Form 9BL is a sealed chart designed for use with the TG19 Logicator. The top most area is striped, then black and then white, with overall dimensions of 7-5/8 x 11-3/8 in (194 x 289 mm). Form 23B has been discontinued
The individual stripes produced by the TG19 Logicator are identified by “INDEX” numbers (20 – 48) engraved on the instrument. These index numbers are also printed on the header overlay in matching locations so the stripes in the drawdown can be easily identified. The user places the header overlay over the 9B header when evaluating drawdowns made with the TG19.
Test Procedure: After the applied coating has dried, the operator locates the critical stripe, visually or photo metrically, and encircles the parameter of interest, as illustrated. It is generally accepted that the hiding power endpoint is not total visual extinction, but a degree of contrast just short of complete hiding, corresponding to a photometric contrast ratio of 0.98.
ASTM D 5007: In this standard, the hiding power of the wet film and then of the dry film are observed visually, and the percentage increase or decrease is reported.