You probably guessed it - my walk took place in warm water with a little soap and with the piece of sailcloth under my feet. Here are the results - first, the cloth straight off the loom:
and after having been washed once, gently,
which did not make too much of a difference, and finally after fulling by foot:
The comparison pictures are taken from the exact same spot (I stitched a marking angle with red thread into the cloth, you can just discern it in the upper right corner next to the frame thing). It's fascinating how the cloth changes by fulling, and it is not only the optics; it now feels somehow fuller and stronger yet with a soft, fluffy finish at the same time. It has shrunk a little, though not very much, and from my first rough counting it fits exactly in the approximate 5 to 4 threads per cm that it should.
So... whew. Second of three pieces of cloth done and finished, and just as it should be. Now it only needs to be cut into the pieces required by the museum and hemmed - nice work to do while sitting in the sunshine!