Sorry if I wasn't clear. A 4 yard kilt is going to be cooler than an 8 yard kilt, period. It doesn't really matter weather is it box or knife pleated. I don't think the style of pleating has any bearing on the temperature whatsoever.
The only exceptions that I could think of is maybe if you got a 4 yard kilt in a super-heacy 22 oz regimental weight, and an 8 yard kilt from a 10 oz light weight, the 4 yarder would actually be warmer. But as long as you are comparing like weights, the 5 yarder will always be the cooler of the two, because it contains less cloth.
But I find my 16 oz 4 yard kilts comfortable year round. I live in the usually moderate climate of NC, though.
I find that it is the kilt hose that determine if I am cool or warm. I have some woolen, over the knee hiking socks that keep me nice and toasty in the coldest spells.
Ron, I'm pretty sure the X Marks tartan was 15 oz, but the Fraser & Kirkbright mill uses a fine merino wool, so even though is it a heavy weight, the fabric feels more like what you might expect a medium weight cloth to feel like.
Aye,
Matt
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