Selecting the right grit without taking off excessive amounts of wood Sandpaper doesn’t just smooth wood. Every grit leaves a certain type of scratch, and the size of those scratches is what you want the next level of grit to address. Coarse paper is meant to cut faster and remove more material; finer paper is supposed to refine the surface left by the coarser one.
The difference matters in furniture repair because aggressive sanding can round over sharp edges, eat up veneer, dull details and remove more of the surface than the job demands. A good way to see how grits change is to try it on some scrap wood first. Sand a patch with a coarse grit, another with a medium grit and another with a fine grit. Use the same amount of pressure and the same number of strokes for each. Then clean off the dust and view all three patches at an angle to see how they catch the light. The coarse one will have the deepest scratches. The fine one should be the most reflective. This exercise makes the grits easier to relate to than if you just memorized numbers.
Your starting grit should be based on the state of the surface rather than a standard sequence you use for any project. A badly damaged or peeling finish may need a lot of material removal, whereas a lightly scratched or bumpy surface might not. If the finish is good and you’re just prepping for another coat, going too coarse may be unnecessary. You’ll spend time removing the scratches you’ve made before you can put stain, paint, oil, wax or another clear finish on cleanly.
It’s easy to do too much with a coarse grit. The surface might feel smooth to the hand, but once you remove the dust or look at the surface at an angle, deep sanding marks may be evident. This effect is most noticeable along edges and corners because they wear away the fastest. Flat surfaces benefit from a sanding block, which tends to apply more even pressure, but delicate edges require a lighter touch. Be especially cautious on veneer, because the wood layer is sometimes very thin and easy to sand through.
When you move to a finer grit, don’t just polish until the surface feels silky. Each grit has a purpose: to cut down the scratches left by the previous grit without unnecessarily altering the shape of the surface. After a few strokes, stop and remove the dust. Look to see if the older, deeper scratches are still present. If they are, continue using that grit, rather than moving up to a finer one. Fine paper can make the surface feel smooth, but deeper scratches may still be underneath and will likely resurface after the stain or finish changes the way light reflects off the wood.
You’ll know you’re sanding better when you’re taking less material off and getting a more even surface. You should be able to see a uniform scratch pattern, the edges should stay sharp and you shouldn’t need many extra corrective passes later. Instead of viewing coarse paper as faster and fine paper as safer, think of each grit as a specific kind of cutting tool. Selecting the least aggressive grit that will solve the surface problem is usually the key to precision furniture repair.
