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Shop Tips & Tricks #18: The Zen of Sandpaper and Sanding

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Blog entry by GnarlyErik posted 11-19-2016 01:34 AM 1596 reads 1 time favorited 5 comments Add to Favorites Watch
« Part 17: Making Painting & Varnishing Easier, Cleaner and Cheaper Part 18 of Shop Tips & Tricks series Part 19: The Art of Middles of Symmetries »

Many wood workers will already know these things, but for those who do not, here are a few pointers and shortcuts about sandpaper and sanding – things I’ve learned after decades of wearing my fingerprints off.

THERE IS NO SUCH THING AS ‘NO SAND FINISHING’, and never let any smooth-talking paint salesperson tell you otherwise! Almost all woodworking projects need finish work. Most finishes require smoothing before the finish is applied. Normally, that means SANDING – usually, that’s the least favorite part of most woodworking projects, although I can get into a zen trance with a lot of repetitive sanding. I sometimes wear off my fingerprints so much my tablet with fingerprint recognition no longer recognizes them!

Tip #1: Tape your fingertips with masking tape to save your skin for anything requiring a lot of sandpaper time. By the time you you wonder why your fingers are feeling sore it will be too late!

‘Sanding’ gets its name from the grit used to smooth everything from wooden spoons to seashells to nude statues made from the finest of marbles since before recorded history. And of course ‘sandpaper’ is paper (or cloth, or other material) with an abrasive grit uniformly glued to its surface. The ‘grit’ may be an actual ‘sand’ like finely ground garnet, emery, silicon carbide, diamond (dust) or other materials such as aluminum oxide._ From Wikipediahttps://en.m.wikipedia.org/wiki/Sandpaper#/search_: There are many varieties of sandpaper, with variations in the paper or backing, the material used for the grit, grit size, and the bond.

Grit fineness for sandpaper used for woods is usually denoted by a number – the higher the number, the finer the grit. Grit size can range from 16 (or lower!) to over 1000, with the most common for woods being 60, 80, 100, 120, 150, 180, 220, 320, 420 and 600. There are grit sizes available ranging from 1000 up to over 12000, which are used for polishing. Technicians may use 3000 & 6000 for polishing scratches out of perplex canopies on fighter jets for example. You can find the higher number grit papers at auto parts stores, or at Home Depot. I use the 3000 (wet or dry) for edge tools sometimes.

The paper backing size (weight of the paper) is denoted by a letter, with “A” being heaviest to “F”, the lightest. The most common size for sandpaper sheets is 9” x 11”.

Tip #2: Fold a sheet of sandpaper in half on the short dimension and cut along the fold to end with two pieces of 9” x 5-1/2”. Now fold each piece in thirds to obtain an easily handled arrangement which will not slip against itself when used for hand sanding.

You can buy rubber sanding blocks which have their uses. But, I like to make my own which better suit my needs. I like a stiffer wooden block much better than store bought rubber ones and those can be made for nothing from scraps and cut-offs. Wooden ones work better for sanding inside corners and long flats too for me.

Tip #3: Make your own wooden half-sheet sanding blocks. This will take a block 5” x 2-3/4” x 1-1/2”. Make a ‘clamping block’ 1/4” to 1/2” smaller to hold the sandpaper. A couple of screws hold the clamping block tightly in place. If you mark the matching ends of both the sanding block and its clamp, the screws will usually find their former holes each time you refill your block with new sandpaper. I like to have two or three so I can fit different grit sizes to suit either rough or finish sanding.

(It helps to use a couple of spring clamps to hold things as you screw on the clamping block)

Tip #4: Make your own wooden quarter-sheet sanding blocks. Ditto Tip #3, except the sanding block size is now 5” x 1-3’8” x 3/4”.

Sandpaper is employed for uses besides finish sanding wood. You can use it to shape things too, with the lower number grit sizes being most effective for removing stock or ‘wearing wood’ as the old-timers used to say. Here it is employed like a ‘mini-rasp’, especially for curved shapes. Depending upon what I am trying to do, I make a special shaped block or shape to fit the need. I never throw these one-off tools away either. It is amazing how often I find these ‘special shape’ will be just the ticket for something in the future. These custom blocks are kept in a ‘root-box’ which can be rooted around in to find a shape needed.

Sometimes the shape needed won’t accommodate a clamp to hold the sandpaper, and here is where contact cement comes into play. I love the kind that comes in a spray can for these small needs.

Tip #5: Make your own special needs sanding blocks or mini-rasps to exactly fit what you need to do. Here are a few from my root box:

I dislike finding my sandpaper all curled up from humidity. There are ways to deal with this. Some store sandpaper in a bin, with a piece of wood or weight on top. I use two pieces of masonite, or other flat, thin stuff and place the sandpaper sheets between them, all held together by a spring clamp. This can be carried to a work location to keep a selection of weights and grits handy.

Tip #6: Keeping your sandpaper flat. See the photo explanation:

Carrying the above idea one step further, this works just as well as for partial sheets and used sandpaper which still has life in it. This has the bonus of being portable and can be carried around so you have several weights of sandpaper available without having to go back to your bench or bin.

Tip #7: Sharpening things with sandpaper: Wet or dry paper can be used for sharpening, especially things that are too big for your grinder or oil stones. Using a very fine grit, you can put a new edge on planer knives, scissors, pocketknives and chisels. You will want to use fine grits of course – 600 or above, and back the sandpaper with something perfectly flat. A piece of plate glass works very well. Place the glass flat on your bench with the wet or dry paper on it and use it like a large whetstone, using plenty or water or oil as a lubricant. You will be amazed what this can do for dull scissors for example.

Tip #8: Use a similar trick to make something perfectly flat. You start off with a fairly coarse grit to begin working something down to perfectly flat and true, using successively finer grits as you proceed. When your whetstones get dished out for example, dress them perfectly flat again using wet or dry sandpaper on glass, lubricant, elbow grease and patience.

I hope you can use a few of these ideas to help you make a necessary chore easier!

-- "Never let your dogma be run over by your karma!"



5 comments so far

View Mrkixx's profile

Mrkixx

71 posts in 1944 days


#1 posted 11-19-2016 03:45 AM

Great tips thank you. I especially like the finger saver, I’m going to try that next time. My fingert have been so bad that they bled and I could not figure out why, and man did they hurt. I always figured that I didn’t need a sanding block, but I will be making some in the near future. Thanks again

View Texcaster's profile

Texcaster

1273 posts in 1638 days


#2 posted 11-19-2016 07:31 AM

You’ve covered a necessary activity very well. You didn’t mention “Sanders Helper”, now legal in many states.

-- Mama calls me Texcaster but my real name is Mr. Earl.

View GnarlyErik's profile

GnarlyErik

307 posts in 2099 days


#3 posted 11-19-2016 12:51 PM

Thanks for both comments.

Mr. Texcaster, I see you are a Luthier. I’ve always admired the luthier art and have just built my first instrument which I will post soon. I do not play myself, but my wife loves it. I have enjoyed the process immensely.

There are two more in the making also, which I will post when done.

Cheers,
Erik

-- "Never let your dogma be run over by your karma!"

View Gene Howe's profile

Gene Howe

10350 posts in 3393 days


#4 posted 11-19-2016 12:57 PM

Great post. Thanks for the tips.

-- Gene 'The true soldier fights not because he hates what is in front of him, but because he loves what is behind him.' G. K. Chesterton

View bhuvi's profile

bhuvi

97 posts in 506 days


#5 posted 12-01-2016 02:15 PM

-- Do NOT click links. Spammer in the process of being removed.

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