The answer is "It can be any kind of thread." but using the specific thread designed for Sashiko purpose will result in much better stitches. Our sashiko thread is exclusively designed for Sashiko purpose. Six of thin embroidery threads are twisted with special technique. It will give you the great result.
Sashiko requires a lot of time to invest. We would like to have the best result for the time we invest. Please enjoy one of the best quality Sashiko threads in the market.
We, as "Sashi.Co", use this great Sashiko thread to produce our Sashiko art pieces. The price may seem a bit expensive for a skein of thread. Please be advised that this is 145 meter skein. One skein should be good for several Sashiko projects. We believe the price is reasonable in comparison of length, to other Sashiko threads from different manufactures.