Block-Weave Profile Drafts
I'm working my way through your Block Weaves video, and I have a couple of questions. (I'm only through disc one, so if the answer is on disc 2, just tell me to finish watching!) Are units always square in block-weave profile drafts? For example, if the threading for a unit calls for 4 warp threads, does the treadling always call for 4 weft picks? If 6 warp threads, 6 picks?
Are there only two unit weaves (damask and 3-end block weave) that call for an odd number of warp threads and will they take a corresponding odd number of weft picks? And, finally, are all block-weave profile drafts composed of an odd number of blocks both across and down?
Just in case these questions are not addressed specifically in the video, here are answers!
Units are not always "square" if by that you mean that they all have the same number of warp threads as weft threads. Usually, the word "square" is a design principle. That is, visually in a cloth, the width of the threads weaving pattern in a single block should be the same as the height. If you weave summer and winter so that the plain-weave ground cloth is a true 50/50 weave (number of warp threads per inch equal to number of weft threads per inch in the ground cloth), you'd need twice as many weft threads as warp threads for one "unit" since there would therefore have to be 4 tabby weft threads and 4 pattern weft threads but only 4 warp threads. And, to get the 4 tabby picks, you'd need to weave two full structural treadling units. Similar issues are involved for all weaves with supplementary pattern threads, in either warp or weft. Often, to make the design look square in a cloth the actual number of picks is determined only by what looks square.
In many other weaves (50/50 weave structures that have the same number of picks per inch as ends per inch), though, the number of threads that produce a "square" in the weft is usually the same as in the warp (turned twill, doubleweave, damask, lace weaves, for example).
In warp rep and weft rep weaves, though, the numbers of weft vs warp threads to produce a "square" are very different.
Some damask threadings (5-end and 7-end) have odd numbers of ends though not all…and yes, you are right, 3-end block weaves have an odd number of warp threads though not an odd number of weft threads. The number of threads in a unit is not really odd or even by any intent, just by how the structure happens to work.
Block-weave profile drafts can have even numbers of blocks. It's only that often, when a design is symmetrical, there is a turning block that causes an odd total number, the same way as point twill threadings often have odd numbers when you add the last thread to balance. 1-2-3-4-3-2-1.
These are good questions, and if the answers aren't clear, I hope they are by the time you finish disc two!