Document KGMd3K17jqpD4w4JY918qR04w
-5U. VAN LOO
Pont.
#148 - Examination of Khita Lead The series of single pigisent oil pastes reported in our Janu
ary report has been re-examined ofter 9 necks1 storage. These pastes were of equal Plastogrnph Consistency after milling. T/e now find that the plastic viscosity has dropped slightly on all pastes, the largest changes occurring with 18 dry basic carbonate white lead, Dutch Boy Dutch basic carbonate, 1405 dry anatase titanium dioxide, 2059 dry zinc oxide XX 503, 2295 dry zinc oxide ZZZ-35. The yield value has dropped on all pastes except Dutch Boy Dutch and Dutch Boy H.T.S. which had the lowest Values when fresh. The largest lowering is with 1403, 2059, and 2295. Thixotropy has increased slightly with 1707 dry zinc oxide XX 50, end decreased to e low value with 1403 dry and with 2173 dry rutile titanium dioxide.
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II. VAN LOO Cont.
177 - Pigment Studies
Work continues on the study of white pigment opacity factors.
Dnr. No .
Paint type I - House Point - Single opacity pigment plus ' extender formulated t 18,000 Holley units. P.V.C. 'con stant at SG by the addition of 20 F magnesium silicate.
% Opacity..So .Ft. Ab.-
Bright-ness 911 CR 93* CP. 951. CR S?f CR 9B< CR
**461 L Lithopone
86.3
1901 TiOg (Anet&se, LO) 86.5
52.5 . 44.8 252.0 215.0
37,2 176.0
30.2 138.0
26.3 118.0
**2132 Titanox RC HT 85.5 , 113.0 97.0 60.3 64.5
-
**2140 ' Titanox RC 1895 - : Lead Titahat
85.6 81.4
104.0 187.8
90.0 159.0
76.0 130.0
108.0
96.0
1897 TiBar HA
85.8
82.3 71.8 60.8 49.7 42.8
**Value$ have been checked twice before.
Send,-Lustre -Opacity.:
Several tests have been node to cooper* the various formula tions set forth in tho February 11 Semi-Lustre formula sheets. The recent modification which uses 200 pounds of rutilo Ti03 2173 dry instead of the 250 pounds called for by Alternate $ of the original instruction was also studied.
The-work was done in three groups of tests. First the vari ous alternates in the February 11 instruction were evaluated. Second, opacities were compared On paints containing (a) 575 pounds Titanox RC HT 2132 dry (alternate 3), (b) 250 pounds 2173 dry (alternate 5), and (c) 200 pounds 2173 dry (new formula). The third group of tests was made to justify the findings under groups 1 end 2.
Summarising tho findings by groups:
Group 1 - All points altornr.tes 1 - 8 aro substantially equal in opacity. Details given under table 1 attached.
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Group 2 - Paints containing: (a) 575 pounds 132 dry, (b) 250 pounds 2173 dry, and (e) 200 pounds 2173 dry. All give practically equal hiding.
Group 5 - In these tests the attempt was made to prove the results of tests under groups 1 and 2 above. Ey accomplishing the equal hiding reported above it was postulated that operations are on''Vsharp curve of diminishing returns when formulating SemiLustre rdth 173 dry. Tests of group 5 were devised to prove this experimentally.
It should be noted that the pigment volume was held con stant throughout these tests by a "makt-up" with extender pigment.
Results verified the above conclusion; that is, over the range 125 - 250 pounds loading of 2173 dry in Semi-Lustre it was proven that the opacity developed varies continuously with the pigment loading.
The graph below shews a plot of experimental data (determined by use of the Hunter refleetome ter. in conjunction with the regular pro cedure for determining opacity), which illustrates this point.
125.
150'
175
200
Pigment loading Pounds 2173 dra per 100 Gallons
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0007-SWP-000006802
1*177.- Cont. Using factors taken from the graph this relationship was found. At 97 contrast' ratio the factor for 2173 dry is 170 sq.ft./lb.
at a loading of 200 pounds, whereas at a 230 pound loading the factor is 141 sq.ft./lb. Using these factors in a manner similar to that used with the Holley system the following statistical comparison of paints made at these loadings would,,hold true.
A - 200 X 170 * 34,000 B - 250 scX41 s 35,230 It is understandable by this comparison that practical equiva lence of opacity in two paints is accomplished, one using 00 pounds 175 while the other eontotes 250 pounds. Summarizing the entire group of tests above it was concluded that the opacity variation at different loadings Justifies the seemingly wide disparity-between two paints developing equal hiding at a 20 dif ference in opaque pigment poundage. ` It should tot borne in mind that this date Is limited to Semi-* Lustre l<e pigmented with 173 dry. There is no assurance, (or confi dence) that when using 575 pounds of 2132 dry tho greatest efficiency' with teat-pigment' is being accomplished.
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