Every PU system will shrink during crosslinking. PU systems cure with an increasing core temperature. This means that heat is released during crosslinking. Crosslinking sections cooling down lead to a volume shrinkage. The extent of volume loss is influenced by several factors:

1. The shrinkage depends on the contour and wall thickness of the parts. The data sheet tells you shrinkage values which were measured at a specified geometry in the lab and are only to be taken as an orientation value. The shrinkage can vary depending on the part geometry.

2. Fillers: Unfilled systems have higher shrinkage values than filled systems. By adding filler the shrinkage can be reduced. Please note that filler also affects the mechanical values.