Mirror -slide is simply that some people, once they have reduced the residue/s on the lace to a gel /gooey consistency using Alcohol such as ``Pure``, then slide the lace system across a glass surface, such as a mirror....this simply transfers the mess from the lace to the glass....obviously the glass then has to be cleaned off !
Many people opt to use pages from a magazine, bubble-wrap [as comes in padded envelopes ] or microfiber cloths....these can be discarded after use.