An American National Standard Designation: D 724 - 99 (Reapproved 2003) INTERNATIONAL Standard Test Method for Surface Wettability of Paper (Angle-of-Contact Method) This standard is issued under the fixed designation D 724; the number immediately following the designation indicates the year of original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A superscript epsilon (e) indicates an editorial change since the last revision or reapproval. 1.Scope E 122 Practice for Choice of Sample Size to Estimate a 1.1 This test method measures the angle of contact when a Measure of Quality for a Lot or Process drop of liquid is applied to the surface of a specimen of paper. 2.2 TAPP/ Standard: TAPPI Test Method T 458 Surface wettability of paper 1.2Themeasurement of boththe initial angle of contactand the angle of contact after a defined elapsed period of time may (angle of contact method)3 be measured. 3. Signicance and Use 1.3A standard liquid (ink)for makingmeasurements is described. 3.1 This testmethod is useful in measuring the interaction 1.4 Other liquids including printing inks, writing inks, of paper with liquids in a variety of applications. adhesives, oils, and coating materials may be used upon 3.2 When using the standard ink described in this test agreement of those involved in the testing being done. method, the contact angle measured initially is often consid- 1.5 Two types of apparatus for measuring the contact angle ered a measure of the ruling quality of the paper. using the procedure in this test method are described. Addi- 3.3 When using the same standard ink, the change in contact tional instruments that can perform the procedure in this test angle between the times specifed in this test method, 5 and 60 method may also provide equivalent results. A different proce- s, is often considered a measure of writing quality of the paper dure using an automated instrument for measuring angle of when an aqueous ink is used. contact willbe found in Test Method D5725 3.4 In many applications, a contact angle between 90 and 1.6 The values stated in inch-pound units are to be regarded 100 degrees, when a paper is tested with the standard ink, as the standard. The values given in parentheses are for indicates that the paper will be suitable for general activities information only. where water-based inks are used. 1.7 This standard does not purport to address all of the 3.5 When this test method is used with specific non- safety concerns, if any, associated with its use. It is the standard inks of interest, or non-aqueous liquids, the users must responsibilityoftheuserofthisstandardtoestablishappro- agree in advance the data to be collected and how the data will priate safety and health practices and determine the applica- be used. bility of regulatory limitations prior to use. 3.6 Additional suggestions for more specific use of this test method will be found in Section 10. 2. Referenced Documents 4. Apparatus 2.1ASTM Standards:2 D 585 Practice for Sampling and Accepting a Single Lot of 4.1DropProjection/nstrumentAninstrumentcapableof Paper, Paperboard, Fiberboard, or Related Products projecting the image of a drop of liquid on the surface of paper D 685 Practice for Conditioning Paper and Paper Products onto a screen so that the angle of a line tangent with the drop for Testing at the paper surface can be measured. The general concept is D 5725 Test Method for Surface Wettability and Absor- shown in Fig. 1 and shall consist of the following: bency of Sheeted Materials Using an Automated Contact Nore 1While the projection instrument illustrated and described is Angle Tester antiquated, it describes the concept of the measuring procedure. Instru- ments are available in a more convenient form that serve the same purpose, that is projecting the image of the drop on a screen. 4.1.1 Angle Measuring DeviceA protractor or similar This test method is under th