1142
Patents granted to Stratfordl2 described the preparation and use of bentonite clays and the like in the refining of petroleum. Certain varieties have shown sixteen times the efficiency of fuller's earth for this purpose. The patents cover only the continuous process of preparing the clay by washing, treating with sulfuric acid, and drying; this removes the alkalies, alkaline earths, and some of the alumina, leaving a residue of very fine grains of aluminium silicate. Nelson7 states that boiling bentonite with 5 N sulfuric acid destroys its colloidal properties, about 85 per cent of its aluminium oxide going into solution as aluminium sulfate. This fact offers a possible solution to the origin of bauxite, as laboratory experiments show that such a solution of aluminium sulfate is precipitated by a solution of tannic acid after standing for a few days. Deposits of bentonite occurring in contact with pyritiferous rocks would really have part of their aluminium contents dissolved out by the sulfuric acid in the ground water, and such a solution of aluminium sulfate, it seems, would be precipitated by natural reducing agents, such as tannic acid or acid peat-forming bacteria, and thus form certain of our present bauxite deposits.
I n another paper Nelson13 gives further data supporting this view. Bentonite is a valuable emulsifier and in effect acts as a protector. The pioneer work of Pi~keringl~found that many insoluble substances would emulsify oils in water, and bentonite is one of this class. It would serve for emulsifying cutting oils, stuffing oils for leather, and many similar purposes. An important application of bentonite as an emulsifying agent has been made by Kirschbraun, who emulsifies with it asphalts, pitches, etc. These emulsions may be used as paints, for roofing, for the protection of structural steel, etc., and also added to paper pulp in the beater so as to produce a wide variety of waterproof papers. Because of its bodying properties, bentonite of the proper kind should be of use in thickening pastes, sizings, printing gums, shoe polishes, and many other things. Since all mixtures of this character vary greatly in ingredients and in their conditions of use, common sense, good judgment, and some experience are necessary if the best results are to be expected. 13
11
VoI. 16, No. 11
INDUSTRIAL A N D ENGINEERING CHE-WISTRY
U. S. Patents 1,408,655-6 (March 7, 1922).
14
Bull. Geol. SOC.A m . , 84,525 (1922). J . Chem. SOC.( L o n d o n ) ,91, 2001 (1907).
Paints Resistant to Sulfide Fumeslv2 I
By P. H.Walker and E. F. Hickson BUREAUOF STANDARDS, WASHINGTON, D.
N CONNECTION with the preparation of a suitable specification for paint to resist the action of sulfide fumes, it seemed desirable to prepare certain experimental paints and to note their resistance to darkening in both hydrogen sulfide and ammonium sulfide fumes. The paints were prepared by grinding, with a mortar and pestle, the weighed amount of pigment with sufficient raw linseed oil to form a smooth paste, allowing this paste to stand overnight and adding the remainder of the oil and the drier the following day. The same oil was used in all the paints prepared. Laboratory examination of this oil gave the following results:
I
...................... ............... ................
Iodine n u m b e r . . Acid n u m b e r . . ........................ Saponification n u m b e r . . Specific gravity. ...................... Heavy metals (Pb-Mn) Foots (per cent by volume),
............
'
191.9 1.25 189.8
0.9352
N o t detected 0. G
The cobalt drier used was a commercial sample of cobalt linoleate containing 1.75 per cent of cobalt and some rosin. The manganese drier used was a prepared oil drier made from raw linseed oil and manganese, abietate and contained 0.23 per cent of manganese. Several commercial paints were tested in comparison with those prepared in the laboratory. All the paints were brushed on small wood panels and given 72 hours between coats and 72 hours' drying after the last coat before subjection to the sulfide fume test. After being painted each panel was cut into three sections of equal length. One section was kept unexposed in a dust-free cabinet, one section was exposed to hydrogen sulfide for 24 hours, and the other section was exposed to. ammonium sulfide fumes for the same length'of time. The panels were placed under a bell jar connected to the proper gas generator, and a saturated condition was main1 Received April 14, 1924. Presented before t h e Section of Paint and Varnish Chemistry a t the 67th Meeting of the American Chemical Society, Washington, D. C., April 21 t o 26, 1924. 2 Published by permission of t h e Director, U. S. Bureau of Standards.
