Shop safety first! Wear a good dust mask religiously! Sanding dust is no good for your health and lingers about in the air for a long time, so wear a mask. Having a fan blowing across your sanding area is a good idea and placing a furnace filter on the intake side will catch some dust. Safety goggles will keep dust from getting in your eyes. And if youíre doing a lot of hand sanding were a pair of gloves, this will keep the skin of your finger tips from wearing down so thin they bleed through the skin! Donít forget ear protection if youíre using a power sander. Ok, now that I have you looking like a doctor ready for brain surgeryÖletís get to it!
Generally speaking Iíll start out with 100 grit and work my way up using 150, 180 to 220. Getting the defects sanded out first with the 100 grit, then finer grits used for sanding thereafter are only needed to remove the previous scratches left behind by the previous sandpaper used. Thus 150 grit sands out the scratches left behind of the 100 grit and 180 sands out the scratches of the 150 grit and so on. Generally you wonít need to sand finer than 220, as film finishes such as varnishes, urethanes and lacquers will fill in those fine scratches making them invisible when applied.
Now with that being said; it does depend on what materials Iím sanding and the sanding objective. For example Iíll start right out with 180 or 220 on factory cherry veneered plywood, as itís pretty thin and generally doesnít require a whole lot of sanding. Unless there are some scratches or burnish marks from the handling process of the material, so then I may use a 150 grit. But be sure to use caution when sanding veneer as you can easily sand through them, especially if using a power sander! But then again factory oak veneer plywood can take a bit more sanding and I have stepped back to 150 and even 100 grit when required. Buying veneer to apply yourself will generally be thicker than the veneer face found on factory plywood, so you can get away with a little more sanding if needed.
If you have to remove a lot of material you can step things back to 80 or 50 grit. Onetime I had a solid oak table top to refinish that had a cigarette burn mark in the center of it. Of course the owner tried to sand out just the burn mark creating a divot and still didnít get all the burn mark out. In this case, the top happened to be a bit too cupped to run through my wide belt sander. So I broke out the handheld belt sander, starting out with 80 grit and sanding the entire top across the grain then sanding the entire top with the grain. This process lets you see where youíve sanded from the cross grain scratches and also removes the wood faster. You can continue with this method of sanding across the grain then with the grain until the last couple of passes need before you change to a finer grit. Then the rest of your sanding will be with the grain only, as you go through the finer grits! Sanding a larger surface as this, keep your belt sander moving at a consistent flow across the surface and overlap your passes by a quarter or a third. Belt sanders remove material pretty fast so keep the sander moving quite quickly and consistently, as to not sand too much in one area.
Be cautious of the edges when sanding, as material there will be removed more quickly, for the sanding pad will flex over the edge and even the looseness of the sandpaper on a sanding block will flex over the edge of the surface youíre sanding. And with power sanders you donít want to have them tip over the edge as youíre sanding, so just sand up to the edge and not over.
- Sandpaper will clog with sanding dust and develop hard dust nibs that can scratch your wood surface as your sanding causing you more work. You can keep these cleaned off by scraping them off with a putty knife or using a brass brush. Wood resin, glue, paint and other finishes will readily clog up your sand paper so change when needed.
- Using a something like a scotch pad between your sanding paper and sanding block will help the sanding process.
- When hand sanding Iíll tear the 8x11 sheets in half then tear those halves in half, so I end up with a quarter sheet. Then take the quarter sheet and fold it in thirds to sand with.
- When sanding larger surfaces, use a pencil to mark across the grain over the entire surface, making a line every three to four inches, this will help you know whatís has and has not been sanded. Also coloring in chip out with a pencil will help keep them located and when theyíve been fully sanded out.
- Using a low angled light shinning across the surface will help you see scratches that still need to be sanded out that were left behind by courser grits or swirl marks by a power sander. And this is a good tip for when applying finishes too!
- Using a rag dampened with mineral spirits prior to staining will help you identify any missed scratches or glue splotches that need additional attention.
- Vacuum up the dust off the surface with a dusting brush attachment or blow off with dry compressed air. Then use a tack cloth to wipe up the finer dust remaining prior to finishing. Caution, using a tack cloth prior to polyurethane application can cause the finish to crawl or ripple! So use a cloth dampened with mineral spirits instead when using polyurethane.
Happy Woodworking and Enjoy!
Author: James Simmons has over 10 years of custom carpentry and over 15 years of running his own custom woodshop crafting exclusive custom woodwork for million and billionaires. Over this time he has accumulated a ton of Valuable Woodworking Resources and sharing them at: http://www.WoodworkersProjects.info Plus you can Download over 16,000 Woodworking Plans and Designs at WoodworkersProjects.info