Undulating Twills

Marcy Petrini


On last week blog I showed a Christmas fabric with an undulating twill. The question came up: what is an undulating twill?

I like to think of an undulating twill as the result of stretching any twill. And there are many different ways to accomplish this stretching. Let’s take for example a straight twill: 1, 2, 3, 4, repeat. We could stretch it regularly:

This second, doubled, repeat changes the slope of the twill. We can also stretch the straight will irregularly:

This irregular repeat causes the undulating slope to be more pronounced.

My favorite way to undulating a twill is to do it in steps; I used this method for the Christmas fabric woven with a pointed undulating twill, shown here with its drawdown. The treadling is also undulating, but it is possible to use a number of treadlings, including straight and pointed twill.

Sett must be considered carefully. For example, look at the point where we treadle 3 & 4: the float is over 6 threads. At a sett of 12 ends per inch, the float would be ½”, likely too long for most useful fabrics. At a sett of 48, the float would be only ”. In the past I have used a different sett for different parts of the fabric, but that tends to diminish the undulation, defeating the purpose of the structure.


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