I treat my fabrics exactly the way I believe the finished project will be treated- meaning- if I am making a wall hanging that will probably never be laundered I do not bother pre-washing (most of the time) if I am making a quilt or quilted item that will be laundered there is a very good chance I am pre-washing the fabrics involved- especially ones I am not sure about- better to pre-wash & see than to make a bed quilt- give it away- have the recipient launder it and find it ruined. when ever in doubt- pre-wash to be sure....whether it be hand dyes/batiks, metalics or other specialty fabrics, vintage fabrics- anything new I have not worked with before- I want to know how it is going to come out before all the work of putting it into a quilt