A five-year study by FOGRA of complaints regarding bookbinding showed more than half dealing with hot-metal adhesives. About 60% of this group concerned materials and 40% processing. The processing problems discussed concern the back of the book (especially where hot-melts are used with coated papers), the optimal processing temperature in relation to the open time (between glue application and combining the book tablet and the cover paper), the thickness of the hot-melt film with regard to open time, gluing the cover, and difficulties in adhesion with printed surfaces on the inside of the cover. Problems arising from the materials include poor adhesion of coated papers, sheets printed into the back margin, chemical reactions between hot-melt and cover board, and binding of rotary offset papers. The testing of thermoplastically bound books is also discussed, viz., determining the working temperature of hot-melts, measuring the amount of adhesive applied (coating thickness), pull tests and flex tests, and the use of test bindings. -- AATA