A Sewing Lesson

I learned a sewing lesson and I wanted to share it with all of you.

Do not sew through the iron-on patches.
That is it. So, you can just file that away and stop reading if you would like.

In our house there are some good old jeans that seem too precious to part with, but when they actually spring a hole in them, they are no longer deemed acceptable to wear out of the house. (By the inspector general. That is me.)

I set about to make them passable again. First, I ironed on some strips of patch fabric. Then I put them “under the needle” to make some reinforcing rows of stitches and my machine got fouled up. I re-threaded my machine and started over. But the same thing happened.

The needle kept getting gummed up. So I changed the needle to a thicker, denim needle thinking that maybe there was a burr catching the fabric. But the new needle had the same issue.
Here is what the bobbin was doing:

Freaking out. As if the tension was set to zero, but it wasn’t. The thread was getting stripped, but staying in the needle. The needle moved up and down like normal, but no new thread was feeding in, so essentially, it was behaving as if the tension WAS set at 0.
I tried turning the pants over, and putting the patch down to face the bobbin. I thought that maybe the stringy nature of the rip was allowing the threads that were hanging down to get caught in the bobbin, and confusing the machine.

But even putting the smooth side down and running the needle over the fringy denim didn’t work.
It finally came to me that the gum on the back of these patches was actually building up on the needle and forming that ball. I waited for a while, thinking that after the patch had cooled, the adhesive would be more “set” and the needle would travel through without picking so much of it up. Four hours later, the issue persisted.
We are back to the lesson: do not sew reinforcing stitches through iron-on patches. They are just meant to be knee patches. The gum adhesive never solidifies. It leaves a coating on the needle and grabs the thread. The plies of the thread split, a ball builds up on the needle and the whole operation comes to a halt.