Among a selection of many colors for Coron Sashiko Thread, the two colors of Original White Bright White are the most popular colors. We, as a group of Sashiko artists, also use a lot of both original white (#10 / unbleached white / ecru ) and bright white (#12 / bleached white). The white color thread and Indigo Dyed Fabric is the most popular and traditional Sashiko combination. When you research on Sashiko, you would see the dark blue fabric with white Sashiko stitching on.
Which is the better choice? | Original White Bright White
Both color, #10 and #12 are great for Sashiko stitching: the same quality cotton thread with a twisting for the Sashiko purpose. The #10 has the original color of cotton, which is a bit more creamy ecru color. The #12 has the bleached color, so it is bright white as you would imagine for bleached white. The comparison of light color may be a good example. #10 is more like the warm white, and #12 is more like the cold white. I personally like the #10 ecru color, but at the same time, I enclosed the #12 color on the workshop materials so participants can ask questions about color transferring from fabric to thread.
Here, I took a photo of the comparison on Indigo Dye Fabric.
In the photo, without stitching, the #12 looks much more white like. #12 is bleached so it looks really white, but after making stitches on the Indigo Fabric, both #10 and #12 looks “white.” I will make a sample fabric later on.
Which thread did the Japanese use in their tradition?
I am still in the process of researching, but some people in the northern region had a shame of using the white thread because it means a lack of effort of dyeing the thread with natural dyes (Natural Dye Sashiko Thread.) At the same time, some people who lived close to the castle town thought of using the original white to enjoy the pattern and its Indigo and white contrast. The Japanese had a technique to bleach the cotton thread by using nature such as snow, rain, and sunlight.
As the answer to the question, I would reply that the Japanese used both white colors as well as the Natural Dye Thread.
Each Sashiko project requires the appropriate thread color, I believe. I hope you can find the best matching color to your project.