Way too many people work way too hard when it comes to sanding wood surfaces. Learn how to use sandpaper efficiently so you can minimize your personal energy.
The second step in furniture refinishing (or the first step in furniture finishing) is to prepare the surface for staining and/or clear coating. In this article and in my video I will teach you the basics of sanding wood effortlessly.
Be sure to download and print my PDF Cheat Sheet: “Sanding Rules, Tips, Techniques and Paraphernalia”
You’ll find this, as all my articles and videos a detailed step by step guide to the sanding process. As an option you can watch my YouTube video “Sanding Wood Efficiently – The Second Step in Furniture Refinishing” and my entire finishing and refinishing video series where I visually demonstrate the correct steps in assuring a quality finish.
Sanding wood is by far the least favorite part of finishing and refinishing for most DIYers. That’s because most DIYers make it harder than it should be. If you follow my rules and learn the basics, you’ll be amazed at how easy this step in the finishing process is and how much a properly prepared surface will enhance the beauty of you project.
If yours is a new project you’ve recently assembled it will undoubtedly have mill marks as most lumber is run through commercial saws and planers to prep each board for sale. If yours is a refinishing project you’ll probably have scratches, dents and gouges common to previously used furniture.
Also you’ve probably removed old layers of paint or varnish with a chemical stripper or heat gun. Staining raw wood causes “grain raise” a fuzziness after wetting wood that is analogous to the fizziness that happens after shampooing your hair. All play havoc with wood and the surface will need a little TLC to restore it to its one-time glorious state. The problem is most people make sanding wood more difficult than it should be
Let’s look at the materials you’ll need:
A generous variety GRIT SANDPAPERS
Flat Wooden Block or Rubber Sanding Block
OPTIONAL BUT HELPFUL: A Mechanical Sander (If you have a choice of only one I recommend as the best all around sander – Random Orbital Sander)
A beautiful finish starts with a good surface. Sanding is the key to a good surface. Sandpaper is measured in grits with the lower the number the coarser the paper. Coarser grits can tear out chucks of wood fibers whereas high grits actually polish the wood fibers. Sanding wood creates scratches in the surface. Each step higher in grit smooths over the scratching created by the previous lower grit sanding.
Sanding should always be done in steps moving to a higher grit (finer) sandpaper with each progressive step. Skipping a step actually slows the sanding process as it forces a paper to attempt to do work it was not intended to do. When efficiency is lost – energy is expended. You the woodworker suffer for skipping the in-between grit.
SANDING WOOD SURFACES IS BEST DONE IN STEPS
START WITH THE COARSEST GRIT APPROPRIATE FOR YOUR PROJECTS REQUIREMENTS
Starting with the coarsest grit sandpaper saves time and energy. That said, if you choose a grit that’s too coarse for your project you’re wasting time. Now I sound like a politician talking out both sides of my mouth!! Let me explain:
If your project is in need of leveling start at 40 to 80 grit
If your project has gouges, deep scratches, some left over paint or varnish start with (or move up to) 100 grit
Without any of the above conditions or when done correcting the above conditions start with (or move up to) 120 grit.
Always follow 120 grit with 180 grit. If you are using a film-based clear coating (spar varnish, marine varnish, polyurethane, shellac, or lacquer) as your final finishing step you are done sanding until after you stain or after you apply your first top coat.
For the above film-based clear coats you should sand LIGHTLY with 220 grit between each coat.
TIP: I always wait a day to apply a second coat of film-based clear coats. I want the surface to be dry so I can see and feel the surface for any minor imperfections. If there are imperfections now is the time to correct them. It doesn’t make sense to put the next coat over a bad layer.
If you are using a penetrating oil as your final finishing step after 220 grit sand next with 300 grit followed by 400 grit.
EFFICIENT SANDING REQUIRES LETTING THE SANDPAPER DO THE WORK
The hard work in sanding is in the REPAIR PROCESS which relate to correcting flaws. Leveling and removing deep scratches, gouges and old finish is the grunt part. If you follow each progressive grit step sequentially you’ll find each sanding step is progressively easier and faster than the previous one.
Again, that is unless you skip a step in which case sanding with too fine a grit translates into hard work. The moral here is let the sandpaper do the work it was intended to do by selecting:
THE RIGHT GRIT – FOR THE RIGHT PURPOSE – IN THE RIGHT SEQUENCE!
Download and save my printable PDF Cheat Sheet
“Woodworkers Sandpaper Grit Selection Chart”
Watch my video Choosing The Right Grade Sandpaper for Your Woodworking Project.
For most projects 120 grit is the true workhorse. For wood it is considered a medium grit capable of removing a good amount of wood with relative ease. The other benefit of starting at 120 is there isn’t the likelihood of doing a lot of damage like its lower grit cousins.
