Method of and means for providing an effective thermoplastic adhesive connection or seal using thermochrome dye

A method of making adhesive connections or seals using a thermoplastic adhesive where the thermoplastic adhesive remains at or above the minimum temperature required for satisfactory moistening the materials to be glued or sealed and indicating when the temperature of the thermoplastic material falls below the minimum temperature required for satisfactory moistening comprising the steps of using a solid thermoplastic adhesive containing at least one thermochrome dye showing a color change in the temperature range between the minimum temperature necessary for satisfactory moistening of the materials to be glued or sealed by the thermoplastic adhesive and a temperature approximately 20.degree. above the minimum temperature at which a satisfactory moistening occurs, and heating the solid thermoplastic adhesive into a molten state where the molten thermoplastic is sufficiently viscous and is heated to a temperature at least approximately 20.degree. above the minimum temperature necessary for satisfactory moistening and noting any color change in the thermoplastic adhesive indicating that the thermoplastic adhesive is approaching the minimum temperature necessary for satisfactory moistening.