Follow in the Footsteps of This Experienced Wood Floor Sander

Howard Brickman Headshot
Hf 1004 29

Hf 1004 29

Learn your fundamentals and practice them with a religious zeal, because fundamentals will get you past many of the small things that can occur to mess up a wood floor. In my consulting practice, I look at nothing but failed jobs, and 98 percent of the failures are related to not properly executing fundamentals such as: keeping the floor clean while sanding; using the proper sequence of actions; maintaining control of the environment and physical area in which you are doing work; and monitoring and documenting temperature, relative humidity and moisture content of the job from start to finish. If you are not executing the fundamentals properly, you will have problems, especially when it comes to doing the fancy stuff or custom work.

Knowing the fundamentals goes beyond understanding what grits of paper to use on a floor and following a sanding sequence—it is skillful operation of the machines and tools; knowledge of your materials and surroundings; careful management of the job site and job-site conditions; precise planning; and an understanding of your client's wants and needs regarding the flooring. Looked at that way, sanding and finishing a custom floor is no different from sanding a regular strip floor—it's more a state of mind than it is a variety of flooring. In fact, sometimes sanding and finishing a regular strip floor, where there are particularly high expectations as far as finish and color, can be equally as difficult as the most intricate floor pattern. Whether an installation is simple or complex, it's the sanding and finishing of that floor and how you relate to the customer that really makes or breaks a job.

For Example...

A good example of how to sand and finish a custom wood floor successfully is a job my crew and I did in Brookline, Mass. Counting both the floors that had to be repaired and refinished and the new flooring that was installed, the home included about 4,000 square feet of wood flooring, most of it white oak. The customer was intimately involved in the design and construction of the home, so we saw quite a bit of her at different points in the project. Early on, we discussed everything from wood species to installation and design, color and finish. After the installation was completed to specifications, we left the job site to allow the other finish trades to complete their work. A quick two months after my crew and I had completed both the repair and installation work, we were back in the home, ready to sand and finish. Before we could get on with our work, though, we had to put the floors and the job site in order.

Our focus early on was to remove the floor protection, clear the rooms and floors of any debris or items left by the other trades and determine if there was any damage to our floors that had to be fixed. We discovered four substantial dings and dents that required singleboard replacements, and the footprint of the cabinets had changed, so we had to make a 3 1/2 -inch adjustment to the parallel skirting we had installed in the kitchen. Luckily, the cabinet was larger, and all we had to do was cut the field of the floor back 3 1/2 inches and then adjust the corners and border to match.

Owning the Floor

Once we finished the repairs and brought the floor to the condition it was in just after installation, it was time to take full custody of the premises, making sure that everyone was out of the job site. I explained that, in order to keep the floors clean and ready for my sanding and finishing crew, no other trades would be allowed into our work area without consulting us first.

Walking Orders

With site "ownership" established, we went around the rooms one more time, adding to our job notes anything we felt needed to be discussed with the project manager. Then, it was time for a final walk-through of the job site with the project manager and homeowner.

During the walk-through, we discussed the things that needed to be done before we could begin our sanding and finishing—such as moving the huge Sub-Zero refrigerator out of the way and into place in the kitchen so that it wasn't later dragged across the newly sanded and finished floor. We also discussed the appearance and color of the floor.

At this stage of the project, we usually look for wrong colors in the natural boards. For example, if we had, during a moment of distraction, inadvertently put a dark white oak board next to two of the lightest boards in the floor in a noticeable spot, those boards would need to be replaced. On most jobs with a clear or normal stain color, we make sure that the decision-maker has approved the flooring for color as it was installed. As wood flooring professionals, we understand that there may be considerable variation in the natural color of many of the species and grades of flooring that we install. Clients, however, don't always know this and should be informed of this before a project is started and again as the flooring is installed. For this project, however, we already had decided on a dark stain and finish process—the floors in the living room, dining room and kitchen, as well as the stairs, were to receive a coat of dark aniline dye and a coat of very dark brown stain to create a black look—so we didn't have to worry about the natural color of the boards.

The "E-Word"—Environment

We also went over the proposed schedule and addressed any scheduling concerns, and I explained where any schedule variances could occur. I then brought up the E-word—the environment in the house. We had been monitoring the temperature, relative humidity and moisture content of the subfloor and flooring since before we started the installation, using a monitoring unit that sends the data over the regular phone line to a private Web page where the daily readings are posted. I printed out the last two months of readings and pointed out a two-day period where the temperature in the house dropped to 49 degrees. The project manager explained that the HVAC was being upgraded and had quit working over the weekend, but that they had it running again before the house started to freeze up. The HVAC had been running perfectly for three weeks, and they did not expect any further problems. I requested that they set the HVAC to run at normal temperatures 24 hours a day until several days after the finish was dry to ensure that we had optimum drying conditions.

