In addition to the tug test, I would maybe try a sample sandwich to make sure it can handle the rigors of being run through your machine. If the thread seems to be in pretty good shape to you, the one suggestion I would add is to apply some thread conditioner to it before you start sewing. I like Sewer's Aid. You can buy it at JAF, HL or just about anywhere.

Well, maybe. Cotton thread is subject to dry rot. Also, the process used to dye the darkest colors (such as navy and black) are the most caustic and hardest on the thread. Polyester is not subject to dry rot and I think the color issue is not there for it either.

If the cotton thread was stored in boxes, then it's more likely to be fine. Cardboard boxes allow the thread to "breathe". Storage in plastic is bad for thread because it traps moisture in the thread. Moisture is very damaging to thread and fabric over time.

Where you live can make a difference. If you live in a humid climate, it is more likely that older thread will be damaged. If you live in a dry climate, thread can last a lot longer.

Google "dry rot in thread" for more info. Dry rot is actually a fungi that thrives in damp conditions. It weakens thread and the fibers in fabric.

Old cotton thread is more likely to break under the upper machine tension than when used on the bobbin. If it does not break when filling the bobbin, I go ahead and use it there.

Dry rot is a scary prospect! These threads have been in cardboard boxes in a dry environment, though of course the UK climate is pretty humid. Something to think about..

I have spools of my grandmother thread and I never use it. Thread made back in the 40s and 50s wasn't that good and I am careful with what thread I put on my Bernina.