Most epoxy systems will shrink in a range of 1-5% in volume once fully cured. You will find that in most applications, this shrinkage is virtually undetectable. Where it can be noticed is when epoxy is used to fill voids such as large knots and cracks in wood slabs. The best way to minimize the shrinkage is to slightly overfill these voids. Additionally, allow the overfilled void to fully cure (4-6 days) before block sanding flush with the substrate.