A heat seal adhesive developed by Gustav A. Berger of New York which is widely used for the lining of oil paintings, heat seal facings and the making of laminates with fibreglass etc. BEVA 371 is non-aqueous and is dissolved in non-polar petroleum fractions known to be harmless to most paint films. It is applied cold. It causes no contractions, expansion or softening of the materials to which it is applied making its application possible on even the most delicate surfaces. Shrinking and distortion is minimal. Heat sealing can be done days or weeks after application. Since BEVA 371 is completly dry at room temperature, it is easy to reassemble fragments and secure them in the right position with a tacking iron. BEVA 371 was specially formulated to have an activation temperature of 65-70° which was considered best for the themoplastic treatment of old, distorted paint films and cellulose tissues. At this temperature, old paint films usually become quite soft and can be bent to be brought back into intimate contact with the supporting fabric. At 65°C BEVA 371 becomes as tacky as a contact adhesive at room temperature. A firm bond can be achieved almost instantly and with minimal pressure so that even the most delicate textures do not suffer. BEVA 371 does not have to be adhered and is viscous at activation temperature, the smallest fragments can be put together at leisure without danger of soiling them. BEVA 371 is reversible and errors can be easily corrected even after heat sealing. It is easy to remove and can be remelted whenever needed. BEVA 371 has only limited solubility at room temperature though it absorbs solvents and forms gels which no longer adhere to the bonded materials. These gels permit removal without staining. A large proportion of low molecular substances with high melting points have been incorporated in the formulation, they make it fairly rigid and free from cold flow at room temperature. These qualities enable BEVA 371 to keep the painting straight after lining and to provide a film bond for facings. The large proportion of low molecular substances in the formulation enables it to maintain low viscosity when used hot or dissolved in harmless petroleum fractions. This makes impregnation and consolidation of paint layers and canvas possible at every stage of the lining process and afterwards if needed. BEVA 371 can be applied by brush, paint roller or spray without impregnation of solvents. It is possible to lower the heat sealing temperature by using BEVA 371 films half dry or moistened with sprayed on petroleum fractions.