Sanding System and Grit Sequence
Choosing sandpaper and grit sequence when sanding a floor plays a major factor in the looks and ultimately the life of the floor. A typical solid three-quarter inch tongue and groove wood floor can be resanded many times by a competent professional flooring contractor. Contractors sanding a wood floor have a huge responsibility to protect the investment of the client and make sure the floor lasts as long as possible.
The majority of flooring contractors use the exact sanding system they were taught from day one many years ago. But the flooring industry continues to make advancements in technology every year. Abrasives, machines, and finishes are much better now than even five years ago. At 12th & Oak, we continue our training and education yearly to stay on top of the latest techniques and products. Using their same old system, some contractors continue to choose a too aggressive grit of sandpaper to start with and then skip too many grits between sandpaper. By doing this, they are unnecessarily sanding valuable material off the floor, decreasing the overall life and sometimes leaving little or no wood for the next sanding. This process also creates deep scratches that cannot be sanded when skipping too many grits.
The Goal for any sanding system is to use progressively finer grits to remove old finishes, flatten, and smooth the wood to prepare it for new stain and/or the new finishes, all the while removing as little material possible from the wear layer. By only removing the material necessary it ensures that your floor will last a lifetime.
Sandpaper for hardwood flooring comes in many different grits. 12, 16, 20, 24 grits are considered an “open coat” abrasive. These grits are very aggressive and are used to remove years of wax and other contaminants from your hardwood floor. Floors that need these “open coat” abrasives are very rare in our area. 30, 36, and 40 grit are called “coarse” abrasives, and are used for fast flattening of poorly milled wood or wood that is heavily worn and damaged. “Medium” abrasives come in 50 and 60 grit paper and is where the 12th & Oak Sanding System begins our grit selection. “Fine” abrasives are 80, and 100 grits and “Extra Fine” abrasives are 120 and 150 grits.
It is imperative not to skip more than one grit of abrasive at any time. Most contractors sanding sequences start at 36 grit; they skip the 40, 50, 60 grits, and go straight to 80 grit. This saves them lots of time, labor, and money, but to the detriment of your hardwood floors. It’s likely by starting with 36 grit they are removing an unnecessary amount of the wear layer resulting in less wood available to sand in the future. By starting with such a coarse grit abrasive, deep scratches are created in the hardwood, and by jumping straight to a fine grit abrasive, they are only able to sand the tops/peaks of those scratches, leaving the deeper scratch marks behind. By not removing the deeper scratch marks it leaves a rougher surface that is visible and will cause the finish to wear much faster because of these peaks and valleys.
This popular 36-to-80 grit progression is known as the “Chicago Special” and leaves hideous sanding marks and a rough surface on which finishes adhere. If you are in someone’s house and see lots of wear in the high-traffic areas only a couple of years after a refinish, this is likely one of the major causes. This style of finishing is prevalent in homes in the Raleigh-Durham area.
Throughout the 12th & Oak sanding process, we use many different types of sanding machines that require different grits of paper for their individual uses. The main machine we employ for this system are our Lagler Hummel aka (“Big Machine”), which is used to sand in large open areas (“the field”) of the floor. We use the Lagler Flip and the American Sanders B2+ sanders around the edges in places where the Big Machine cannot reach. One of the machines that separate us from other contractors is our utilization of a planetary sander, the Bona PowerDrive or Lagler Trio (Planetary Sanders), to fine sand the entire floor to about 1.5” from the walls. Anywhere not reached by the PowerDrive and Trio we use our Festool RO 150 and 90 to blend those areas.
Our standard sanding process on a floor would begin on our Lagler Hummel with 60 grit ceramic abrasive sanding on a 7-15 degree angle to flatten and remove the old finish. Next, we follow with 80 grit on the Big Machine. 60 grit on the Lagler Flip. We will then use our PowerDrive or Trio with 80grit then 100 and/or 120 grit depending on the stain and finish. In this example, we started with 60 grit then went to 80 grit on our Lagler Hummel. After the big machine and edge sanding are completed, we follow it with our Planetary Sander beginning with the same grit we finished with on the Big Machine. In this case that’s 80 grit, then 100 grit, and, in some cases, 120 grit.
This is what separates the 12th & Oak Sanding System from the other contractors in our area. We only use the finest machines and abrasives on the market, that leave the best finish in the industry. We don’t believe in using cheap, inferior, products at any point in our process (machines, tools, sandpaper, stains, or finishes). We begin each job with the correct grit to get the job done, not a grit more aggressive than necessary. We do not skip grits of abrasive. And we use our Bona PowerDrive and Lagler Trio to produce the flattest most dust free Floor in the industry. By employing our system, you can be assured that even the roughest floors can look spectacular again, no more of the typical waves and chatter left by other contractors.
Our Sanding System produces a beautiful, fresh surface with negligible wear layer removal that creates a smooth bond between wood and finish that will maximize the lifetime of your wood floor and finish.