See my previous post for the background to the test results below.
When all threads were applied to the three fabrics, I had 63 separate samples.
The Kreinik silk (light blue) and Trebizond silk (gold) were the hardest to work with. I had to use incredibly short lengths to keep the twist, which, on a full size piece, means more stopping and starting. I did not wax the threads, but I now know probably should have tried that (thank you Crystal).
The Kreinik silk was very delicate, but also wonderfully soft. This was my least favorite in comparison to the others, but some of that was because I had to change a lot of my stitching habits quickly to keep from destroying the thread! It worked best overall on the cotton canvas, particularly the brick stitch. It also produced a nice bit of long-arm cross stitch on the 32-count, but some of the trick was to loosen the twist a bit so that it created a more subtle braid.
The Trebizond silk was much better at keeping the twist on the worked stitches, but about 2" at the end had unraveled as I stitched. It also did well on the canvas, but seemed to be best suited to the stem stitch across all three fabrics. A full-sized piece with this shiny thread would be quite beautiful, and I doubt a lack of metallic threads would even be noticed!
The navy blue Grandeur silk was the most like the pearl cotton in terms of the working process, but I still needed to use shorter pieces than I would with cotton to keep it smooth. It held the twist with no problem, but it was just as sensitive to the act if being drawn through the fabric as the Kreinik and Trebizond silks. Overall, I loved using this thread, and I found it to be the best choice of the bunch for making the transition from cotton to silk. It worked well for all stitches on all three fabrics, but how it looked in long-arm cross stitch was especially nice, particularly on the 32-count.
The Impressions 50/50 (gray) is to die for in texture. It is smooth and soft- the best qualities of silk and wool respectively. I had high hopes for it, since it is also very similar to the pearl cotton. The gauge is smaller, however- more like a #8 pearl cotton than #5. Similar to the Grandeur, it held the twist well. Its smaller gauge made it seem finer than the others, particularly on all three samples of split stitch. It did well on the canvas, but worked brick stitch better than the others on the 32-count (once again owing to its size).
When I got to the Bella Lusso (light pink) wool, I did go through a learning process about using crewel wool. The thread is incredibly soft and fluffy to hold, and the results were unbelievably delicate in look. I was concerned that the wool would fuzz up as I worked it, but that wasn't a problem. The best sample was the double strand split stitch on the 28-count linen, but the long-arm cross stitch done with a single strand on a 3x3 grid (instead of 4x4 like the others) was also nice on all three fabrics. The clean look of the brick stitch with a double strand on the canvas was a nice surprise.
The Medici wool (rose pink) was slightly rougher in feel than the Bella Lusso, and could be described as hairy. Since I'd figured out that a double strand was the better way to use the crewel wool, I did not bother trying any single strand samples. It worked well for all the samples, but had a more pronounced hairiness even after being used. The long-arm cross stitch stood out on all three panels.
The other result of the test showed that the stiffer ground of the cotton canvas performed well for all thread samples and all stitch types. While this is somewhat disappointing, since it is a modern ground material, it's also nice to know that my stash of it won't go to waste! It would make a very good ground for a large bag. However, since the point of all this was to locate a thread and ground combination as my first foray into more authentic materials, I'll save the canvas for a future project. I included it basically because I had it, and I didn't know if it would be good for anything.
After several minutes of staring at each sample, I finally decided that the Rainbow Gallery Grandeur Silk in long-arm cross stitch on the 32-count ground was the best of the bunch. It was followed quite closely by the DMC Medici wool in long-arm cross stitch on the 28-count linen.
So I need to now take some time to research long-arm cross stitch to discover the possibilities for something appropriately 15th century. I have already come across a few, but if you have any links you can share in the comments, I'd love to see what you've found.