"Um, do these pattern lines wash out?" It always breaks my heart when some super excited stitcher writes in to say "I applied the pattern in the wrong place / I messed it up / I ironed it onto my grandma's heirloom linens -can I wash it out? And...er...no, I didn't read the instructions first. I was just SO EXCITED TO GET STARTED!!!" I like that part, but don't like the "I messed it up in the first go" part at all. It is my responsibility to tell you: the patterns won't wash out. Or...will they?
Because I can't guarantee that the pattern ink will wash out completely, I err on the side of caution and tell you no! They won't wash out. Don't assume they will! Test first! Measure twice and cut once! Or, something like that...But wait! I may have an answer for you. For a few years now, people have been letting me know that they have had luck removing ghost-lines and unwanted transfer lines with a Tide To-Go Stain Pen. I haven't tried it myself, but field reports are numerous. Also...
Sublime Stitching friend Saskia says she found the way to get them completely and totally out:
Spray with Zout
let is sit for a while,
then use Oxyclean
Let me know if this works for you!