HA!- thought he said undeservedly - ha! Yeah - like Taylor said, SHARP arch punch over High Density Polyethylene (HDP in the US) (UHMW in Canada), or large ball bearing and a bearing race.
UHMW means Ultra-high Molecular Weight - same thing - high density poly. It is the material used for butcher's cutting boards as well as bearings for chain-guides in lumber mills.
The material that is coloured, cannot be used for butcher blocks- here. All scrap produced during the MFG process, is run back through again and the Canadian Government calls that 'used' and demands a die be introduced due to the possibility of that material, once hitting the floors, being contaminated - thus cannot be used for butcher blocks or cutting boards, but works splendidly for cutting patches or bed for running chains in a mill.
I picked up a couple black blocks, 1 1/2" thick X about 10" square for $10.00 each - one for my bro, of course. After cutting thousands of patches, still going strong.
Some cloth will lose thickness after washing (denim) (I run it through the wash cycle it twice) while others will gain a thou or two- like some of the ticking's I've used. Other cloth simply remains the same.
I suspect the material we called Railroad mattress ticking, that measured .0235" for me with one set of calipers, is actually a thin canvas, but a fairly closely knit one.
Measuring patches 101.
I have 3 sets of dial calipers - I have one set of Sterrit vernier calipers.
My Vernier calipers measure the same as one of my sets off dia, which the other 2 caliper measure thicker. It's all in how wide the jaws are, I assume. They ALL measure identically on a hard surface- no change there - but I get 3 different thicknesses when measuring cloth. My mic measures .001" thinner than my thinnest measuring calipers - WHICH- depending on WHAT cloth is being measured, can be up to .004" thinner than the calipers that measure the thickest.
Add technique into that, and it's hard to say what thickness ANYONE's patches are - use what works for you and record what YOUR tools say it measures.
I find 10 ounce denim to be quite consistent and actually shoots in EVERY rifle I've ever tried it in, with a ball that is .010" to .005" under bore size - OR larger - no matter what the rifling depth happens to be. For me, the deeper the rifling, the larger the ball. If it isn't compressing (by measurements) in the bottom of the grooves, it's too thin -- for me.
Ox Yoke .018" in the plastic bag - for me, mics .0145" to .015" - it is too thin for my use, in any of my rifles.