Forming handsheets for reflectance testing of pulp (Büchner funnel procedure) Test Method TAPPI/ANSI T 218 sp-18
This practice describes the procedure using a Büchner funnel for preparing specimen sheets for reflectance testing of bleached or unbleached pulp whose fibers are readily dispersed in water. The sheets are made at a pH of 6.5 ± 0.5. This practice permits the preparation of sheets having a smooth and reproducible surface for reflectance measurements with a minimum of washing or contamination of the sample.
This TAPPI Standard Practice differs from other practices used in world trade in the manner in which sheets are pressed and dried. See Appendix.
TAPPI Standard Practice T 272 describes a procedure for using a sheet forming machine for making handsheets for the application. The purpose for having two methods is discussed in sections 4.3 and 4.4.
See Appendix for consideration of slow draining pulps and recycled pulps.