The powdered chalk is available at the hardware store and is sold in plastic bottles used for filling the tools that are used in setting a chalk line. I use the blue powder and mix it with water. Brush it on, but be careful not to make it to thick otherwise you'll get false readings. Tap the pinblock and then rebrush the existing chalk. Brush on more chalk everyother time or when it is needed. David Porter St. Louis, MO
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