Searching for Clues in The Thread Box

Cotton ThreadGood Morning, Sleuths, Seamstresses and Spies!

We have a few first class detectives on this case:     Janice and Judy were the first to comment that C-50 and P-50 stand for threads.

Way to go, ladies!


Today, your mission (should you chose to accept it…):


Pull out every cotton thread in your sewing box.

Search out every brand, weight, ply…just one sample-not every color.   If you have Aurifil thread in three different weights, pull all three.  If you have King Tut in 5 colors, just include one spool.

I found 13 different cotton thread types from six different manufacturers in my sewing box.

Thread.LKennedy005THE SECRET CODES

Your next assignment:  List every word and marking on all of the spools:  ELS, Mercerized, 50/2, MT 1000…

Do you know what they all mean? (we will soon….)  For now, just make a list.

Each thread brand seems to have it’s own language…We need a de-coder!  (Does anyone have their cereal box de-coder ring?  Can we use it?)


Finally, separate the threads into groups by weight. 

I found five different weight categories:  60wt, 50wt, 40wt, 28wt, 12wt in my sewing box.

Thread.LKennedy008Spend a little time comparing the threads.

  • How do threads with the same weight, but different manufacturers compare?
  • Do all the cottons have the same amount of sheen?
  • Is there a difference between two ply and three-ply threads?
  • Do some threads seem smoother?
  • What other differences do you notice?

Thread.LKennedy009STITCH A SPOOL

Finally, if you have a cotton thread, 50 wt, use it to stitch The Spool onto your grid in the center box…(the square marked C-50).


  • Collect all cotton thread types in your sewing box.
  • List every “secret code” on the labels.
  • Group thread by weight and do some comparative investigating.
  • Stitch a Cotton 50 wt Spool (Tutorial HERE) into the center grid box.
  • Doodle...doodling helps improve creative thinking.  Doodle the spools on every scrap of paper, envelope and napkin that comes your way this week!

NOTE–If you have a small collection of threads, perhaps you could work on this with a quilting friend or run to your local quilt store and do a little investigating…(It’s okay to bring a few pretty ones home, too!)


This week on Open Line Friday, we will make a Master List of Secret Thread Codes…then we will work on decoding!


Tension Troubleshooting Checklist…You won’t want to miss this–unless of course, you NEVER have tension troubles!  (Which probably means you don’t sew…?)


Dr. Watson

PS…All tutorials, images and information are the property of Lori Kennedy at The Inbox Jaunt and are intended for personal use only.  Feel free to re-blog, share or tweet with attribution to The Inbox Jaunt.  For all other purposes, please contact me at  Thanks!

18 thoughts on “Searching for Clues in The Thread Box

  1. Aha!!!! I have already grouped my threads into different weights, but now will look at cotton and Poly… So very interesting!!!!

  2. I, also, love the Invisifil 100 wt… thread build-up!! One added factor: even if the weights of the threads (in the same mfr) are the same the actual thickness/diameter may vary depending on the color density! Example: white/ecru/light pastels will sew differently than intense reds/blues etc.

  3. bonjour !
    I have also 80 and 100 wt from Wonderfil …polyester !
    I put them in the bobbin and on the top when quilting in the ditch …
    aurifil is great, but lot of lint for the cotton ones …

    I am waiting for friday, because, in europe we don’t have so many threads !
    thank you !

    • Hi Chantal,
      so interesting to hear from you and your quilting experience in Europe. I recently read that Americans and Canadians QUILT, while Europe SEWS! I find that very interesting. Do you think that is true? I know Americans and Canadians DO quilt more than they sew, but wonder if you agree with Europe Sews?

  4. Lori, I love your posts. And I’m delighted that you’re making this adventure such a learning lesson! I’ve been reading all the posts. I still haven’t made my sandwich yet, but hope to do so tonight and get up to speed for the next quilting clue!

  5. I’m all caught up!!!!!!! Yay and it is totally fun…I thought the ziggities were fun! I learned something about making the thread list…don’t set your pen next to your fabric marking pen…:( !! It doesn’t look so bad now that I drank alcohol…or I mean ah…. I got i t out with alcohol…haha!!!

  6. Hi, It is funny how the subconcious works. I realized that the numbers meant weight in the middle of the night. This project has also found me in the thread drawer, organizing by type, weight, color, etc. I am still not sure. Question: what is the most common sz needle for basic cotton sewing ? #12 or 14? I’m always with a #12 but starting to ask myself if it should be 14?

    • Hi Denise. I use a lot of size 40wt threads so I usually use a size 90/14 needle. Remember the rule of thumb: Size 80/12 needle with 50wt thread. Change your needle size as a function of your thread weight.

  7. Unfortunately I am away from my sewing machine for a couple weeks, but I am very excited about this assignment. I think I may have to do some exploring of threads at the quilt shops while I am traveling.

  8. Pingback: Mystery quilt along … week five | Slaney HandCraft

  9. I have lots of threads that don’t list a weight. They are either cotton/poly blends or 100% polyester threads. Is that normal? Or, are mine so old that they are from an era before thread weights were listed on the spool??? It might be time to go thread shopping.

  10. Since we are on the threads topic…this question comes up fairly often with quilter friends and guilds- Are old threads (ten yrs beyond) good to use or not? Some say it is looking for trouble, others do not have an issue. Also some people believe that keeping thread in the freezer will preserve the quality longer. I’d appreciate feed back on that.

  11. I inherited oodles of thread from my mom..some as old as 20 years..cotton/poly wrapped. When I joined the guild 3 years ago ( after other sewing for 50 years), the ladies told me that if I hold a length of the thread approx. 20 inches long, stretched taut between my hands, pull on it, and it pops/breaks, then do not use it. I tried that once or twice and then just bought stash of new thread the colors I needed… This study is incredibly showing up how much I did not know about thread. Our local shop out here in the boonies just sells 2 brands. I suppose the answer to that is to order online?
    Thanks for the thread education…i am going to have to call you Dr Lori K. Watson, Extraordinaire PhD. me’ thinks. PS My husband keeps his childhood decoder ring under lock and key !

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