I came across some linen hand towels back in the 70'sa when I first got started in this hobby. It did not take long before I was looking for MORE of that material or other materials and came across some 'brushed denim' I measured at .022" compressed hard. Once washed, this soft fuzzy sided denim was very supple. Both Taylor and I found it to be a good patch. This set me off on a long love affair with this 'weight' of denim - an affair that's still an ITEM on today.
Since the 70's, I've only found one material that is equal to or better than denim although I've spent a lot of time and years searching.
The one I found that is as good, perhaps even better as it is softer, was that railroad mattress ticking, red/light blue,white/dark blue ticking. The lady in the yard good store called it denim, but it did not have a denim weave that I could see. Perhaps all the colours confused me. Bright colourful lights!!!!!!!!!!!
I measured this material in my calipers compressed, at .0235". It shot amazingly well in every gun I had at the time, expect for the heavy hunting loads in the .69 - That rifle with THOSE loads prefers 12 ounce denim I measure at .030". This is likely due to it's less than perfect bore (cross-reamer marks), although it does feel smooth these days. I do have a few yards of 14 ounce at .034" that shoots just as well as the .030", it's just a bit tighter, as you can imagine, especially with the .684" balls.
The reamer marks are still visible, but cannot be felt.