To create a new pattern heddle storage system, the weaver begins with her loom warped with the warp threads passing through a pair of fixed heddles for the ground weave, and then behind that, each warp end passing through it’s own long vertical string heddle.

No horizontal strings are in place in the storage system yet: 

She then begins to weave the pattern of her choice by using a thin sword to pick up the warp ends she wishes to pass her supplementary pattern weft under:

After picking up the warp ends for that pattern row, she turns the narrow sword on end to open the pattern shed, then inserts her large sword in that shed, but between the fixed heddles and her new pattern storage heddles, and turns it on its edge:

Now she can remove the narrow sword and use it to coax the vertical heddle strings to separate into two groups: the ones that are raised she brings forward, and the remainder she pushes away from her so a space opens up between them. This includes gently pushing the vertical heddles forward so that the raised ones stay forward and the others fall back, as well as using her narrow sword to comb the raised heddles toward her along the still-raised warp ends:

This is a fiddly process, and I watched this weaver start over and go through the delicate process again until she successfully separated the vertical heddle strings:

Finally, a clear separation is made between the two groups of vertical string heddles:

Only then could she insert a horizontal string loop between the two groups of vertical string heddles and drop it into storage on the yellow frame below the warp:

Lastly, she inserts the pattern yarns for that row into her weaving. Here is a video of that process, but a different weaver on another warp:

In the lower left of the image below, you can see that she has a few horizontal strings stored underneath the loom (around the yellow tubes), and for each one of those strings, she went through the whole process described above!

The effort is worth it though, because once she has her pattern stored, it will save her an enormous amount of time to not have to pick each row by hand, and it can be used for future weavings and by other weavers.

Here’s a stored pattern that has been moved up to the frame above the warp:

These images were taken at Phaeng Mai Gallery in Vientiane and at Ock Pop Tok in Luang Prabang.

See more about Lao-Tai pattern heddles at: Luang Prabang: Lao-Tai pattern heddles

See more about Lao techniques

See more about Lao Textiles

For details of how the vertical part of the pattern heddles are constructed, see Deb McClintock’s description on Looms of Southeast Asia. Scroll down to reach the heading The Khao Nyai is Made.