How to Control Where Partial Tapestry Rows Stop on a Rotating Heddle Bar

A shed is the opening between raised and lowered warp threads. On a simple rotating heddle bar, turning one way raises one set of threads; turning the other way raises the alternate set. Mirrix describes this mechanism in its Shed Systems for Tapestry Weaving.

The practical consequence is that an opening across the loom does not require a weft to cross the entire width. You can withdraw a needle or small weft bundle partway across, leaving the remaining warp untouched by that color. Its turning warp establishes the edge of the woven area.

For clarity, this article calls one journey through a shed a pick. An outward pick followed by a return pick in the opposite shed forms a two-pick sequence. Counting these separately makes endpoint instructions easier to follow.

Start with a correctly warped loom and a short woven foundation. Check that alternating the bar produces two clear, opposite sheds. Designer Maria Sigma emphasizes even warp tension and explains the rotating bar’s role in separating alternating threads in Warping A Frame Loom (Heddle Bar).

Choose the boundary in terms of actual warp threads. “Stop near the middle” is difficult to repeat; “turn around warp 8, counted from the left” gives you a specific thread to find. Count the working warp ends at the weaving surface, following each one down to the woven edge if the open shed makes their positions confusing.

For an independent color block, identify its first and last warp. For a boundary between two blocks, identify the gap between their edge warps. These are related but different references: a block covering warps 1–8 ends around warp 8, while its boundary with a block covering warps 9–16 lies between warps 8 and 9.

A paper design guide behind the warp can help you follow a planned outline. Such a guide is commonly called a cartoon; Claudia Chase’s tutorial published by Gist Yarn includes this approach in Tapestry Weaving on a Mirrix Loom. Keep your counted turning warp as the immediate reference when placing each pick.

The following exercise uses an illustrative 16-warp area, with the left-hand color assigned to warps 1–8. The numbers are teaching coordinates, not required loom settings. Use the warp spacing your bar and loom are designed to accommodate.

1. Find warp 8. Trace it to the woven foundation and identify the gap immediately after it, between warps 8 and 9.
2. Open the first shed. Pass your weft through the opening from the left, covering only warps 1–8.
3. Exit at the chosen gap. Bring the entire needle or weft bundle out between warps 8 and 9. Check that it has not accidentally passed around warp 9.
4. Allow enough weft. Leave a shallow curve in the inserted yarn rather than pulling it straight and taut.
5. Change to the opposite shed. Return toward the left through warps 8–1. The reversal takes the yarn around warp 8.
6. Settle and inspect the sequence. Confirm the turn surrounds warp 8, the warp spacing remains even, and the two picks alternate over and under the same threads.

The structural check matters more than the direction in which your particular bar turns. In plain weave, each successive pick reverses the previous pick’s over-and-under relationship. The Art Institute of Chicago illustrates this in Weaving Structures. If the return follows exactly the same path as the outward pick, check the shed before continuing.

Repeat the exercise at the same turning warp to practice a vertical edge. Keep the yarn available for the next sequence; a partial row is a change of direction within the weaving, so you do not need to cut the weft at every turn.

For a simple two-color sample, assign the second color to warps 9–16. In one shed, weave the left color toward the boundary from the left and the right color toward the boundary from the right. Change sheds, then take both colors back toward their respective outer edges.

This arrangement is called meet and separate: neighboring wefts travel in opposite directions within the same shed. Chase’s Gist Yarn tutorial explains that maintaining this relationship helps colors move into neighboring areas while preserving the correct shed.

For this exercise, work both colors in the current shed before rotating the bar. That gives you a straightforward rhythm: both move inward, change shed, both move outward. It also makes it easier to see whether either color has missed a pick.

Do not move a boundary merely because a warp appears uncovered after one pick. Rebecca Mezoff explains that a thread between approaching colors may be covered in the following shed. She also recommends completing two-pick sequences before deciding that a color cannot move where intended. See Four things a tapestry weaver needs to remember.

Choose the join before repeating a boundary upward. Separate turning warps, a shared turning warp, and linked wefts produce different connections between color areas.

Boundary method	Where the wefts turn	What to expect
Slit tapestry	Each color turns around its own adjacent edge warp	The areas remain separate along the boundary
Dovetailing	Neighboring colors turn around a common warp	The shared warp connects the areas
Interlocking	Neighboring wefts link with one another between warps	The wefts connect across the boundary

The Art Institute’s Weaving Structures explains these distinctions and why repeatedly meeting without dovetailing or interlocking creates a slit. Thus, two colors can stop exactly where intended and still leave an opening: endpoint accuracy alone does not create a connection.

For the counted exercise, keeping one color on warps 1–8 and the other on 9–16 demonstrates a slit boundary. If you want a connected boundary, plan a joining method explicitly rather than pulling the two independent edges tightly together.

Once a repeated turn is clear, change the turning warp according to a written sequence. The following is an illustrative plan for widening the left block. Complete each two-pick sequence before moving to the next entry.

Two-pick sequence	Left block’s turning warp	Right block’s first warp for a slit boundary
1	8	9
2	8	9
3	9	10
4	9	10
5	10	11

This plan makes the intended change inspectable: hold a boundary for two sequences, then move it one warp to the right. Both colors must follow the revised allocation. Otherwise, an unintended overlap or unfilled area can appear.

Treat the table as a sampling exercise, not a prediction of the finished angle. It specifies horizontal movement in warp threads, while the vertical distance depends on the actual height of your packed sequences. Compare the woven steps with your design guide as you work. Mezoff’s advice to finish the two-pick sequence is especially useful before changing the width.

Check the thread path first, then the amount of yarn, then the working space. This order separates a misplaced turn from a correctly placed turn distorted by tension.

• The color extends one warp too far: Trace the outermost turn. If it surrounds the next warp, undo that sequence and exit through the earlier gap.
• The return retraces the outward pick: Check that the bar opened the opposite shed and that no thread was missed during insertion.
• One warp appears uncovered: Inspect again after completing the next pick before adding an extra wrap.
• An opening grows between colors: Check whether you are making independent slit edges when you intended a connected join.

If the turning warp bends toward the color block, examine the weft allowance. Mirrix explains that weft needs extra length to travel around the warp after the shed changes. Its Prevent Pulling-In guide recommends laying the weft in curves or bubbles and keeping edge turns snug without drawing the warp inward. Apply that same check to an interior turning edge.

If alternating ridges develop, check whether both picks receive comparable amounts of weft. Mezoff also identifies weaving too close to the shedding bar as a contributor to surface irregularity in The surface of your tapestry: do those bumps matter?. Maintain adequate working space using the adjustments available on your loom.

Before extending a shape upward, weave several sequences at one counted endpoint. Inspect the turn, complete the return, and check the neighboring color. Once that small boundary behaves consistently, use a written turning-warp sequence to make each change of width deliberate.

• Maria Sigma, Warping A Frame Loom (Heddle Bar).
• Mirrix Looms, Shed Systems for Tapestry Weaving.
• Gist Yarn, Tapestry Weaving on a Mirrix Loom with Claudia Chase.
• Art Institute of Chicago, Weaving Structures.
• Rebecca Mezoff, Four things a tapestry weaver needs to remember.
• Mirrix Looms, Prevent Pulling-In.
• Rebecca Mezoff, The surface of your tapestry: do those bumps matter?.