Spent years buying random sandpaper. Finally figured out a system that works.
The Grits That Matter
80 – removing material. Old finish, shaping. Aggressive. Leaves deep scratches you’ll spend time removing.
120 – after power tools. Jointer marks, planer snipe. First step on rough lumber.
150 – general smoothing. Where I spend most of my time.
180 – pre-finish for paint. Good enough. Don’t go higher.
220 – pre-finish for stain or clear coat. Standard stopping point.
320+ – between finish coats. Rarely on bare wood.
Skip Grits, Cause Problems
Going 80 to 220 doesn’t save time. You just push the 80 scratches deeper. They show through finish.
Jump one grit at most. 80, 120, 150, 180, 220. Each step removes the previous scratches.
Types
Aluminum oxide is the standard. Works fine. What I use mostly.
Garnet cuts softer but burns out fast. Old school choice. Not worth seeking out.
Silicon carbide for wet sanding finishes. Grey stuff. Between coats.
Random Orbit vs Hand
Random orbit through 180. Hand sand with 220 in the direction of grain. This prevents swirl marks.
I skip hand sanding for paint grade work. Swirls don’t matter under primer.
Buying
Diablo or 3M. Store brand is hit or miss. Bad paper falls apart, clogs fast, wastes time.
Buy sheets for hand work. Discs for sanders. Rolls if you go through a lot of one grit.
