Oh, So you do that too...

The title of this blog may seem a little odd, but it serves a purpose. Sometimes there is a little bit of confusion to the services my company offers in the world of wood flooring in Portland. My portfolio on the website could possibly lead people to believe that our work is only high end and custom work. The truth is that 90% of the hardwood floor installations we undertake are adding new flooring to an existing wood floor and refinishing the whole floor. I will walk you through this with a couple of step by step photos. In the first photo is where the floor ended after a wall was taken out in a remodel by my friends at Envi Construction. In the next photo, you can see where we removed a selected number of boards so that we may integrate, in a random pattern, new flooring. The goal we seek to accomplish is making the new floor and the old floor look harmonious in every way. Afterwards, new matching flooring was installed and sanded and finished for a contiguous appearance. There are a couple of tricks to ensuring a proper appearance that involve grading and specifying the mill providing the material. Depending on the mill and the region of production some flooring (particularly red and white oak) can be quite variable in the tones. This difference doesn't become evident until sanding, so specifying product relies on a particular attention to detail and experience.

Hardwood finish and adhesion, the overlooked but critical factors

The tremendous range of hardwood floor finishes available these days has become almost exhausting to keep pace with any more. In the previous blogs we have discussed wood floor finish options and pro and cons. This blog has less to do with actual chemistry and understanding mechanisms of adhesion.

There are pretty much two ways by which hardwood floor finishes adhere to a floor, chemical or mechanical bonding. Chemically bonded finishes integrate into previous layers and essentially fuse into one layer of finish. Acid curing "Swedish" finishes will chemically bond to a wood floor and merge into one finish layer. The significant advantage of this type of bond is that it is virtually impossible for the finish to have adhesion problems to a wood floor regardless of the final burnishing steps or the species of the hardwood. Some species of hardwood contain a high content of oil and sometimes silica and this may create potential adhesion problems for a finish.

The second form of bonding of finish to a wood floor is a mechanical bond. A mechanical bond of a finish requires a roughed up surface so that finish can literally fall into the texture of that surface and "grab" the substrate. The layers of finish in a mechanically bonded system are much more sensitive to compatibility as they are applied in succession. For example, if you stain a wood floor with a penetrating stain, and then apply a weakly bonding quick dry oil sealer, followed by coats of waterborne urethane, there is a real chance for the finish layers to be torn off the floor following application of tape or some other sticky substrate. I have witnessed this firsthand and received many phone calls from distressed colleagues.

The final finishing grit of the sanding process can also affect adhesion. I know that there are sanding machines present that rotate with such significant speed that they may close down the grain of the hardwood floor at certain sandpaper grits so that a mechanically bonded finish will have problems sticking to the floor. In this case I recommend re-opening the grain by wetting or "water-popping" the floor.

A final and overlooked factor affecting finish adhesion occurs during abrasion of a finish coat layer in order to accept a new finish coat. The abrasives used to abrade the floor will typically become dull within a suggested square footage for usage. If a contractor continues to abrade the finish layer with a dull abrasive, the surface may again become too slick for the new finish layer to hold on. The result is that the finish will peel off the floor in big sheets.

Although this blog may not be particularly intriguing to all, it may serve as a reminder that there are sometimes questions to ask your contractor that go well beyond the price of the job.

White Lines Syndrome

The latest trend in wood flooring has definitely been for darker floors and wider boards. Exotic wood flooring has also seen growth in market share. One of the unspoken problems is that when seasonal movement occurs within the boards of the floor some finishes can actually become stretched out during this process and they leave a white line down the seam of the boards. This problem is particularly bad with waterbased finishes that have come to dominate the market with low VOC laws emerging in many states. Waterborne finishes lay across the floor and essentially act as a hardened sheet of plastic that resists traffic.

Using an acid curing conversion varnish or true "Swedish" finish is the best option to prevent this problem. This is because the acid curing finishes will truly break their bond at the edge of each board and stick to the edges of that board during seasonal movement.

If you are planning a flooring project that requires wider boards, dark stain, or both I recommend thoroughly discussing the project with your contractor to prevent this problem. In fact there is so little published information for this problem because the industry doesn't want you to know that there is a dark side to new technology. When white lines occur across your wood floor they almost always require a full refinish to remove and that is never a fun option for your time. If you would like more information please contact us for a PDF of the problem.