Final Approvals

With the job site clean and ready, the walk-through complete and the environment stabilized, we did some sample areas of the dye, stain and finish. For these three floors, we did five or six samples of 2 or 3 feet square using the exact same process we were going to use. It took about four days to sand and get the stain and first couple of coats of finish on, but the customer was going to get a good idea of what the floors would look like in the actual rooms, under the actual lighting conditions. We then brought the homeowner back to approve the samples, and I encouraged her to come back and view the samples at night before giving the final go-ahead. It's important to note that the walkthrough and color talks don't have a sequence—one can be before the other. In fact, we might have already had a color talk during installation, but because changes to color can be made up until the stain is actually on the floor, color may be discussed multiple times on the job.

Once the color had been checked and approved, we examined all floors (existing and unfinished) for any additional filling or nail setting that had to be done. Nail setting and filling is an ongoing process. You want to set all the nails and fill all the holes so that once you get to sand, you don't have to deal with too much of that. At this point, we were looking for things that popped up or that were missed during installation. Then, we were finally ready to start sanding.

The First Sanding Round

We started our sanding process in the living room, which was a linear floor. We started by crossing off the floor with the big machine. In our case, this was a belt sander. For our first cut, we ran the machine at 20 to 30 degrees with a 60grit paper. After this first run with the big machine, we cleaned the floor by carefully sweeping with a quality finebristle broom. This is something we do after each step in the sanding process to ensure that no sawdust or debris is left on the surface of the floor. You also should check the wheels for debris and filler. Then, we immediately straightened it out with a 60-grit paper. Since this was an unfinished floor, after the first two cuts with the big machine, the floor was ready for the edger. We went around the perimeter of the room, cutting with 100-grit paper.

Then, we hand-scraped our corners and made the final cut with the big machine. We cut with the grain using 100-grit paper, easing up to our edges to get what we call "rooster tails" off the butt ends of our floor. When you run an edger where the floor runs perpendicular to an end wall, the way you move the edger back and forth creates a wispy, circular scratch in the floor that is anywhere from 10 to 15 inches out from the wall. To remedy that, we feathered into the edges without the big machine, stopping 6 to 8 inches from the wall. This way, it's hard to tell where you pulled the drum up on the big machine, and that gives you a very gradual transition.

Keep It Clean

Remember, a critical element in keeping the surface flat is to keep the floor as clean as possible during the sanding process. This usually means emptying the big machine dust bag before it gets half full and the dust pickup loses suction. Keep in mind that "a clean job is a happy job." Dust collection also helps to keep the floors clean.

We run dust collection on all of our sanding machines except the big machine, but we are careful to keep the bag properly emptied to maintain suction. This makes for a much safer and productive work environment. In the past, the edger and buffer were the major culprits when it came to generating the dust storm, but there have been major improvements in dust collection in the past five to 10 years.

There is no excuse for trashing a job anymore. And, the amount of fine dust that you allow to become airborne is going to impact the quality of the finished job. If the job isn't fairly dust-free by the time you get around to applying the stain and finish, the dust and debris that remain in the finish are going to make you look like a slob. You need to clean up after all of the other trades whether you like it or not. This means cleaning the countertops, windowsills, and, yes, the HVAC outlets commonly known as the "built-in trash receptacles" by all of the other trades. Nothing matches the frustration during the application of the final coat of finish quite as much as a clump of dust that flies off a windowsill onto your applicator and gets spread across a third of the entry hall.

After our final cut with the big machine, we screened the floor with our buffer using an 80-grit screen. As a rule of thumb, you usually should drop back down a grit when going to a screen. For example, after sanding with 100-grit paper, you would drop back to an 80-grit screen, as was done on this job. Then, to get a uniform texture on the surface of the wood, we popped the grain using a sponge applicator dipped in water from a small plastic dish. We then let the floor sit overnight.

The Next Day

The next day, we applied the first coat of stain to the room. The aniline dye comes as a powder, so we had to mix it with warm water at a certain temperature range to make sure that we had a good suspension of the dye in the water. We let the dye cool down, and then we applied it to the surface of our floor using an applicator and wiping off the excess. Because this was an aniline dye, there wasn't a lot of excess to wipe off because it absorbs into the surface pretty quickly. The stain then had to sit overnight. Many times, it only takes an hour or two to stain a room, so we did it at the end of the day so that we didn't have to smell the fumes all day and so that the job site was empty while the stain dried.

We then moved into the kitchen. We followed a similar sanding procedure, crossing off the floor with 60-grit paper at 20 to 30 degrees and straightening out with 60-grit paper. But, because we had a border, we had to be careful not to sand from the main part of the floor onto the border with the big machine, or it would dig into the perpendicular grain and cause dips or scratches. Luckily, because this border was parallel skirting about 14 inches wide, we had long sections of the border where it was actually long enough to run the big machine parallel to the border without having to worry about the big machine running perpendicular to the grain on the adjoining floor surface. We then used the edger to finish the border, using 100-grit paper and overlapping 5 or 6 inches into the main floor. For our final cut, we ran the big machine with 100-grit paper and then used a hard plate around the border. Then, we screened the floor using an 80-grit screen, popped the grain, left the floor overnight and then followed the same process for the first coat of stain as we did in the living room.

