Sanding is not only useful but can make all the difference in a woodworking, metal or drywall project. Sanding can be done by hand as well as in tandem with power tools such as electric sanders to create the best finishes on these materials. Sanding by hand works well for woodworking and finishing, especially for giving surfaces a lighter touch. Sanding with power tools helps scrape off material quicker, with the added potency of shaping and leveling wood. It’s also used to prepare metals for a paint job.
Sandpaper for power sanding is sold in sheets, belts and discs. Regardless of which route your application requires you to take—hand-sanding or power-sanding—knowing the differences between the sandpaper grades is key to completing a sanding application. Choose accordingly with our sandpaper grit chart and by following the nuances in grades and material.
The grit of sandpapers is a rating of the size of abrasive materials on the sandpaper. The higher grit number is equivalent to a finer abrasive, which creates smoother surface finishes. Lower grit numbers represent coarser abrasives that scrape off materials much quicker. In the chart below, the grit is measured via both the CAMI (Coated Abrasives Manufacturing Institute) and FEPA (Federation of European Producers of Abrasives) standards, the latter of which is preceded by a “P.” There are two main subdivisions, micro and macro, with many more gradations included.
Micro grits are a class of finer abrasives. They include higher grit numbers. Micro grit-sized sandpapers are commonly used on wood and some on drywall.
|Ultra Fine||Most delicate abrasives||800 or 1000||P1500,
|8.4-12.6 micrometers||Final sanding and polishing thick finishes|
|Super Fine||Slightly wipes away patches/small inconsistencies but not strong enough for removal||400, 500 or 600||P800, P1000 or P1200||15.3 to 23.0 micrometers||Final wood finishing|
|Extra Fine||Slightly less fine and more abrasive than Super Fine||360 or 320||P400, P500 or P600||25.8 to 36.0 micrometers||Initiative methods for wood polishing|
|Very Fine||The least fine of the micro abrasives||240||P240, P280, P320 or P360||40.5 to 58.5 micrometers||Sanding finishes between consecutive coats and drywall and wood|
Macro grits are a class of abrasives that range from medium to coarse sandpaper calibers. They feature mid to low grit numbers. Macro grit-sized sandpapers are commonly used on tougher wood and metals and have a stronger clearance.
|Very Fine||A coarser material than Very Fine under the micro abrasives||150, 180 or 220||P150, P180 or P220||190 to 265 micrometers||Sanding on bare wood|
|Fine||Cannot remove varnish or paint on wood||100 or 120||P100 or P120||115 to 162 micrometers||Preparing wood for finishing, cleaning plaster and removing water stains on wood|
|Medium||Medium to coarse surface texture after sanding||80||P60 or P80||190 to 265 micrometers||Sanding bare wood to prepare it for removing varnish and final finishing|
|Coarse||Has the ability to remove material rapidly||40, 50 or 60||P40 or P50||336 to 425 micrometers||Wiping away a layer of debris or finish with minimal effort|
|Extra Coarse||Quickens the removal of most materials rapidly||24, 30 or 36||P12, P16, P30 or P36||530 to 1815 micrometers||Initial efforts in hardwood floor sanding|
Besides the grits and grades, sandpaper is made out of materials that vary chemically. It can be made from the grains of a natural mineral called garnet, or from synthetic ones like aluminum oxide, alumina-zirconia or silicon carbide. Irrespective of the sandpaper you work with, it must have a strong bond between the sandpaper grit and its backing material. If it doesn’t, the grit and backing material may become separated during use, ruining your application. Backing for sandpaper includes paper, cotton, polyester, rayon, PET film and rubber. Mylar is used as backing for extremely fine grits.
Grit size refers to the specific size of the abrasive grain (36, 60, 120, etc.), while grade is a broader term, with each grade including a range of grits. For example, medium grade includes grit sizes between 80 and 150.
The information contained in this article is intended for general information purposes only and is based on information available as of the initial date of publication. No representation is made that the information or references are complete or remain current. This article is not a substitute for review of current applicable government regulations, industry standards, or other standards specific to your business and/or activities and should not be construed as legal advice or opinion. Readers with specific questions should refer to the applicable standards or consult with an attorney.
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