Vintage darning thread, but first a note!
Often I'll have people ask me if they can use (specific material) for mending and I almost always say yes. Because the answer is almost always yes.
Embroidery thread? Yep. Thread? Yep. Dental floss? Great on non-stretchy fabrics. I have seen people successfully do repairs with a wide variety of things. Human ingenuity is wonderful.
Onwards
Here is an example spool of darning thread. I tried to pick the most intact one. I was organizing today and found my vintage darning thread bag.
There were also multi-color cards. Which gave you less thread, but the convenience of more colors. My card is missing a section, but I believe I have the thread for it in the bag.
And the bag! If there are any of these you want to see pictures of, let me know. I have been slowly accumulating these for over a decade. Due to the fact that I don't use them; I do only have a grocery bag full. I keep them in a gasket bin with some other stuff.
Ramble
I've had people ask if I donate these to museums for their use, but I don't. Because nothing needs it. I don't know a single museum that could use this thread.
It's old thread, but it's not OLD thread. I have gotten to own some truly old thread but I never keep it. Because it belongs in a museum. And I am not a museum.
I believe these threads are still usable. I've been tempted to test some. Should I?
if you crave owning your own old darning thread; I suggest thrift stores, estate sales, eBay and Etsy. These aren't particularly collectable, so it's usually easy stuff to get. Eventually I'd like to put a few up on my wall. Maybe just the card. Or a big shadowbox that's bug proofed.
Oh and I found these looking for the rest of my buttons. Because I will, someday, finish that dang binder. Among other things.