OK, my desire to explore kicked in and I went to the source of all knowledge,
the internet. I use a basting product "SpraynBond" available at JoAnn's, Amazon, Walmart etc., and it clearly says that it washes out of fabric. I also found an article about two spray basting products and using school glue.
https://growyourownclothes.com/2015/09/07/does-temporary-basting-spray-wash-out/