What is a Block?
Block is a term that describes any structure forming floats organized in squares or rectangles. A color gamp has blocks of color, a twill gamp has blocks of twills woven with different treadling; and, given enough shafts, any structure can be organized in blocks.
Traditionally, the term has been used for structure that form organized floats inherently. Basket weave and the group weaves – huck and huck lace, Spot Bronson and lace, Swedish lace and M’s & O’s – form blocks as an integral part of the cloth. The three weaves below – overshot, crackle and summer & winter – form blocks using an additional pattern weft; their similarities make them confusing, so here is a comparison of the three.
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Overshot, tromp as writ, also called star fashion:
Crackle traditional, each block a different color:
Summer & winter, treadled as singles:
Each one of these structures offers many more options, but I hope these comparisons help you differentiate between them.