I always wash first if it's washable. That way there are no surprises later. Some interfacings can also be preshrunk or steamed. You need to check for care instructions.
I wash them--not so much because of the shrinking--but because of the fading. A beautiful project can be ruined the first time it's washed if the colors bleed into each other. I love applique too!
If it can b washed I would say yes. Things shrink. If it is something you would be afraid to wash then I think a good steam pressing would probably help. *
Great question, this never crossed my mind until I saw your question. H&*.
SUzette I always wash my materials before stitching because of shrinking.
I agree with Yvonne if there's a chance it might shrink you better do. good luck with the appliques.
Suzette. yes you should. I only wash the ones that I think might shrink.
I wash all fabrics with natural materials cause of the shrinkage and the color before I will do anything with them (sewing and stitching). It's anyoing when you work with different fabric and they shrink not all in the same way or one is loosing colors and ruins all the work. When some clothes are finished my kids woun't wait to wear them so it's better to wash the fabric before to get all staff out like things against clothes motts and others.
ansalu