Vinegar and water would help to prevent crocking or dye bleed. You can block using plain water. This said, if the yarn used is a man-made fiber, you won't get the block to hold. Acrylics don't block out.songofjoy said:I need to block the corners of a knitted afghan as they seem to pull a little. Did I hear someone used vinegar water to do the blocking? Would love to hear from you out there in Knit/Crochet Land!!!