Document VJak0eDkJX84e2DB5E0z8mD3q

Indexed / BtTUBl' ID MiSHfil LABOBftTORV ?H%VSt MEMOMDUM HEPOHP # M*551 pr epar ed m mmm f , s x h g l eo t CCS 0 , H. Bullitt, Wilffi. Exp. Sta. J. Bo Bullitt, Wllo. D-7OI6 , D0 Me Burney, Wilm. D~t012 IBV W. Illff, Lab. lilt Do L* Herndon, lab, p. B* Evans, lab, Marshall Lab, Library (5) Patent Section Files 1810 Marshall Laboratory February 23, 1955 wt* i HID1HQ OF fflTAlXDMOXXDE AHD CELITB EXTHKDEH IH "FLQW~130TBw 3MPDTOTX0H: Super Seatone Shasta White contains less titanium oxide than wFloKoten White, but measurements made a year ago by the Pigments Department showed that it had at least as good hiding as ''Flow-Kote'' -per gallon. fhe comparison of hiding efficiency is complicated by the fact that "Flow-Kotefl is whiter than Super Kemtone, Hiding varies inversely with whiteness. For a comparison of hiding efficiency, "Flow-Eote" must be tinted to match the color of Super Kemtone, This memorandum reports new measurements to decide the question whether there is a real difference in the hiding efficiency of titanium oxide in the two paints. COHGLDSXOH: 1, Super Eemtone has significantly better hiding than wFlow*Kote" per pound of titanium oxide; the difference is about 10$, 2, fhis does not agree with the conclusion reached from the older set of measurements, because the hiding efficiency of Super Kemtone has been increased during the year since the older measurements were made, 3. Diatomaoeous earth (Oellte) Is responsible for the increase in hiding efficiency of Super Kemtone, 4. A modification of KFlow-KoteR with Oellte at the present gloss level has better hiding than Super Kemtone per N35466 2* pound of titanium oxide, presumably because the proportion of Celite to titanium oxide is higher . 5. The effect of celite is peculiar to emulsion paint. It does not increase the hiding of a solvent-type paint like Superwhite, ACTION? The use of Celite to lower cost and improve hiding is being Investigated under project P-10201, DETAILS? Comparison with Super Kemtone: Wo^lreWnt"TMSroBSctloh batches of low gloss ^low-Sote" White. P-391-U-46452 (591-012), have been compared with two recent samples of Super Kemtone Shasta White , "Plow-Koto" was tested both at its original whiteness and tinted to match Super Kemtone. Data are shown in Table I. All Samples were analyzed chemically for titanium oxide, Super-Xemtone contains more titanium oxide than is shown bn the label. The hiding efficiency has been calculated separately for the formula amount of titanium oxide and the amount found by analysis. The amount of titanium oxide in "Flow-Xote" found by chemical analysis checks closely with the calculated amount. ' can be seen in Super Kemtone under the microscope. A "Flov-Kote" modification, P-391-C-53110, was prepared to contain the maximum.amount of Celite"#266 (W-165) at the gloss level specified for "Flow-Kote". The pigment volume was kept unchanged at 38$ by adding China clay (W-l) as the remainder of the extender. The titanium oxide content was reduced to the nominal concentration in Super Kemtone. These changes reduce the raw material cost of "Flow-Kote" 13$ per gallon. The hiding of P-391-W-53H0 is shown in the last two lines of Table X. The increase in efficiency of hiding is evident, 1 In addion to "Silica and Silicates"/ Super Kemtone probably contains Lorlte extender. This material Is described as 8g $ calcium carbonate and 20$ dlatom&ceous silica. We have measured the hiding of paints in which it is the sole extender? in contrast to Celite, it contributes nothing to the hiding. fCcoirmfepearHisSonnew1 iwthheSthuepre" rCwhhiutetes increases the hiding of solvent type paints, the hiding of SupeOThite Gloss and Superwhite Flat was measured. Superwhite Flat contains Celite as extender. A DUP030003481 3. comparison with the hiding of "Flow-Rote*1 is Shorn in Table II. Since superwhifce has lower brightness than "Flow-Rote", the figures in the last column of Table II have been corrected to tillatli8?i?eSS f ^uper^bit means of the Kubelka-Munk Experimental Procedures fhe values in Table i were obtained on films bribed on black and white paper charts. For Table .IL films were drawn down on glass The reflectance of the film on glass was then read over a white backing and a black backing to determine the contrast ratio,, The variability of this method is found to be higher than for the brushed films. The figures for the hiding of %low-Kote" in Table I and Table XI do not agree. There is a difference between the brushed films and drawdowns too large to be ascribed to experimental error. The reason for the difference has not been determined. The spreading rate at 0.950 contrast ratio has been estimated from the observed values by means of the Kubelka-Munk chart W. The usual method is to make a graph of the experimental data and to interpolate at the selected contrast ratio. Some of the data ta Table I have been handled both wayjs, and the agreement between the graphical method and the=values estimated from the Kubelka-Munk chart is very close. SOBS: letters W, F. Singleton to D, MeBumey Letters J. B. Bullitt to J. V. Iliff Notebook 5578# FP. 8-27, 10/10/52 11/14/52 MARSHALL LABORATORf W . Fo SB5GLET0R (l) D0 B Judd, et als J Research Rational Bureau of Standards^T887-517, (1939). 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