By the Lägler Team
A goal for every contractor’s business should be to minimize effort and time on-site while maximizing quality results and profits. Wood floor sanding is hard work, but that doesn’t
mean it can’t be smart work too.
With a few smart changes to conventional wisdom, hard work can become easier, and it can produce better results. The keys to success lie in the mix of sanding machines, sanding angles, abrasives, and grit sequences used on the job.
Conventional vs. New-School Sanding Methods
Maximum flatness should be the focus on most traditional sand jobs. The quality of machines a contractor uses matters, but sanding machines no more make a floor than a camera makes a photograph or a race car wins a race. The person using the right machines for the job, and with the proper knowledge, skill, and touch, is the real difference maker.
Conventional sanding methods mean using a big machine and edger. A buffer sometimes is used for fine sanding. With this method, the big machine is used for sanding 90 percent of a room’s field, and it is where 75 percent of the sanding time is spent. The edger does the rest of the heavy lifting.
The newer technology in sanding equipment includes the introduction of a multidisc sander to take flatness to a new level. The multidisc can be used for fine sanding but, unlike a buffer, packs enough bite to carry some of the big machine and edger’s workloads too.
Using a multidisc sander shifts how much energy and time a sanding professional spends on each machine. It accounts for 40 percent of sanding time on a typical job. It reduces the time spent on a big machine by 33 percent and time spent on an edger by 60 percent. That leads to less wear and tear on the body of the professional.
A multidisc can be run in all directions. It reduces the risk of common issues like chatter and dishout. It also handles multispecies floors much better.
The industry’s leading craftsmen are turning to the multidisc as a game-changer, a machine they can use to set their floors apart from their competition’s.
Know Your Angle
The greatest efficiency comes from doing a job right the first time, and the cut of your angle is one of the most important aspects of floor sanding. The purpose of the first cut is to flatten the floor as much as possible and, in the case of a previously finished floor, to remove old finish and stain.
For strip and plank floors, the first cut with the big machine should be at a minimum 7- to 15-degree angle to the length of the boards, using the finest grit possible that will flatten the floor (Fig. 1). More aggressive angles (up to 45 degrees) may be necessary to achieve a flat surface in extreme cases. Wider-plank floors, excessive overwood/underwood (exceeding 1/8”), or uneven flooring systems may benefit from a steeper angle on the first cut. Subsequent cuts should be parallel to the length of the boards (Fig. 2).
In cases of permanent cupped floors, it is recommended that the big machine’s first cut follows directly in line with the board lengths before cutting at a 7- to 15- degree angle (Fig. 3). Once the large height differences have been eliminated, the floorboards can be sanded as described earlier.
Certain subfloors can lead to swing of the floor covering. Waves and depressions can form at uniform intervals if a drum or belt sanding machine is used in this case. In order to prevent this problem with conventional methods, the final sanding step has to be made on lengthwise-laid wood flooring at a small angle to the woods’ grain direction.
For parquet floors and other laying patterns with the same sanding direction, the sanding processes for presanding and fine sanding should be carried out at a 45-degree angle to the wood’s grain direction for the parquet types and layout patterns shown in Fig. 4. This prevents gouging/soft-grain dishout and will allow one to flatten the floor easier and faster.
Quality Abrasives Are Unsung Heroes
Quality abrasives are crucial role players on any sanding job. If the abrasives are not up to standard, the sanding results also will be less satisfying than expected, no matter the quality of machines being used.
The materials used in making abrasives affect sanding rates and how many square feet of life a professional gets out of them. Inexpensively produced abrasives have a shorter service life and need more frequent changing. The minerals used
in some abrasives do not perform as aggressively as others, leading to more time spent in the sanding process.
Synthetic blends are primarily used in today’s abrasives. They offer higher temperature stability, higher abrasion resistance, and better adhesion to the abrasive grit and underlayment than previous bindings.
Zirconia and ceramic abrasives offer advantages compared to silicon carbide and aluminum oxide (corundum) abrasives in some sanding scenarios.
Ceramic and zirconia have higher sanding rates and longer service lives, which equal less frequent changing. Their longer service life requires that less inventory be kept on hand and less storage space be used in the trailer, van, or shop.
Proper Grit Sequence Saves Time & Money
Start a sanding job with as coarse a grit as necessary, but as fine a grit as possible. It’s important to correctly choose the starting grit and to follow the correct grit sequence, or lost time and money will add up while trying to correct sanding mistakes.
Coarse abrasives are more expensive than fine abrasives. For floors that require an exceptionally coarse start, such as 16 or 24 grit, save money by using abrasives with less expensive minerals. Use silicon carbide sanding discs on the edger, multidisc, and buffer, and aluminum oxide belts on the big machine.
Save higher-quality abrasives (zirconia) for intermediate sanding steps. These are from grits 36 to 80 on the big machine and as high as 150 on the edger and multidisc. Silicon carbide sanding screens work well on a multidisc sander and buffer, starting at 60 grit.
No more than one grit should be skipped when using a big machine or edger. When fine sanding with a multidisc sander, do not skip any grit numbers. Fine grits remove a low volume of wood material from the previous sanding step, and a skipped grit leaves marks too coarse to be removed adequately.
Correct selection of the grit sequence is even more important for oiled surfaces than for finished floors. That’s especially worth paying attention to since, in recent years, natural oils have become more popular with homeowners. Homeowners also are showing increasing interest in interior design and open-space floorplans that allow larger amounts of natural light.
That highlights the need for sanding professionals who can produce the flattest, most flawless floors. Being capable of producing top-tier results while minimizing energy, time, and cost of materials on the job is essential to a contractor’s success.