c.
tained for the duration of the test. The panels were then compared, their various changes recorded and photographed as soon as possible. I n some previous tests it had been clearly shown that lead in any form in the paint is subject to darkening, and a, few data on the results of those tests are given. --PIGMENT
(SO?,\-Chrome yellow
Titanium ZnO
%
%
A
60
40
B
60
10
C
A0
30
%
.. .,
10
cLIpUID
(40%)-
R a w linseed oil
%
90 90
90
Drier
Yo
EFFECT OR HzS Darkened somewhat 10Pb-Mn within 3 hours 10 C o Darkened slightly within 3 hours 10 Co Paint had pleasing light yellow color, turned t o dull, un. sightly hrown within 3 hours
I n the present investigation twenty.-five paints were subjected to the tests described. The reshlts are shown in Table I.
CONCLUSIONS 1-Ammonium sulfide is more detrimental to the color of paints than hydrogen sulfide, owing to the action of both the hydrogen sulfide and ammonia fumes. 2-For the interior painting of chemical laboratories and other places subjected to sulfide fumes, flat lithopone wall paints of the type specified in U. S. Government Specification No. 21 are recommended. If white is desired as the color, the paint should be free from lead. The use of a cobalt drier is recommended. For undercoats (priming on new work) the paint may be thinned with boiled linseed oil containing lead. White lead as the undercoat should not be used. For tinted lithopone paints, colors that resist sulfide fumes should be used; chrome yellow, chrome green, and other colors containing lead should be absent. If a cream or buff color is desired, yellow ocher or other iron oxide pigments should be used. Such pigments, while resisting
November, 1924
TABLE I-EFFECTS OF SULFIDE FUMES ON PAINTS (Two coats of paint were used except where otherwise noted.) DBSCRIPTION O F PAINT--------COLOR AFTBR H2S REMARKS ORIGINAL LIQUID Yellow White (40%) Linseed oil plus 0.2% M n No P b
I _ -
PIGMENT (60%) 6 0 % Ti(aj
40% ZnO (72.5%) 88.87' lithopone 1 0 . 3 % ZnO 2 . 9 9 " asbestine
csoii.
607' Ti 407' ZnO (69.4%) 8 2 . 0 % lithopone 9 . Syo ZnO
1143
INDUSTRIAL AND ENGINEERING CHEMISTRY
(27.5%)
42. 67' nonvolatile
Varnish vehicle containing Co No P b
(40%) Linseed oil containing 0.1% c o "
No Pb or Mn
07.4'3 volatile
(50.647,)
70% volatile 257' nonvolatile
S.Z'% silicates a n d color
S a m e as No. 2 except pigment contains trace of chrome yellow a n d yellon* ocher (50%) (50%). 100% s p a r varnish 60% Ti 4 0 % ZnO (40%) (60%). ' / Espar varnish, 1 / 2 raw 607' Ti linseed oil containing 40% ZnO 0.05T0 Co (40 % ) 160%) Linseed oil containing 60% T i 3 5 % ZnO a b o u t 0.0270 M n 5% vellow ocher Same a s No. 8 plus 1 p i n t spar varnish per gallon of paint (68%) (32%) Linseed oil containing 1 0 0 ~ basic o carbonate white lead 0 . 0 2 % LMn (38%) (62%) 1,inseed oil containing 50% ZnO 50% basic sillfate white 0.0270 M n
7
F l a t white
Slightly dulled a n d darkened
Slightly grayed
White
Cream
Yellow-brown
Light buff
Slightly dulled
Appreciably off color dulled and
Slightly dulled
Appreciably dulled and darkened Appreciably dulled and darkened
Varnish vehicle containing Co Small a m o u n t PbCrOa in pigment Buff White
Slightly yellowed
White
Slightly yellowed
Appreciably yellowed a n d dulled
Light buff
Yellowed
Yellowish brown, dulled
Light buff
Same as No. 8
About t h e same as
White
