Hardwood Floors June/July 2024

AT THE SITE The Effects of Chemical/Reactive Treatments on Wood Flooring (Continued)

When the hydrogen peroxide component is mixed in, or applied over the sodium hydroxide component, it creates sodium hydroperoxide, which is very aggressive and effectively lightens and removes the natural color of the wood on/in the wood's surface. W co a h

As mentioned before, a controlled single bleach application can lightly damage the wood’s lignin and cellulose fibers, PHOTOS COURTESY OF NWFA

Most of the time, a single chemical application may not do excessive harm or damage to the wood. However, with bleach (both single-step or two-part bleaching), h

but usually, this is not serious enough to cause finishing problems. However, repeated applications of bleach will result in too much weakening of the surface fibers and may leave a weakened base for any finishing system to be applied to. Let’s look at reactive stains: These products typically do not weaken the wood’s lignin and cellulose enough to cause a problem. Reactive stains provide wonderfully aged/rustic colors to a wood species that contains enough tannins. However, the colorfastness of reactive stains often is not very good, and many will experience fading colors with exposure to light. Some fade severely, some less severely, and fading may present itself quickly or slower over time. This fading issue means that the reproducibility of the original color is sketchy at best. So, that would be a serious issue when repairs, touchups, and additions need to be done down the road. What it boils down to with any chemical reactive, is that most wood finish manufacturers will not recommend or endorse the application of reactive treatments before applying their wood finish. This is true for bleaches, and homemade chemical reactive brews. If one plans to apply a different product than what is recommended or manufactured by a finish manufacturer, it is the individual’s responsibility to test for compatibility with the wood finishing product of choice. And know that you likely won’t have support from the finish manufacturer if there were a failure. To avoid potential problems, it often is a safer (and smarter) choice to follow the recommendations of the manufacturer of the selected wood finish.

repeated applications will break down the lignin that holds the cellulose fibers of the wood together. Consequently, this will weaken the wood structure, which can result in a layer of weak/loose fibers on the

surface of the wood that may affect the finishing system you plan to apply. Wood’s natural pH level is slightly acidic/ near neutral, and the application of liquid household bleach shifts the wood surface to a basic/alkaline pH level, which can affect the applied wood finish. Two-part bleach is made of hydrogen peroxide and sodium hydroxide. With this type of wood bleach, the sodium hydroxide effectively degrades and dissolves lignin (up to 90 to 95 percent of its content in the wood surface), and it can also decompose wood carbohydrates, mainly hemicelluloses.

Johannes Boonstra is senior technical manager for Rubio Monocoat USA. He can be reached at johannes@rubiomonocoatusa.com.

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