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TIP: Testing Your Finish for Hardness

Jun 29, 2016 | Expert's Corner | 0 comments

You can use architect’s pencils to test for finish hardness (scratch resistance). The lead in these pencils is rated from about 6 or 7B, the softest, to 6 or 7H, the hardest. HB is in the middle. You don’t need to buy all these pencils, just the middle five or six, because most finishes will test to one of these.

To prepare the pencils sharpen them with a pocketknife, not a pencil sharpener. Then ground the tip of the lead perpendicular to the length of the pencil on fine sandpaper, or regular paper if the lead is close to flat. You want the 90-degree angle at the tip of the lead to be sharp.

To perform the test, hold the pencil as if writing and push it forward into the finish, as shown in the accompanying picture. You don’t need to use much pressure, but it’s important to use about the same pressure with each pencil and on each finish you are testing to get an accurate result.

Begin with one of the softer-lead pencils and work through the hardness until you get to one that leaves a cut mark in the finish. This is the rating for that finish.

You can easily tell if one type of finish provides more scratch resistance than another.