This archival heat set tissue is made from a fine yet strong long fibered Kozo tissue (RK1 from Paper Nao, Japan). It has an off white colour which blends well with older papers and has good clarity.  A very fine film of Texicryl heat activated adhesive has been bonded to one side of the tissue.

Safer alternative to damaging "sticky" repair tapes.
Training from a Conservator should be sought before using heat set tissue on collections.