Designed and manufactured by Ray-Ran, the Unrestrained Linear Thermal Film Shrinkage apparatus or more commonly referred to as the liquid immersion method, is used to determine the thermal shrinkage of plastic film & sheeting.

As a result of manufacturing processes, internal stresses may be locked into a film or sheet which can be released by heating which causes shrinkage of the material. The amount of shrinkage which takes place is dependent on the temperature during the test. The results are plotted on a graph showing percentage shrinkage against temperature.