Hardwood Floors April/May 2019

AT THE SITE Can the Floor Withstand a Resand? (Continued) I

o en designed for intercoat abrasion or with the rst sanding on factory- nished oors. High- abrasion nishes, such as those used on factory- nished oors, can be very di cult to sand. High-abrasion nishes respond be er by using a ceramic red ne-grit (80-grit or ner) abrasive as the rst grit used. is rst cut is made to break down the surface nish, not to remove material or a en the oor. Choosing the proper grit sequence for every situation is nearly impossible to de ne as there are a wide variety of circumstances that may dictate many di erent scenarios. e abrasive grade (or grit) provides information about the size of the mineral used on the paper. e grit number directly corresponds with the number and size of minerals per inch. e larger the number, the smaller the mineral. Choosing the appropriate grit sequence for the job will dictate the process to achieve the necessary results.

Finer grits require less-pressure se ings on the bigmachine; coarser grits require heavier-pressure se ings.

oor will result in uneven bevels. In the case of a micro bevel product, it is possible that the bevel will be eliminated. e sanding process may require extra cuts in order to eliminate these eased edges. When maintaining the beveled edges, carefully clean and/or scrape the bevels (be careful not to damage the face of the board). Caution when sanding, and a lot of hand work/detail work are also necessary when addressing bevels during a resand. When the ooring material allows (su cient wear layer), bevels may be recreated in the oor by using hand scrapers, hand planes, block planes, chisels, spokeshaves, routers with a V-grooving bit, or other specialty grooving tools. In addition, make the customer aware that sanding a beveled-edge product will change the pro le of the bevel and the look of the oor. Choose the right abrasive – e grit chosen for the initial sanding will be determined by several conditions including existing coatings, the degree of unevenness, species, and overall condition of the ooring. For factory- nished ooring, the initial sanding of the wood oor should be with the nest grit abrasive possible to remove the existing coatings. Di erent types of oor coatings respond di erently to di erent types of minerals used with the abrasives. Aluminum oxide minerals are blocky, cubic-shaped minerals. ese minerals typically fracture into larger pieces, maintaining sharp edges. ey are commonly used with ne and extra- ne abrasives

GRIT

High/More

16 24 36 40 50 60 80

Sanding Pressure

100 120

Low/Less

For the rst cut on a factory- nished oor, you rst need to determine the type of nish you will be removing. enmake an abrasive selection. When resanding a dark-stained or white-stained oor and changing color, the oor can exhibit residual stain in the so grain and cracks, whichmay require a more aggressive rst cut to remove the previous color. Again, keep wear layer thickness and bevels inmind whenmore aggressive sanding is necessary. Subsequent cuts are then followed by a coarser grit to begin the upward grit progression to remove the remaining surface nishes and to begin a ening the oor as necessary. Skip nomore than one grit fromthe abrasive used in the second cut. All following cuts remove the scratches created by the prior cuts, leaving shallower scratches that should result in a surface that appears smooth. e nal sanding processes involve examination of visible edger and sander imperfections. esemust be removed by hand before the nal sanding stages.When using handheld

AB SIVE GUIDE

ABRASIVE GRADES (GRIT)

PAPER TYPE

Open Coat

12, 16, 20, 24

Coarse

30, 36, 40

Medium

50, 60

Fine

80, 100

120, 150, 180, 220, 240, 320

Extra Fine

Followproper sanding technique– Before sanding, the oor should be vacuumed and evaluated carefully. Drumpressure se ings should coincidewith the abrasive choice.

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