I have several examples of outdoor gear to look at and a spool of new, labeled T67 size Coats "outdoor UV resistant" thread as a benchmark for thread size and appearance. That Coats thread is multi-ply, but it is very polished --bonded? -- and springy and potentially tangly. No fuzzies whatever.
A few comparisons:
The stitching on a Clark hammock and a Clark tarp both look much heavier than the on-spool T67 (/V69). The stitching on a Warbonnet Blackbird also looks heavier, but not as heavy as the stitching on the Clark hammock and tarp.
The stitching on all hems and seams on a Gossamer Gear pack and on an Arkel (heavy Cordura nylon, nothing UL about it) pack / pannier also look much heavier than the new T67 thread, about what I see on the Clark gear.
Questions: Are those heavier threads V92 weight?
Could they be even heavier, ie V138
Does threading usually look heavier and bulkier after it has been through a commercial sewing machine?
Could I be seeing polyester-cotton blends in some of the other threads?
There are literally thousands of weights of thread, but the commonly available heavier ones 92 and 137 very well could be what you are seeing. Many factories in china don't buy their thread from supply stores so it's likely on a large production item the thread was made specifically for the item with function/asthetics in mind. So on those types the sky really is the limit as far as what kind of thread they are using. That being said you could call up a supply shop and ask for match samples of their 92 and 137 and compare. I haven't personally seen a heavier thread poly mix but it certainly can/does happen.
In my opinion machine has little to do with bulkiness of the thread on a finished garment, if the machine can handle it of course. The appearance of thread after stitching can be changed by machine settings (take up lever travel, needle tension, bobbin tension, hook timing) and many production books give ins and outs to get the look you are striving for.
Thanks for the insights and recognizing that appearance matters. Machines I have access to will handle a 19 needle.
I know that thread can be any weight a customer will pay for. (You and) I just listed a few benchmark ones that come up from the major makers with web presence (not inc Alibaba), benchmarks, maybe, because there is a US Gov spec at those levels, so there is lots of thread produced for the enormous appetite of the automotive and other upholstery industries.
I hope someone else who DIY's will look at their stocks of thread, and then at retail-made gear to offer some opinions of what they see.
This is just for DIY. And on fiber blends (and nylon): It was only from looking at catalogs that I saw that serious players offered them for outdoor use, no matter dogma about polyester for UV resistance.
I think that the rationale behind poly thread on nylon tarps is a little funny for most DIY because in all reality the thread used in the machine is so much larger than the individual threads in the weave of fabric that if UV is going to be the sole killer it will destroy the fabric first. The real problem with nylon on DIY comes from home machine needle availability. I use a needle with a larger scarf for nylon thread and these needles are readily available for my machines, but the stores like Hancock/joanns seem to either not have access to them or don't deem it worthwhile to carry nylon scarf needles.
I wouldn't recommend sewing anything above 67 with a size 19 needle. I would reccomend a 22 for 97. I do have both 137 and 92 in my shop, I'll go take some compare pics here shortly.
Having repaired a few arkel panniers I can say that the 137 bonded poly thread I used was larger than the factory thread but the 92 was noticeably smaller. I have not personally seen the stitching on a Clark, and haven't noticed the thread on a WB. I also noticed that many companies lately are using right twist thread to give a different look on visible stitching (msr, north face, marmot) and use regular core bond internally. I don't know if this has to do with the type of machine used or garment performance but it was interesting to me.