The next step would be to move to a 180 grit paper. This will reduce virtually all the scratches left by the lower grits to an unobservable point IF your project is to be clear coated with a film coating. Film coatings include varnishes (including polyurethane), shellac, varnish or lacquer. Since most projects by most DIYers will be film coated in their final step the minor scratching of 180 grit will not be noticed.
If you are going to be using a penetrating oil type finish I would recommend taking your sanding steps to a minimum of 320 grit and my preference is to 400 grit. Penetrating oils absorb in between the wood fibers and because they SOAK-IN they tend to show off even minor scratching.
Repair projects where 80-100 grit sandpaper should be used is best done with a mechanical sander. While this can be done by hand sanding it does require energy. Mechanical sanders have made the life of refinishers and woodworkers very easy and the cost has become so that even an occasional DIYer can justify the expense.
IMPORTANT CAVEAT: SANDING PLYWOOD
Plywood is made from layers of wood and wood byproducts with a very thin layer of quality wood veneer on top. While there are many advantages to plywood the major drawback is the potential to cut through the top veneer layer. Extra caution is required when sanding plywoods.
Mechanical sanders and low grit sand paper tear through wood quickly. When sanding it is best to use minimal pressure. Too much pressure will create uneven surface areas and create deeper scratches.
WHY SANDING WOOD IN THE DIRECTION OF THE GRAIN IS IMPORTANT
Determine the direction of the wood grain and follow that direction when sanding. Wood fibers grow in one direction and going across that direction cuts into the wood fiber’s membrane. Cut wood grains show as scratches and open up the fiber membrane which in turn absorbs more stain or top coat. This creates unevenness in both stain color (stain blotches) and top coat appearance.
Sanding wood with the grain not only removes surface unevenness but removes any areas where the grain has raised (kinda like split ends in human hair).
There are exceptions. Sometimes repair requires sanding in direction that doesn’t follow the grain. This should be avoided whenever possible but when you must go against the natural grain to repair or level an area be sure to follow up with the same grit until the cross scratches are removed. This is done to repair or remove damaged fibers.
EFFICIENT HAND SANDING
Use an open hand with properly folded sandpaper or attach to a sanding block. For removing deep scratches, gouges, lumber yard milling marks, raised surfaces and paint or varnish spots I like the feel of the paper under my hand or fingers as I feel it gives me better control. This is where the most time and energy is expended in the sanding process. Once the repair process is complete I move 120 grit paper and sand the entire surface following the grain of the wood. When possible and on flat surfaces use a sanding block vs open hand to assure the surface is even. The last step will be the highest grit based on your choice of clear finish.
TIP: FOLDING SANDPAPER – Sandpaper typically comes in 9X11” sheets or 3.67X9” strips. The largest section for effective hand sanding would be folded into quarter sheets for sheet paper or in half for strip paper.
EFFICIENT MECHANICAL SANDING
Let me start by saying that YOU DON”T NEED A MECHANICAL SANDER TO SAND YOUR PROJECT but it makes life easier and sanding faster. Early in my woodworking evolution I appreciated a good finish. It took me awhile to realize that a correct sanding procedures were critical to a good finish. I overworked almost every project because I didn’t understand the efficiency of sanding in sequential steps. My thought process at the time was that sanding was the hard part and I needed a mechanical sander to lessen my work load. I was elated when I bought my first power sander.
I was disappointed that the mechanical sander still took a lot of time and a lot of energy. It took years for me to learn the errors in my approach. I am now the Tim Taylor (Tool Time Character) of sanding equipment. You name it I probably have it! But even with all that I typically finish with a final HAND sanding.
TIP: The most time and energy can be saved by choosing THE RIGHT GRIT, FOR THE RIGHT PURPOSE, IN THE RIGHT SEQUENCE.
TIP: SANDING SPEED. Moving too fast with mechanical sanders might create unwanted scratches. The general rule for mechanical sanders is move no faster than ONE INCH PER SECOND. I follow this tip closely for all raw wood sanding. I break this rule when sanding between film-based top coats. Since scratches aren’t apparent above a 180 grit in film coats and I use a 220 grit to sand between coats I feel safe violating the speed rule.
TIP: HAND SAND AS A FINAL TO MECHANICAL SANDING. Mechanical sanding should always be finished with a light hand sanding in the direction of the grain. This last step assures that squigglies and swirls common to mechanical sanders have been minimized.
EFFICIENT SANDING – CHOOSING A MECHANICAL SANDER
Okay let’s look at what’s available and what might best suit your needs.
BELT SANDERS – Belt sanders are the bulldozers of the woodworking industry. They have many advantages and a few disadvantages. They are portable, as opposed to table top or stationary machines. They remove a lot of material quickly. They are good for leveling uneven surfaces.