One thing of note on this project is that we actually mixed up 3 1/2 to 4 gallons of the dye so that we had enough to do the entire job. Painters call this blocking or batching. This is done to make sure the dye and/or stain is all the same color. So, we maintain our control of the uniformity of the color by making sure it is stirred up properly and that it all comes from the same batch. This also is a smart thing to do when mixing custom stain colors.

After we had a coat of stain on the kitchen, we moved on to the dining room. The dining room was an existing floor that had to be refinished. It was a linear, 5/16 -inch floor that was 2 inches wide and face-nailed with brad-type nails. The prep process for this floor was pretty cumbersome—there were probably 1,500 nails to set and fill. We spent a day just hand-setting and filling and then followed the same process as we did for the living room floor, except that we had to edge the floor twice. We used 60-grit paper on the edger because 100-grit paper tends to load with finish.

Staining, Then Waiting

With the sanding and first coat of dye done on all the floors, we went back to the living room to apply a coat of oilbased stain. We vacuumed the surface of the floor, applied the stain with a rag and wiped off the excess. Then, because it was an oil-based stain, we let the floor sit three days to dry. We followed this same process in the kitchen and dining room, as well.

Once the stain was dry, we vacuumed and tacked the surface of the floor with mineral spirits and applied the first coat of finish. We used an oil-modified urethane that we cut in with brushes and applied with a lambswool applicator. The finish dried overnight, and we came back for the second coat. Between finish coats—and we did three coats in each room—the floors dried and were rubbed down with the buffer. We used a brown/red pad with abrasive strips with a 180- or 240-grit.

We also worked on stairs in the home. The stairs had the same finish on them, and we followed the same finishing process. The sanding process, however, was a little different. We started out with a 60-grit paper on a stair edger and then moved to a 100grit. Then, we used a 60-grit with a palm sander, making the whole surface of the treads uniform in scratch pattern. Finally, we used a 100-grit paper on the palm sander and hand-sanded with 100- or 120-grit around the balusters. It takes five minutes or less to hand-sand a tread, and you get the scratches out so you can't see them. We then worked from the top of the stairs to the bottom when finishing.

Remember, all of the gizmos and fancy new equipment will not save you if: 1) you are not in control of the physical space where you are working; 2) the environmental conditions are not being controlled at the proper temperature and relative humidity; 3) you don't allow sufficient time to properly complete the job; and 4) you are not managing the many small details that combine to define a high-quality job. After all, regardless of the design of the floor, a "custom" job really is more about the expectations of the quality of the end product. Because we kept all of these factors in mind, the floors in the Brookline home met every expectation.

A Note on Edgers

The edger is the most difficult sanding machine to run properly from both a skill and physical perspective. Have an experienced man run the edger, minimizing the use of the edger whenever possible. The edger has a very aggressive and unique circular scratch pattern that is sometimes difficult to remove or blend with the linear pattern of the big machine. And, edgers can create deep scratches that are difficult to sand out, especially with course papers. Here again, try not to put anything coarser than a 40-grit on the edger and then only to skim the built-up old finish off of the floor without putting any deep scratches into the wood. The butt end of the floor (where the ends of the flooring meet the baseboard) is where you have to run the edger on an axis perpendicular to the grain of the wood, which leaves the deepest scratches.


Sanding Tips

1) When starting to sand, begin with only a coarse-enough grit to remove the unevenness, overwood or old finish from the surface of the floor. This should be standard procedure with all sanding jobs. Why remove more material than necessary by starting with too coarse of a grit?

2) The first cut with the big machine establishes how many cuts you must make. Remember not to skip more than one grit. The grits (from coarser to finer) are 16, 20, 24, 30, 36, 40, 50, 60, 80, 100, 120 and 150. We rarely start with anything coarser than 40-grit paper. The very coarse grits can leave deep scratches in the surface, which will require a lot more material to remove. If a floor is in bad shape, we might cut it twice with a 50-grit rather than start with a 36-grit. Of course, with a heavy build-up of finish, you will need to use the more coarse, open, coated paper to keep the paper from becoming clogged with the finish.

3) For consistency, you should have a sanding sequence that you use on every job. We use this sequence:

  • rough cut with big machine
  • rough cut with edger (if required)
  • intermediate cuts with big machine
  • final edge with 100-grit
  • hand-scrape corners
  • multi-disc or hard-plate smaller and cross-sanded areas
  • final cut with big machine (80, 100 or 120 grit), carefully feathering onto the edger marks
  • multi-disc or screen the entire surface, carefully covering every square inch to get a uniform scratch pattern without any visible sanding marks.

4) In areas that are not accessible to the big machine, use the edger to get the surface flat or remove finish.

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