Sanding – Unmasking the Mystique – Program following 3/15/14 Meeting
Julie Wing began with a handout, updated from her 2008 talk. Call or email her for this handout. She told the history of sandpaper, first used in China. The types of abrasives were outlined: flint (not recommended), garnet (one of Julie’s favorites), aluminum oxide (the most popular for woodworking), emery (a distinctive black color), silicone carbide (used wet or dry), and Abernet (open weave, soft backing) that a lot of driftwooders like. (Abernet is expensive, can be found at Woodcraft in Seattle – good on pitch. Julie uses it up to 320 only; she finds the finer grits make scratches.) She showed 3M Sandblaster in 4 different colors to denote grit sizes. Foam-backed sanding pieces are popular. She showed a wide variety of sanding tools. Julie emphasized that flexible backings are important for our work. She explained open coat vs. closed coat, relating to how the surface is covered with abrasive. Open coat is best for our general needs; closed coat is better suited for finish sanding by hand.
Sandpaper comes in many different styles and forms: sheets, belts, discs, rolls, sponges and specialty pre-cut shapes. Julie said sandpaper works like, and should be thought of as, a cutting tool.
Although it seems tedious and time consuming, sanding is our most important work. It is crucial to a well finished project. It is the simplest of woodworking tools to learn and most important for achieving a quality finish. Don’t start sanding too soon! It is important that all unwanted or soft wood is scraped off first. It is very important to go through all the grits in order from coarse to fine. Start with 100 or 120 grit, then 180, on to 240, then 320 – and above if desired. Don’t be tempted to skip a grit; scratches will result. As you progress in grits, vacuum or brush away the dust as you sand (and clean the sandpaper on your towel). A tack, soft, or Swiffer cloth is helpful in removing dust.
-Sand with the grain of the piece (sometimes sanding angularly will work), using long, even strokes, back and forth, with an even pressure.
-Sand with the same grit throughout the whole piece before changing grits. One grit at a time!
-Sanding odd shaped pieces requires some ingenuity. Sandpaper can be rolled, put over a rubber ‘tadpole’ or sponge or hose piece, affixed to a dowel with contact cement or durabond. Make your own emery boards by gluing to tongue depressors (mark grit size on back), credit cards, etc. (or use adhesive-backed papers). Using a sanding block or pad (or sponge or cut-up mouse pad) is helpful in evenly distributing the pressure of the sandpaper. If you feel heat, you are pressing too hard. Let the sandpaper do the work.
-Don’t rely on boning to finish a piece. Incomplete sanding will show up as muted scratches on the surface of the wood.
-To check your sanding surface, look at it in the sunlight or under a low angled backlight – imperfections will show up and can be corrected before the finish is applied.
-If the sandpaper is no longer cutting the surface effectively, discard it and get another piece. Toss out that bag of old sandpaper pieces now! A fresh piece will allow you to work more quickly and efficiently. Sanding wood takes considerable effort; new sandpaper is inexpensive compared to your effort.
-When do you move from one grit to the next? When a uniform look and feel has been achieved.
-When do you stop? When the smoothness you want is achieved.
Power sanding: There is a large variety of tools available: belt sanders, disc sanders, drum sanders, pad sanders, random orbit sanders, various rotary tool sanders. All are helpful but caution must be used. It is possible to remove too much wood or leave the surface marred with accidental gouging. Power tools are not used in final sanding. Final sanding must be done by hand.
Wear safety glasses and a dust mask (N95 rating) or respirator every time. Toxic dust may emanate from certain woods or molds and fungus in our wood. A dust collector is recommended.
• Purchase good quality sandpaper; it will save time by doing its job right the first time.
• Refold or shift the sandpaper on the block often to expose a fresh cutting surface.
• Use rubbing alcohol or heat gun to remove pitch from the wood before sanding.
• To remove ‘stuck’ sanding drum, place in the freezer for a few minutes. It will contract, making removal easier.
• Use anti-vibration gloves when power sanding for more comfort.
• Use an abrasive cleaning stick (sandpaper eraser) to clean sandpaper, especially for power sanding.
• Attach sandpaper to thin strips of wood with double-back tape to get into narrow, tight spots.
• Using a vise is helpful when needing to have your piece steady when sanding.
• Use a pencil line, in a zigzag motion across the surface still to be sanded, especially when you are interrupted.
• Swiffer sheets or microfiber cloths are good dust removers.
• When using a flap sander, use on a slow speed only. Faster speeds only burnish the wood.
Remember: For the love of the wood, you need to put in the time. Bring out the beauty the wood deserves!
(If you are in Bellingham, Julie recommends Hardware Sales on State and James for great sanding tool variety, though not on Sundays. Dick Kite said he uses the back side of cloth-backed sanding sheets to polish wood.)
Enormous thanks to Julie for an excellent presentation! /jrm
(And thank YOU, Jo Marsh, for the excellent write up.