5.2 This test method measures weight loss. It can be used in combination with a knowledge of sealant density to estimate shrinkage. In addition, when compared to sealant theoretical weight solids, it provides an estimate of the extent to which functional sealant components can be volatilized when exposed to high service temperatures. Substantial losses of this type may help predict early failures in durability. Also, development of cracks or chalking, or both, lessens sealant service life. However, a sealant that develops no cracks or chalking, or low weight loss in this test method, does not necessarily assure good durability.