Hardwood Floors April May 2018

AT THE SITE

By Greg Mihaich

Picking the Right Abrasive for the Job

With all of the high-quality equipment we use to sand a wood oor properly, the abrasives are the only component of the entire process that comes into direct contact with the wood. e type and grit of abrasives used on the job are an important consideration for determining how the nal results of the job turn out, and it is important to recognize that each job will likely have di erent abrasive requirements. For starters, storage conditions (temperature and humidity) can a ect the performance of the sandpaper. Maintain “normal” conditions where abrasives are stored (60-80° F and 30-50 percent RH). Abrasives should be stored in original packaging and stored away from potential sources of moisture. Do not store abrasives directly on concrete oors due to the possibility of picking up moisture.

2. The adhesive bond is the binding agent used to adhere the minerals to the backing. These adhesives are designed to withstand the high temperatures and pressure produced in the sanding process. Phenolic resins are typically used for floor sanding applications. 3. The abrasive minerals or grains can be comprised of different man-made materials. The main defining characteristics of abrasive grains are fracturing and friability. Macro-fracturing grains break down into large particles. Micro-fracturing grains break down into small particles. Friability refers to how easily a grain fractures. How the grain fractures dictates product life. The most common minerals used in our industry include:

» AluminumOxide: A blocky shaped grain with sharp edges. Aluminum oxide is a macro- fracturing grain and very friable. It is ideal for low-pressure applications such as intercoat

abrading and orbital sanding. It is sometimes blended with ceramic and zirconia grains in belts and edger discs. » Silicon Carbide: A pointy, very sharp grain that leaves a ne

Mineral photos courtesy of Greg Mihaich

Sandpaper is made up of three general components: the backing, the adhesive bond, and the abrasive mineral (or grain). 1. The backing is the base for the abrasive minerals to be bonded to. In the wood flooring industry, backings are typically made up of paper, cloth, or screen mesh. The type of backing used dictates the intended usage of the abrasive. Lightweight A, B, and C weight papers are used for hand sheets and orbital discs. Mid-weight E and F weight papers are used for edger discs. Heavyweight X and Y weight cotton and polyester cloth are used for belts. Polyester mesh is used for screens.

scratch. Silicon carbide is a macro- fracturing grain and very friable. It is typically used for sanding so woods, some hardwoods, and removal of gummy coatings. Since it is so friable, it dulls quickly and has a short life. » Ceramic Alumina: ere are di erent types of ceramic grains for di erent applications. ey can be long and pointy or very symmetrical in shape. ey are extremely sharp. Ceramic grains

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