D i r t y yellowish brown
Gray-black
White
About t h e same a s No. 10
About the same as N o . 10
White White
N o t so marked a s N o . 11 Slightly yellowed
Slightly darker t h a n No. 11 Deeper yellow
White
Brown
Gray-black
White
Light buff
Dark gray
White
Yellowed
Deeply yellowed
F l a t white
Dulled, a n d d a r k streaks of t h e blackened lead showing through
Dulled a n d offcolor
F l a t white
Slightly dulled; equal t o No. 2
Compares favorably with No. 2
White
Dulled a n d lead darkening showing through
Badly yellowed
F l a t white
Slightly dulled a n d better t h a n No. 1 8 Slightly more dull t h a n No. 2
About equal t o No. 18
Yellow ocher
Unchanged
Dulled a n d darker
Gloss green
N o t determined
Badly affected t o dingy olive
Gloss red
N o t determined
Gloss yellow
N o t determined
'Badly affected, dull dingy maroon Badly affected, d a r k olive
Co a n d trace of Pb
No P b
---
AFTER ("42s Light brown
,I~
No P b
No. 8
lead . ___
Same a s No. 11, except t h a t 1 pint of spar varnish was added per gallon of uaint (40%) Linseed oil containing 0,057" C o
(6dk)
1 0 0 ~ basic o carbonate white lead
No Pb
(32%)
aOY0 linseed oil containing
0 . 0 2 % Mn 10% turpentine Same a s No. 2 plus 10% white lead on t h e pigment basis (60%)
(40%)
607' Ti Linseed oil containing 40% ZnO 0 . 0 5 % Mn First coat: basic carbonate white lead in linseed oil
Second coat: same as No. 2 F i r s t coat: same a s No, 2 plus 1 q u a r t boiled linseed oil (containing 0 . 1 2 % P b a n d 0.03% M n ) per gallon of flat paint Second coat: s a m e a s No. 2 F i r s t coat: basic carbonate white lead in linseed oil €or priming
No P b
Second coat: (60%) (40%). R a w linseed oil containing 60% Ti 40% ZnO 0 . 0 6 % Co Priming coat: same a s No. 18, first coat 2 coats same a s No. 2 Priming coat: same a s No. 18, priming coat T o p c o a t : No. 2 paint plus 1 pint boiled linserd oil (0,1270 P b ) per Fallon of paint (45%) 1 coat (55%) Linseed oil having 0 . 1 % 100% yellow ochrr
F l a t white
Slightly darker t h a n No. 2
co
(24.5%) Chrome green
(75.5%) 29,4y0volatile 70. 67' nonvolatile
Green enamel 1 coat
(18%) (82 %) Red enamel 10% toluidine red toner on 909" chrome yellow (33k (67%) Yellow enamel Chrome yellow (a) Ti = commercial pigment containing 25% TiOd, 75% BaS04. (c) Commercial paint. (e) Experimental paint.
hydrogen sulfide, are somewhat affected by ammonium sulfide. For gloss finishes a lithopone paint of the type specified in U. S. Government Specification No. 67 is recommended; the same provisions for the absence of lead in the paint, either in white or tints, hold true. Ammonia fumes, however, will be more detrimental to the color of these gloss finishes than to the flat finishes. & Forexterior painting around places subjected to sulfide fumes, the use of a titanium pigment-zinc oxide paint free
a
from lead is recommended. A fume-resisting paint of. this kind might be composed of 60 per cent titanium pigment and 40 per cent zinc oxide as the pigments, and about 85 per cent of linseed oil and 15 per cent of drier and volatile matter as the vehicle. Lead drier should not be used, but cobalt is recommended. Such a paint should contain between 60 and 65 per cent of pigment. For tinted exterior paints, up to 10 per cent of the pigment may be allowed for tinting colors; and these colors should be free from lead.
