Machine-direction grammage variation measurement (gravimetric method)

This procedure can be used to determine the short term machine-direction variation in mass per unit area. These variations can be caused by defects in the stock approach system, headbox, or consistency control. This test method is not intended to identify the source of the variations, but rather to quantify them. The method has particular application to acceptance testing of both the papermaking process and the product.

This test is laborious, but it is reliable and accurate. It requires cutting out samples, weighing samples, and data evaluation.

The general procedures outlined in TAPPI T 410 “Grammage of Paper and Paperboard (Weight per Unit Area)” and in TAPPI T 402 “Standard Conditioning and Testing Atmospheres for Paper, Board, Pulp Handsheets, and Related Products,” are used as basic references for this method. TAPPI T 545 “Cross-Machine Grammage Profile Measurement (Gravimetric Method)” is the counterpart to this method for the cross-machine evaluation.