It should tell you in the instructions. I just finished one with grid lines and all the stamped bits disappeared as soon as I gave it a gentle wash. My instructions said to make sure you don't get the aida wet until you have finished. i'm very happy with the results.
Enjoy your cross stitching 
WORD PAIRS -APRIL 2026 (Old thread full )
Something for new Mum ........
Hundreds of illegal migrants to be put in existing military barracks


