Introduction:
I don’t think I can define blocks with one or two sentences. I’d love it if someone would do that. I will replace the bad definition I have in one of my books
I think of weaving blocks like having more than one loom side by side. That way you could weave different things next to each other on a cloth. For example, I would weave twill for some of my warp width and basket weave at the same time on another part of the cloth. Or, say I could have a twill cloth with borders in basket weave. A secret: each loom will become a block, read below.
Let’s say you want to weave a design like the one in the illustration. One weave is for the main part of the cloth, and a different weave is for a vertical stripe.
The threading draft would look like the illustration. See that the “first loom” is used for the background and uses the first four shafts. Most of the warp would be threaded on shafts 1,2,3,4 because most of the warp is the background. It’s only in the area where the stripe is to be that the “second loom” is needed—and it’s only in that area where the threads are threaded on 5,6,7,8.
Don’t let the place where the stripe and background meet and the threading is 1,2,3,4,5,6,7,8 confuse you. It’s really 1,2,3,4 and then 5,6,7,8 where the second loom begins.
How do you get both weaves? It happens with tie tie-up draft. Look at the illustration. First, the tie-up is given for “loom 1”, a balanced 2/2/ twill. See that the combinations of shafts to be lifted are; 1,2; 2,3; 3,4; 4,1. The tie up for “loom 2” is given in the second part of the illustration, for a warp-faced, 3/1 twill. (That means 3 shafts up and one down for a 3/1 twill (warp faced twill). Those combinations are 5,6,7; 6,7,8; 5.7.8; 5,6,8.
To make both twills weave at the same time, combine the two looms’ tie-ups as shown in the third part of the illustration.
The treadling draft would show the first X under the combination 1,2,5,6,7. The second X is under the combination: 2,3,6,7,8. Since there are 4 combinations used, four treadles will be needed.
Again, working in the tie-up draft try a variation: “loom 1” a weft faced twill (1 shaft up and 3 shafts down: (lift 1,2,3,40 and keep “loom2” weaving the same as before—warp faced twill with 3 shafts lifted and one down. That is: 5,6,7; 6,7,8; 7,8,5; 8,6,5.
Notice in the illustration I’ve indicated a dotted line in the final tie-up to separate the looms.
Here is the complete tie-up now, putting the lift sequence for the “second loom” on top of the tie-up for the “first loom”, above the dotted line. I often write 1,2,3 and 4 very lightly instead of 5,6,7,8 at first. Then I write the real shaft numbers of 5,6,7,8 over the temporary numbers, because it’s easier for me to think of four shafts and two looms.
Remember that each treadle will lift shafts from both “looms”, forming one shed. Since there are four sheds for this design, only four treadles are needed.
Finally, What are Blocks?
We can give the different “things” we are weaving a proper name. They are called blocks. We name the blocks A or B or C or D instead of loom 1 or loom 2 or loom 3, etc. Look at the illustration above. There are two blocks or two different “looms” or groups of threads that act together as a group as though on separate looms. They can weave different things, but they will always be in the same location (vertical column )in the threading. Can you see that there are only two threading blocks or that all the threads on “loom 1” are in the same vertical column so they would be threaded on their own set of shafts, and all the remaining threads are acting act alike so they would be on their own separate “loom”?
What if you don’t have blocks?
Then all the threads across the warp would work together as one loom from selvedge to selvedge.
Can you weave with blocks if you have only 4 shafts? YES!!
You can divide a four-shaft loom into “two looms”. In fact, there are many weaves that have blocks that only need 4 shafts. Some can weave as many as 4 blocks with only 4 shafts.
Here is a chart which shows the number of shafts you must have for the number of blocks you can have.