The relationship between sandpaper and finish has always been present, but with so much scrutiny on the final results and the “perfect finish,” the relationship can be tenuous. We want a scratch-free finish, and we still want maximum performance from our finishes. So, we run the fine line between sanding too fine and not fine enough.
First, always follow the finish manufacturer’s recommended sanding sequence. This is typically a wide range, maybe 80-120 grit, and as high as 150 with a multi-disc sander for some products. This is where it takes work. You have to try to figure out a recipe that works for you and the finishes that you work with most often. This can be done on a small test panel in your garage or shop. Always test the process before using it on a large project. If the finish doesn’t fail there, then you can go with confidence to the big floor.
The job of the sandpaper is to remove material and prep the surface for the next step in the process. The mineral, abrasive, definitely plays a role in how difficult it can be to leave a small scratch. Always buy quality paper. With wood floor sanding, we will always leave a scratch. Our goal is to make it so small it can’t be seen from a standing position. We must be careful not to burnish the floor by sanding too fine and keep the finish or stain from sticking or penetrating the wood floor. For example, if you sand a floor finer than the sample that you made for the customer, then apply the same color stain, you will have two different colors. Don’t call the manufacturer and tell them their stain is bad. This is user error. This is why you must develop a recipe and don’t deviate from it, ever.
Let’s walk through a generic sanding process from the beginning. Always start with a clean floor. New or old, it must be free of debris. Make the floor FLAT with the first cutting. Use a paper that is just aggressive enough for the task. If you can complete this with 80 grit, then by all means don’t use 60 grit. Vacuum the entire floor. This includes all the edges. Move through the grit sequence, being cautious not to skip more than one grit. This will show up in the final product. Vacuum in between each grit change.
The cleaner your floor stays, the nicer your finish will be. Debris is the enemy of the floor sander and finish of any type. No finish is immune to the effects of debris. Often a multi-disc sander will be substituted for the final sanding sequence(s), and many people will only use the multi-disc sander. That philosophy is a whole different rabbit hole.
After the final sanding and the floor has been vacuumed, don’t forget about vacuuming the tops of the baseboards, window sills, counter tops, fans, everything.
Now it’s time for my favorite tool, the Tampico Brush! This is the most underused and overlooked step that literally takes minutes to do, and will leave your finish looking amazing. This process must be done with the buffer attached to a vacuum to catch the fine dust that is pulled from all the little nooks and crannies. This step minimizes grain raise and saves both finish and applicators when applying penetrating finishes.
The floor is ready for the next step, which might be water popping, traditional oil stain, water-based stain, sealers, or penetrating finishes. Again, follow the finish manufacturer’s recommended sanding process. It is very common to sand to a 150 grit if water-based sealers are being used, in an effort to reduce grain raise. This process works well for water popping prior to stain application. You might only sand to 120 grit for a penetrating oil. Keep in mind that all of these sanding steps will affect the final color and how smooth the floor is. I can’t stress enough that if there is an imperfection, fix it before you move on to the next step. Scratches and sanding errors don’t ever get better with another coat of finish. One day of repairs/touchups is way less than having to re-sand an entire floor or room.
All of this information is available through the NWFA training program. We are able to explain and demo this process at these schools in a hands-on setting, but you must take this info home and implement it. Practice these techniques and they will soon become second nature. The nicest feeling is having a difficult sand job and not having to stress about the sanding process. I hope to see you at a school soon, and happy sanding.
Jason Elquest is the owner of Blackhawk Floors in Scottsdale, Arizona. He is an NWFA Certified Wood Flooring Inspector, Certified Installation Professional, Certified Sand & Finish Professional, an NWFA Regional Instructor, and serves on the NWFA Board of Directors and NWFA Certified Professionals Board. He can be reached at jason@blackhawkfloors.com.
