I live in Northern California. I use mineral oil on the blades, but I rarely put anything on the handles, and have not had any noticeable shrinkage, beyond what sometimes comes from Nevada. I've sanded a few handles to bring out a high polish (2000 grit), and sometimes I apply tung oil after sanding, but most of my wood and horn handles are left as they arrive from HI. I've been collecting HI knives since 2011 and it's been so far, so good as far as handle shrinkage is concerned.