This paper presents the results of tests on adhesives that are used in the thread-by-thread tear mending of canvas paintings. Single-linen threads were joined using various natural and synthetic adhesives, and the ultimate tensile strength of these lap joints was tested. In the first series of tests, a mixture of sturgeon glue and natural wheat starch paste proved to be one of the best performers. This mixture offers a high tensile load capacity as well as other positive properties, e.g. neutral pH, reversibility in warm water, good workability, and positive optical appearance (it was nearly invisible). A further series of tests on wheat starch / sturgeon glue mixtures indicated that some industrially manipulated starch products (precooked and swellable in cold water) are an appropriate alternative to the commonly used natural wheat starch. Additional advantages of these precooked products are their quicker preparation and a more consistent paste quality. Some pH-neutral dispersions, based on ethylene vinyl acetate copolymers, also provided promising test results. Dried films produced from these are swellable, even in cold water. Finally, the paper reports on materials for the mending of torn synthetic threads, in this case Polyamide PA 6. The focus of this particular series of tests was the influence of the age of the thread and its sensitivity to light on the choice of adhesive.