States that most furniture manufacturers seldom sand above 150 grit.ĭresdner offers the following rule of thumb for grit progression: jump under 100 points with coarse papers, 100 or more with medium, and 200 or more with very fine papers. Sanding to 200 grit and above will polish the surface and hinder pigment-stain penetration. He prefers to sand to 180 when applying a film finish (shellac, lacquer, varnish, conversion, or water-based) and 220 when applying a thin oil finish. So, what do the wood finishing experts do when it comes to sanding wood? Well, here’s what Bob Flexner, Michael Dresdner, Jim Tolpin, and Jeff Jewitt have to say:įlexner generally starts at 80 or 100 grit and seldom goes past 220. Silicon carbide sandpaper works well for sanding the finish because it is usually stearated or lubricated, preventing it from clogging up so quickly. Garnet continuously breaks down to expose fresh sharp edges (it is friable) but it is softer than aluminum oxide and thus better suited for hand-sanding. This can result in burnishing of the wood surface which affects penetration of the finish. Aluminum oxide lasts longer than garnet because it is harder but it doesn’t break down as well so the sharp edges become dull. In terms of sandpaper abrasives, a common approach is to start sanding with aluminum oxide sandpaper using a power sander and then switch to garnet paper for final sanding by hand. Summary: A good general rule for grit progression is to use 100 or 120 grit for initial sanding, 150 or 180 grit for the next pass, and 220 grit for the final pass. It can also help to lightly dampen the surface with mineral spirits or water. If you see any residual scratches, keep sanding. Then, look at the wood surface with a low angle light. First, vacuum or wipe off the sanding dust. How do you know when to stop sanding? This is something you gain with experience but there is a simple way to determine if more sanding is required. Note that in addition to wasting your time, excessive sanding can also impair the absorption of certain stains. Test this yourself the next time you’re finishing a project. A 400 grit surface won’t look appreciably different than a 180 grit surface. If you sand beyond this level, the wood will look more polished but after applying the finish, the polish goes away. In most cases, the wood will be ready for finishing after this third pass. Perform a final sanding pass using a very fine grit – 220 to 240 (I prefer 220 grit). That will actually take longer because the finer grit will be much less effective at removing the initial sanding marks. Don’t be tempted to “skip a grit” by going right to 220 or higher. This will be the next finer level of coarseness - 150 or 180 grit (if you started at 80 to 120 grit). Vacuum off the dust from the first sanding pass and move onto the next grit. But if you have deep gouges in the wood or it has pronounced “washboard” ripples from the planer, you may well have to start sanding at 80 grit. That will just put down deep scratches that you then have to remove. It’s counterproductive to start at 80 grit in many situations. If the milling marks are not very obvious, you can usually start at 100 or maybe even 120. Use your best judgment and experience here. In most situations, that will be 80 to 120 grit. So it’s onto the grits…īegin sanding with the finest grit that’s capable of removing the machine marks and other imperfections on the wood. But hand tools aren’t for everyone and some tasks are easier done with sandpaper. Make a few quick passes to remove the mill marks and other defects and move on to the finishing. Quick aside: If one is proficient with hand planes and scrapers, it may not be necessary to sand at all. That’s the gist of going through the grits. Eventually the wood will reach the desired smoothness. Then, it’s a matter of sanding the wood with progressively finer and finer grits with each grit removing the scratches from the previous grit and replacing them with denser but shallower ones. This is most efficiently done by first sanding the wood with a coarse enough grit to remove the blemishes. Keep in mind that the purpose of sanding is to remove mill marks on the wood created by woodworking machinery – planers, saws, jointers, etc., as well as any scratches, dents, burns, and other defects. This process is sometimes referred to as a sanding schedule or sanding sequence or more simply, going through the grits. That is: what grit to start with, what grit to end with, and what grits to use in between. Sanding is not the most pleasant woodworking task but it goes a lot smoother (pun intended) if you have a system in place for choosing sandpaper grits.
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