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Green Streaks
I work in a red oak market, and last week I installed my first white oak floor. Once I coated it, it looked streaky and had a greenish color to it. Why?
Todd McDonald, eastern sales manager for wood flooring manufacturer W.D. Flooring, answers:
This is due to the tannins in white oak. The tannins in the wood react with the urethane (it can happen with any kind of finish), causing these greenish or brown spots.
To help eliminate this, seal the floor with a neutral stain and then apply the finish very evenly. It's the uneven spots where the finish collects and pulls more tannin out of the wood, making areas that look darker.
White oak has a naturally green cast. If the customer objects to this color, you can either stain the floor a different color or choose a different species.
Mix and Match?
I've been trying a few different brands of poly, and now I have partial cans left of several types of finish. Is it OK to combine them? They all look pretty much the same.
Bill Costello, account manager for finish and stain manufacturer Dura Seal, answers:
Is the risk worth it? You might get away with it, but you could also end up with a big mess. You might have differences in sheen throughout the floor, or you could have uneven wear because of mixing a superior product with an inferior product. Different products have different spread rates, so you could have problems with the mil thickness on the floor, and the finish could dry too slowly or too quickly. Mixing different solvents could also lead to problems with curing.
You always need to think about what would happen if you end up with a problem on that job. If you've been mixing different types of finish, who are you going to call when you run into trouble? That's why it's so important to follow the manufacturer's directions for the product you're using and not experiment when you're on the job.
Trowel Tips
What trowel size and configuration do I need when I use moisture-cure adhesive to install my hardwood flooring?
Robert McNamara, national sales and marketing manager for adhesive manufacturer Bostik Inc., answers:
Just like the old real estate adage, "Location! Location! Location!", when using a moisture-cure urethane adhesive for the installation of hardwood flooring, the important thing is "Coverage! Coverage! Coverage!" Unlike some adhesives for which trowel size and configuration might be designed to balance or control flash, open time and/or working time, moisture-cure urethane trowels take only one factor into consideration: How much adhesive is required to make adequate contact between the hardwood flooring and the substrate, i.e. coverage?
Generally speaking, the thicker and/or wider the hardwood flooring, the more adhesive is required to achieve adequate transfer/contact of the adhesive. Therefore, the notches go from smaller to larger. Trowel notch sizes are suggested to maximize the coverage of adhesive. The installer should periodically check the coverage of adhesive during installation. Uneven subflooring may require the use of either a leveling/patching material, or a larger notched trowel for proper coverage of adhesive.
As always, refer to the adhesive label directions for the recommended trowel and required coverage for the size and type of flooring being installed. When in doubt, call your adhesive manufacturer.
Cleaning Clarity
Can I use mineral spirits to clean a hardwood floor? Will they leave a haze?
Bill Jauernig, sales manager at finish manufacturer PoloPlaz, answers:
There are two ways to look at that question—a contractor using mineral spirits to clean between coats, or a homeowner using mineral spirits to do daily maintenance.
If you are a contractor using mineral spirits to tack between coats, make sure mineral spirits are recommended for the type of finish you are using. They are most often used with poly. Also make sure you use "100 percent virgin mineral spirits." Many big-box stores offer recycled mineral spirits. Last year I saw a large, brand-new college gym floor fisheye because 1 gallon of recycled mineral spirits was contaminated with oil residue. Mineral spirits that are 100 percent virgin will not leave a haze on the floor; they are completely clear and very low-odor.
All finish manufacturers make hardwood floor cleaners for use by the homeowner; mineral spirits are not recommended. The key is that you do not want your cleaner to leave a residue on the floor. When in doubt, spray some of your cleaner on a window, let it dry and see if it leaves a residue. Most finish manufacturers also make an aggressive monthly cleaner for commercial applications.
Trick of the Trade: Troubling Tear-outs
Although it isn’t recommended by buffer or abrasives manufacturers, many contractors attach two pieces of abrasive discs under a hard-plate because they find that otherwise the torque of the buffer tends to rip the paper. Here’s an easy way to avoid the abrasive tearing without using two layers of abrasives: simply apply some pieces of blue tape around the center of the abrasive disc as shown.