- PLANS & PROJECTS
- Hand Tool Skills
- Box Joints
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- Pocket-hole Joinery
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- Making Furniture
- Assembly & Glue-Up
- Fixing Mistakes
- Blades, Bits & Accessories
- Drill Bits
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- Hand Tools
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- Hand Planes
- Measuring Tools
Surface Prep 101
Once you finish constructing a woodworking project, you can move onto the finishing phase.
There are many ways to create a flat, smooth surface that a finish will adhere to. The most simple involves sandpaper.
You can use a simple sanding block to keep a flat surface or you can also use a power sander like a random orbit or belt sander. If you have more space and money, you can also buy a spindle sander that will help sanding curved surfaces.
As you woodworking skills develop, you may want to try handplaning a surface or using a card scraper. These techniques both require more skill and sharpening know-how, but learning how to properly use them is a fun woodworking challenge and the tools can also produce an unmatched surface.
The Right Grit from Start to Finish
Before we get into the sanding play-by-play, it's important to understand that there are two very distinct types of sandpaper which use different prefix lettes (either P or C). Most furniture makers generally stick to the FEPA scale, which uses the letter P. Just be sure to stick to one scale and avoid mixing and matching the different types of sandpaper.
Generally speaking, you can usually start out with a 120-grit sandpaper and simply work your way up the grit scale, all the way through 220-grit. Just be sure to clear the dust off your piece before switching grits, and don't continue to use a piece of sandpaper after it has become clogged. You'll just end up working harder, for less pay-off.
Sanding Tips & Tricks
Lets take a cabinet as an example: furniture maker David Sorg suggests sanding on the inside first:
If you start with the inside while you're fresh, you'll take an few extra minutes to do it right instead of skimping on it at the end.
For veneered plywood, you can start and stop with 180-grit paper if the inside will be minimally seen or used. Use a sanding block on the corners and on any more visible areas such as solid-wood edging.
Devote more time to visible areas and those likely to be touched. On end grain, go one grade finer so that it doesn't absorb the stain or clear finish as deeply.
For detail sanding, you could buy one of those high-priced detail sanders that come with a variety of pads and attachments designed to fit different profiles, but they can be a bit on the expensive side. Instead, consider using commercial rubber profiles that cover most convex and concave shapes, or make your own profile blocks from pieces of foam insulation (see below).
So how do you know when you'e finished sanding? Wipe on some mineral spirits and sight across the wood toward a strong light source. Look at the surface for telltale scratches. You're looking for a uniform appearance with no rough areas or single outstanding scratches.
Sanding Flat Areas
To maintain a flat surface, you should always use a sanding block when covering large areas. Sanding blocks can be easily found at any hardware store.
Sanding End Grain
Soften Your Edges
Break (or soften) the edges on a project to reduce the possibility of chips occurring on sharp corners, and to prevent finish from forming a mound at the edges. This technique also makes your furniture more comfortable to handle.
Blue rigid insulation foam (available at your local home center) makes a great backing for sandpaper. You can mold and shape this material to your heart's content.
Using a rubber pad that fits around your furniture's moldings helps keep the edges of the profiles sharp and crisp.