Hardwood Floors June/July 2018

In the mid-1900s, metal complex dyes were developed, which resulted in the benefit of a further increase of lightfastness, but, still all dyes fade more than pigments (we will address this later in this article). Depending on the formulation, dyes may be soluble in oils, alcohol, or water. For dying wood flooring on a job site, we typically don’t use alcohol dye as it dries instantly, which is not very practical. So, we use mostly water- soluble dyes. Dyes are available in powder form or in a solution of alcohol, so both are soluble in water. Due to the strong coloring strength of dye, a small amount of powder/concentrate makes a large batch of dye. Dye penetrates deep and bonds to the cellulose of wood, even the densest wood species will absorb dye. Its application is challenging if one has never used it before and typically a second application is applied to intensify and even out a color and to blend in lap marks from the first application. But, dye dissolves in the solvent it was mixed in (in our case water), so, therefore, it can also dissolve and migrate out of wood when exposed to water. This means we need to protect it before finishing it. Also, as mentioned before, we know that dyes are not very lightfast either, so we must protect the dye from light somehow. Remember that pigment in stain is more lightfast. This is the reason why a dyed floor needs to be completed with a good quality oil-based floor stain before applying a finishing product; an oil-based stain is selected for this purpose. (Note: the dry dyed wood tone is completely different from the finish coated dyed floor. Make samples to pin down the final color before applying to the job site). CHEMICAL REACTIVE STAINS Chemical reactive stains react with tannic acid present in wood species. Therefore they are most effective on wood species that contain a high amount of tannic acid. Examples of such species include: white oak, walnut, Brazilian cherry, black (American) cherry, and mahogany. The most well-known reactive stain terminology here in the U.S. you may have heard of is “fumed oak.”This was a treatment that was first used during the Arts and Crafts movement and by Gustav Stickley in the early 1900s in the Craftsman period for Mission style furniture by exposing white oak to the vapor of anhydrous ammonia in a sealed chamber (this chemical process is highly poisonous). This process produces a beautiful aged brown color (throughout the entire thickness of a fumed board). Europeans were already using this process in the late 1800s after accidental discovery when it was noticed that installed oak boards and beams in horse stables turned color (from the ammonia present in horse urine). Fumed oak in the EU is referred to as “smoked oak.”This process is still used in controlled environments, but due to the dangers, is not used on site-finished floors.