Sanding and Sandpapers

by Garrett Lambert and Scott Greaves, with contributions from Dave Anderson, Mike Circo, Andy Lincoln, John Richards, George W. Dart, Mark Mandell, Mark Kauder and Bill Smith

Garrettt Lambert:

All woodworkers use sandpaper, but in my experience, very few think about it in the same way they would one of their other cutting tools. Yet, the paper and the way it's used probably have a greater impact on a project's final appearance than any other single step in the production process!

Some don't realize that we don't have to sand at all. A surface that has been planed or scraped with a properly honed iron or card has no scratches, the pores of the wood are clear, and the ends of the fibres have been cleanly sheared away. The figure leaps out, and the surface has a luminous quality. A well-planed or scraped board will always stand out against its mate that has been sanded - no matter how well - and will be seen as much more attractive and appealing to the eye. Unfortunately, just as we tend not to think about sanding - a necessary evil almost everyone dislikes and that is intrinsically unhealthy because of the very fine dust it produces - the majority of us are power tool lovers who never learn how to properly sharpen and use a plane or scraper.

So we sand, a process that leaves marks from the random, wearing action of lots of tiny, hard particles. At some point in the sanding process, the marks, although still there, become fine enough that the human eye does not remark them. However, the pores of the wood have become filled with dust, and the ends of the wood fibres are left ground down.

Someone observed that finishing is the biggest part of a project, but the least understood. Sandpaper is a perfect example of this truism. Taken together, sandpaper grits comprise a carefully designed system to get a product from machine marks to those "invisible" scratches. As with any system, it's essential to follow the progression of grits exactly. 100 grit paper is designed to remove the marks left by 80 grit paper, and so on up the line. Skip grits and you can sand forever, but you will never get the surface you strive for. Do it in progression, and each step should take very little time unless, of course, you're sanding vast areas. If you find that a particular grit wears out before doing its job, it's probably an indication that you failed to complete an earlier grit properly. With a light shining on the work from a relatively low angle, it's easy to see when the last grit's marks have been replaced by finer ones and that it's time to move on.

Mark Mandell suggests using less pressure and you'll be less likely to break granules off the paper. "Most people unconsciously press on their abrasives harder than necessary to get the job done. A shop vac with brush attachment should always be used between grit-changes to remove granules. Bill Smith says he uses compressed air between each grit and on the sandpaper itself to ensure that it is clean.

Yes, sanding can be boring, but usually we get frustrated rather than bored, because we think we can take shortcuts. For "fun", try sanding a small piece and doing it step-by-step using good quality papers. You will be pleasantly surprised at how quickly you proceed and how good the result is. BTW, for more information on technique, read Russ Fairfield's "My 5 Rules of Sanding".

If there's any good news about sanding, it's how much the quality of the product has improved over time. Five decades ago, my father's woodworking business used only the 3M orange-coloured garnet paper, and swore by it. By today's standards, it's mediocre. Once, in a Saturday rush, I bought several mixed packages of khaki-coloured "glass" paper of a no-name Taiwanese variety. The adhesive is poor and the grit falls away rapidly, and contaminates the work-piece. A waste not only of money but of time and effort.

Shortly thereafter, I purchased a 25 pound box of Klingspor (Germany) "ends" for turning from Lee Valley Tools. These are excellent papers, and I recommend them highly. Unfortunately, LV has stopped selling them. However, John Richards reports that Klingspor has a woodshop/shipping center in NC where they sell their paper at good prices and he notes that it really does last a long time. The store also has a closeout bin that you can dig through to buy cloth backed paper by the pound, but if you don't live in the Tarheel state, you can buy through their website at www.woodworkingshop.com. When Mike Circo tried Klingspor sandpaper pads for his Bosch ROS, although satisfied with the product, he found it not readily available and expensive. He reports his experience with Norton abrasives "disappointing. They dulled very quickly, and the thin backing tore very easily." On a whim, he tried the Ace Hardware branded paper at his local store. "Very inexpensive and very nice. The abrasive stays attached to the backing. It lasts a long time. The paper backing is quite durable and stiff which avoids rounding over edges. I started using Ace Hardware sanding supplies initially for the convenience, but now prefer them for the cost/performance."