Acid Staining a Problem Floor

What are we going to do with this mess? The owner wants the beautiful floor he's seen in magazines, but given this slab's condition, there's no

COLOR COMMENTARY

In the summer of 2004, the owner of a proposed tanning salon asked me to provide a bid for decorative staining of a 2000 ft^sup 2^ (190 m^sup 2^) floor. The owner wanted a one-color (antique amber) floor with a sunburst logo added near the sales counter. He had seen our work on the Internet, visited a few of our previous installations, liked what he saw, and awarded us the contract. The salon was to be located in a strip mall and was slated to open in early January of 2005. Even though the slab would be placed by another subcontractor, I assumed there would be few, if any, problems.

At the time, my assumption seemed to be well-founded. There was plenty of lead time, so I had spoken to the general contractor's construction manager well before the slab was placed. He assured me that his company had done acid-stain projects before and that he and his staff knew what measures were needed to ensure success. Based on this, I was confident that I would walk onto the job site to find a perfect candidate for staining. What I didn't know, however, was that the general contractor had actually done only one other acid-stain job. Because it had turned out pretty well, he mistakenly believed that his staff had a firm handle on the process.

About 3 weeks before we were scheduled to stain, the salon owner called me to confirm the schedule. I asked him some questions about the site and was pleased with his initial answers. Yes, the slab had been finished and given time to cure. Yes, the drywall was hung, finished, and painted. Yes, the lights were installed and working, and yes, we had a place to attach our water hose. It sounded like we were all set to go. When I asked him about the cleanliness of the slab though, I began to worry. "It's pretty clean," he said, "because we laid plastic over it to protect it during construction." When I told him the plastic was likely to have discolored the slab, he cheerfully gave me the really bad news: "Well, we didn't put it over the whole slab. We only put plastic down in some spots."

A DISCOLORATION PROBLEM COMPOUNDED

My problem-free project had now turned into a recovery operation-I knew that there was sure to be a significant color variation between the covered and uncovered portions of the slab (see sidebar).

During our contract negotiations, I had told the owner that he could save some money if the floor was very clean when we showed up to stain. When I got to the job site, he was dutifully cleaning the floor with a rented floor scrubber. With every pass of the floor machine, however, it became clear that we had major challenges ahead of us. Areas that had been covered with plastic were obviously visible and included part, but not all, of the area designated for the sunburst logo. To make matters worse, the logo area was also bisected by contraction joints.

Further, each pass of the scrubber revealed more footprints left in the slab by finishers (Fig. 1). Even worse, the cleaning revealed an area around the edge that had been finished using a hand-held trowel and water as a finishing aid. A trowel had even been used to squeegee excess water from the slab, producing arcs of light-colored concrete slurry surrounded by much darker concrete. Finally, we could see that some areas of the slab had been burnished, while other areas had been lightly finished.

After I saw the problems, I gave the salon owner the bad news. I began by explaining the effects of different curing methods and pointing out the areas in his slab that had been affected. I then showed him photos of other acid-stained floors we had done-photos used to give clients a realistic view of the unpredictability of acid stain. The photos dramatically depict several floors that were cured using different methods and then treated with the same brand and color of stain. Figure 2 shows typical examples.

Next, I showed him the footprints and other slab imperfections, and explained that acid stain wouldn't hide any of them (in fact, quite the opposite will happen-stain is translucent and can actually highlight imperfections). Because it would accentuate mistakes, attempting to use a single color would compound our problems.

The owner was upset because the walls had already been painted a color that would have complemented the proposed stain color, and his rugs and fixtures had already been purchased. Although application of a microtopping over the entire slab would have given us a clean slate to work with, neither the budget nor the schedule would allow it. We were stuck with a substandard slab. Fortunately, the owner was eager for suggestions, and I was able to propose a solution.

CELEBRATE THE FLAWS

We had to determine what would look good and yet hide the slab's defects as much as possible. I pitched the idea of a floor that was scored in random geometric shapes, full of arcs and lines. I would place these score lines on the perimeters of the area covered by plastic, and in other "bad" areas. Each section delineated in this fashion would be stained a different color. The random jumble of color would help to conceal the bad areas in the floor. Ideally, customers' eyes would quickly move around the space, taking in all the different areas. Their gaze would never stay in one place long enough to see a defect.

The sunburst logo was another matter. To allow it to work within the space, we had to make it a bit smaller than was originally planned, and move it closer to the reception desk. These adjustments effectively removed it from the problem areas in the slab. After discussing our concerns and choosing several complementary colors, the owner agreed with my plans and we proceeded with the scoring and staining process.

The only minor glitch in our normal staining routine was that the salon still had no working electrical outlets. We had to work with temporary power from the far corner of the space next door. This would normally be fine, except that the floor buffer we rented pulled too many amps to be run off of a normal extension cord. We bought a very expensive 10-gauge cord and began the recovery.

CHOOSING THE SEALER

After staining and cleaning the floor, it looked like we were finally in the clear. That's when another problem arose. Because the tanning salon was flanked by other stores in the mall, we couldn't use our normal solventbased acrylic sealer. I prefer this type of sealer because it gives the acid stain a deep, rich look and is easy to apply.

Unfortunately, solvent-based sealers also produce fumes. Even if we used large exhaust fans, the fumes would be so intense that they could cause problems for the neighboring businesses. In fact, I found that this was exactly what happened on the general contractor's previous stain job. The previous job was next door to a bakery. Fumes from the sealer had ruined all the baked goods and uncooked dough in the bakery. This was an expensive mistake that I had no intention of repeating.

Because we couldn't risk using the solvent-based sealer, we decided on a water-based acrylic and several coats of floor finish-a mop-on water-based acrylicpolyurethane blend that's used to maintain the shine on floors of big-box retail stores. This combination effectively sealed the floor and enhanced the stain, but gave a completely different look to the finished product. It looked good, but lighter and with less intensity than would have been obtained if we had used a solvent-based sealer. To enhance the shine, we buffed the final coat of floor finish with a high-speed buffer. When we had finished, all of the defects including footprints were still visible but weren't nearly as noticeable.

With a little creativity and an open-minded owner, the floor turned out well (Fig. 3).

Selected for reader interest by the editors.