Ring and Ball Testing to Determine an Adhesive’s Softening Point

Hot melt adhesives, such as those used in disposable hygiene products, are applied in a molten state and set as they cool. Apply at too low a temperature, and the adhesive may not bond well to the substrate. Apply at too high a temperature, and it may take too long to cool, damage the substrate, or bleed through.

Hot melt adhesives do not melt at a single temperature. The ring and ball test determines a single temperature, known as the softening point, within a hot melt adhesive’s softening zone. The softening zone is the range of temperatures across which the adhesive softens or solidifies.

How the ring and ball test works

A steel ball of specified weight is placed on a ring filled with the adhesive sample. It is then heated at a prescribed rate in a prescribed test liquid. At a certain temperature, the ball will fall through the ring.

This temperature, known as the adhesive’s softening point, is one of several necessary elements needed in determining the adhesive’s application temperature window and open time. Both are important considerations when choosing the right adhesive for a production line.

Bostik is able to emulate a disposable hygiene manufacturer’s production line conditions to make recommendations and help ensure our adhesives will perform as intended for its products. Our adhesive experts are also specially trained to provide professional and thorough audits of your line and products upon request. This may include recommendations for optimizing line performance and improved profitability.