Out, danged spot!!
"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!