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> Sward hardness rocker model c # 891
Sward hardness rocker model c # 891
SWARD HARDNESS ROCKER MODEL C # 891
This instrument is used for the determination of the hardness of organic coatings on the principle that the
amplitude of oscillation of the rocking device decreases more rapidly the softer the surface on which the test is
conducted. Its performance is sensitive to the surface condition of the coating or test piece and may be
influenced by the thickness of the coating and the nature of the substrate.
It is important that the test piece is level and free from movement or vibration and the test is carried out in a
controlled draught free atmosphere. The test procedure is fully described in ASTM D2134.
The levelling table with the test plates is levelled carefully and the surface of the glass test plate thoroughly
cleaned. The underside rings of the rocker should be examined critically and cleaned with a suitable solvent to
1. Place the rocker carefully into the test surface, roll the instrument to the right until
IMPORTANT: ensure that NO undue pressure is applied to the rocker.
2. Release the rocker START counting the number of rocks (complete oscillations)
when the LEFT-HAND bubbles just disappears.
3. STOP the count when the right-hand bubble just disappears.
