Young's Modern Sett Size?

[figheadair]

Collectively you've answered the OP insofar as if one keeps the same thread count then the heavier the weight the larger the sett: think tie vs carpet. Where it gets slightly more complicated is when there are slight but subtle changes to the threadcount. Yes, it is allowed .

Until the late 18th century there would not have been standardised threadcounts and even once these began to come in there was still room for variation. In Wilsons' 1819 Key Pattern Book they give several counts for some setts, particularly the military tartans, and these not only give different sett sizes but often have different proportions too. In other cases, for example the counts for their military plaids, they changed the count according to the quality (weight) of the cloth to maintain the sett size and so give uniformity of appearance which was a requirement of the military by then. So, Officers' plaids which were finer had a larger count than Sergeants' plaids which in turn had a higher count than Soldiers' plaids but all three resulted in an approximately 11.5 inch half sett..