Hardwood Floors April May 2018

AT THE SITE

True Grit (Continued)

e grit used on this rst sanding step should be the nest grit possible to achieve everything previously mentioned, while minimizing the scratches being placed into the ooring surface. In most cases, you should never skip more than one grit abrasive when progressing upward in sequence.

ABRASIVE GUIDE

ABRASIVE GRADES (GRIT)

PAPER TYPE

12 16

Here is a chart showing paper type and abrasive grades.

Open Coat

20 24 30 36 40 50 60

Coarse

Load the sanding machine with the proper sequence of sandpaper. Skip no more than one grit from the abrasive used in the rst cut. e second cut abrasive removes the deep scratches created by the rst cut. Skip no more than one grit from the abrasive used in the second cut. e third cut removes the scratches created by the second cut, leaving shallower scratches that should result in a surface that appears smooth. e nal sanding sequence must be ne-grit paper or higher. When the nal sanding sequence with the belt/drum sander ends at a medium grit, use of multi-head/planetary sanders must be used to follow the abrasive grit sequence to ne or extra- ne grits to achieve the desired end result. Do not skip any grits when employing this nal sanding process. It is also important to use the same grit in the nal sanding process with all of the tools (edger, big machine, orbital), and then blend with a bu er or multi-head sander. TYPICAL GRIT SEQUENCE e initial sanding of the wood oor should be with the nest grit abrasive possible to a en the oor and/or remove existing coatings. Big machine drum pressure se ings should coincide with the abrasive choice. Finer grits require less pressure se ings on the big machine; coarser grits require heavier pressure se ings. REMEMBER: • Start with the nest grit paper that will remove existing coatings and a en the oor. • Do not skip more than one grit. • It is also recommended to not skip any grits in the sanding sequence when you get to the extra ne abrasive selections, or with extremely dense oors such as end-grain, strand-woven products, or some imported species.

Medium

80 100 120 150 180 220 240 320

Fine

Extra Fine

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