The Pencil Hardness Gauge is practical for use in the laboratory, or the production line, or in the field to assess quantitatively the rigidity or firmness (elastic modulus) of organic coatings applied to rigid substrates such as metal. Hardness values may define requirements for particular coatings applications, or may be used to evaluate state-of-cure or aging of a coating.
In this test, pencil leads of increasing hardness values are forced against a coated surface in a precisely defined manner until one lead mars the surface. Surface hardness is defined by the hardest pencil grade which just fails to mar the painted surface.
The gauge is composed of a set of eight mechanical drawing lead holders (pencils) permanently mounted in a circular array on a plastic cylinder. A small metal tube through the center of the cylinder provides storage for spare leads and is a guide for positioning pencils for a test. Alternate pencils in the assembly point in opposite directions, so that in either direction four pencil tips define a square around a guide tube, and each pencil may be precisely positioned instantly to perform a test. Pencil positions are identified by numbers 1 to 8 on the plastic holder.
The Pencil Hardness Gauge is unique only by the fact that it provides a compact single unit for performing this test rather than a set of easily lost individual pencils. The importance of this advantage should not be discounted, especially when several individuals may be working with a single instrument. Leads supplied with the unit, softest to hardest, are as follows: 6B, 5B, 4B, 3B, 2B, B, HB, F, H, 2H, 3H, 4H, 5H, 6H.
The leads are supplied in a holder that identifies each lead (individual leads may come without identification, or the identification mark may be difficult to read). Choosing and installing the eight leads most appropriate to the surface(s) being tested will allow the most commonly used leads to be always “at the ready.”
Five small circular pieces of 400 grit carborundum paper mounted on a plastic dressing disk are provided to facilitate dressing the lead points while they are in place in the gauge. The Pencil Hardness Gauge is supplied in a padded vinyl case. |
Prices listed in US dollars for domestic shipments within US, Canada, & Mexico only 