On the downside. They remove a lot of material quickly. This makes them dangerous and impractical for the finish stages of sanding. Even experienced woodworkers have slipped and removed too much surface as it happens so quickly. They are heavy. They are expensive. They are loud.
ORBITAL SANDERS – Orbital sanders move in a small elliptical pattern and are capable of removing a good amount of wood fiber easily. This is probably my favorite especially when down to the finer grit sanding, sanding after staining and between coats of clear top coating.
PROS: They are faster than hand sanding. They remove a reasonable amount of wood fiber with minimal chance of mistakes. They fit nicely into square corners. They are good for softening sharp edges. Light weight. Easy to master. Reasonably priced. Sandpapers are inexpensive.
CONS: Must be used properly or will leave swirl marks (see TIP: SANDING SPEED above). Not good for leveling.
RANDOM ORBITAL SANDERS – Random orbital sanders are a nice cross between a belt sander and an orbital sander. Random orbital sander move in two directions. They spin and they move in an elliptical pattern as they spin. This virtually assures that no pattern will ever be repeated eliminating swirl marks.
PROS: They can remove a lot of material quickly and can be used in the final finishing steps. They are therefore a good multipurpose sander. They are modestly priced. Heavier than an orbital sander but not as heavy as a belt sander. Good for polishing as well as sanding.
CONS: Don’t fit into framed corners. Sandpapers are expensive. Requires some practice to use properly.
DETAIL SANDER – small triangular shaped orbital sander that fits in tight places.
PROS: Good for tight places and hobbyists.
CONS: Limited use. Papers are expensive and often difficult to obtain after market.
EFFICIENT SANDING BEFORE STAINING
Sanding too fine retards absorption of stain. If you will be staining it is most often not advisable to go higher than a 180 grit sandpaper. The exception is if you don’t want a lot of stain color.
The most recommended method for dust removal is a vacuum cleaner with a brush attachment followed by a very light wipe down with tack cloth. Tack cloth is cheese cloth with a bit of tacky substance commercially prepared. It is possible to make your own tack cloth but it’s so inexpensive I just purchase it at any paint store, home center or hardware store.
Okay my disclaimer. Here’s what I have been doing for 35 years of woodworking: I use an air compressor to blow off dust!! Granted this creates air borne dust but I never apply coatings the same day I sand. And, come on, sanding itself creates airborne dust so se-la-vie. Unless you are in a microchip lab there will be dust!!
An air compressor probably possesses 20 times the removal power of a typical shop vac and empties the wood pores which vacuum cleaners tend not to do. The next day before I apply stain or clear coat I tack cloth the surface first and wah-lah. If you are going to use an air compressor you need a filter to assure you are not blowing water or worse yet oil onto your project.
TIP: Dust nibs are common to many DIYer’s. Nibs happen because of airborne particles but they are also introduced by contaminated brushes or coatings. I keep my brushes in my shop but after they are thoroughly cleaned and dried I place them in a plastic baggy because in my shop, I’m always making saw dust and finer dust penetrates EVERYTHING, EVERYWHERE. The outside (and inside) of stain and clear coat cans should be dust free as well.
TIP: Dust nibs after your final coat are best removed by using a brown paper bag (hard to find these days) folded flat. The bag is coarse enough to remove any high spots without scratching the surface and changing the finishes sheen.
Understand the basic rules and always remember my sanding motto:
Choose THE RIGHT GRIT – FOR THE RIGHT PURPOSE – IN THE RIGHT SEQUENCE
My Refinishing Furniture YouTube Library:
Chemical Strippers vs Heat Gun – Refinishing Furniture
Sanding Efficiently – The Second Step In Refinishing Furniture
Choosing the Right Grade Sandpaper for Your Woodworking Project – Refinishing Furniture
Blotch-Free Wood Stain Application Technique – Refinishing Furniture
Bubble-Free Polyurethane Application Technique
When and How to Wipe On Polyurethane – Refinishing Furniture
Ultimate Guide to Bubble Free Varnish – Doors, Furniture, Cabinets, Tables
Fixing Polyurethane Bubbles, Puddles, Runs and Brush Marks
Proper Brush Cleaning – Paint, Polyurethane, Varnish, Shellac
Refinishing Furniture PDF Summary Sheets Available for Download and Printing:
Polyurethane – Rules, Tips and Paraphernalia PDF
Stripper – Rules, Tips and Paraphernalia PDF
Sanding – Rules, Tips and Paraphernalia PDF
Choosing the Right Grade Sandpaper (Chart) PDF
Staining – Rules, Tips and Paraphernalia PDF
Wipe On Polyurethane – Rules, Tips and Paraphernalia PDF
Hopefully this isn’t the end but instead a great finish