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Standard: |
TAPPI |
Method: |
TAPPI T 459 |
Title: |
Surface strength of paper (wax pick test) |
TAPPI T 459, applicable to uncoated and coated papers, is designed to measure the surface strength of paper or its resistance to picking. It is not applicable to loosely felted papers such as blotters or roofing felts, nor to papers containing materials that soften with heat such as waxes or latex type additives. Light weight papers that lack stiffness may slip under the block during the wax removal step are not suitable for testing by this procedure.
In this test, calibrated sealing waxes with increasing adhesive power are pulled from the surface of the specimens. The highest number of the wax in the series which does not disturb the surface of the paper is the numerical rating of the pick.
Many printing and converting operations require the surfaces of the paper to have sufficient z-direction strength to give satisfactory results. Since no absolute values are obtained with this method, test results should be correlated with actual performance of the material during the subsequent coating, converting, printing or packaging operation.
For coated paper, where a significant portion of the casein or starch coating adhesive has been replaced with a thermoplastic resin, there is very little, if any, correlation between printing press performance and wax test results. The molten wax forms a stronger bond with the coating containing thermoplastic resin and the resulting pick causes the paper to appear weak, when in fact it is not.
For those sheets containing latex and similar substances, a more direct method employing the actual medium to be applied is recommended.
Please note:
SGS-IPS cannot sell or otherwise provide standards, specifications, or test procedures to third parties.