INDUSTRIAL AND ENGINEERING CHEMISTRY
July, 1924
681
Varnish Studies' Relationships of Physical Tests and Chemical Composition to Durability By W. T. Pearce Noarn
D A B O V A A C R ~ C U L T U P ~COLLBcB, L ACRICUL~URALCOLLBCB, N.
D.
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Laboratory and e x p o ~ u t ctests were made on (I series of typicd that were made in %allon E L I A B LE laboratory methods for deoarnishes 0) known composition. EZ~OSUWS were made on maple quantities iI1 the college terrnining the nnipanels facing south and inclined at an angle 45 degrees. Each laboratory. Necessary inwas placed on exposureduring thefair, winter, and Jummel formation as to the comformityanddurabilityofthf and inspections were made w&y until ea& test hadfoiied. posit.ion of lnang of t,hese several types of varnishes tests, varnishes is given iii'hblc I. have been sought by many The iaborotory exminotion included elasticity , ,, ~ i ~ rate ~ ~of drying. i t ~ color, . and &d sf w&,. gases, and drefts. The Proposed Tentative varnish tecl1nob$sts. h e The tabulated data ore studied in order to aswrtain the value . f Metho& for Testing Oleotical methods2 have been devised for evaluatiiig the methods of iaborotory tests chemical in deResinous Varnishes (Dl.54color, viscosity, (fryingtime, terminin8 the durability of sewrol types of oamish. 23T), of the American Society for Testing Mateand elasticity, as wcll as the rials, were used for detereffects of water, gases, and drafts. Many chemical methods have been advanced, tested, mining tlie appearance, color, nonvolatile matter, and elasand modified. These include the deteriniliation of the n i ~ i i - ticiby or tougln~ess. In the case ,If varnishes havinga "ininus" volatile cont.ent, acid numhcr, metallic driers, and the peroent- kauri reduction value, a solution of neutral varnish oil in ages of fixed fatty oils and of fossil and recent varriisb resins. turpentine was used in place of the kauri solution. Ttris wiis The value of sevcral of these incthods is still to be deter- made by bodying varnish oil t o the coiisistency of pure mined, altlioogh many of them have been used for some tinie glycerol, then adding two parts turpentiiio to one of the oil. for determining the iiniformity and quality of the several For drying timc, wnter, gas, and driift tests, the inet,hodsgiven batelies of vasnislies made or purchased. For instance, the in Circulnrs 103 and 117 of the 13ureau of Siandards were specificatiot~s~ adopted by tho Federal Specifications Board, used. Viscosibies were determined with the Gardner-IIoldt for the use of the departinelits of the Government in the purwits taken to keep the varnishes in filled ples from freshly opened cttns ~ccreused chase of water-resisting spar varnisli and interior varnish, for any of t,he iaixirat.ory or Cxp6.0 >6.0 3.0 4.0 3.0 4.0 1.8 1.3 1.3 1.5 5.0 6.0 2.3
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Dry Hard Hours
HOT WATER Failed Passed Passed Passed Failed Failed Passed Failed Failed Passed Passed Passed Failed Passed Failed Failed Failed Passed Passed Failed Failed Failed Failed Failed Failed Failed Passed Failed Passed Passed Passed Passed Passed Failed Failed Passed Fnjled Failed Failed Passed Failed Passed Passed Failed Failed Passed Passed Passed Passed Passed Failed Failed Passed Passed Failed Passed
COLD WATRR Failed Failed Failed Passed Passed Passed Passed Passed Failed Passed Passed Passed Passed Passed Passed Passed Passed Passed Passed Passed Failed Passed Passed Passed Passed Passed Passed Passed Passed Passed Passed Passed Passed Passed Passed Passed Passed Failed Failed Passed Passed Passed Passed Passed Failed Passed Passed Passed Passed Passed Failed Failed Passed Passed Passed Passed
O F DURABILITY WITH KAURI REDUCTION VALUES AND WITH COMPOSITION
FIRSTAPKAURI PEARANCE REDUC-OF CRACKS, TION I N DAYS Per cent Sorina Fall Gallons COMPOSITlONa Rosin-tung -220 10 -110 10 Rosin-tung 90 15 15 10 Kauri-linseed 80 29 28 10 10 Kauri (3)-rosin (Wlinseed 15 -80 15 Kauri-pontianak - 50 29 I 5 10 Congo-linseed 10 - 30 15 22 - 20 28 36 Kauri (25)-rosin (2)-linseed 10 Congo-tung (3)-linseed (2) 10 - 30 28 36 Manila (20)-rosin (1)-tung (1)10 linseed (1) 40 51 36 Ester-tung'-(l)-linseed (1) - 60 28 15 10 15 Rosin-tung (5)-perilla ( 2 ) 90 10 15 Manila-linseed - 30 21 15 20 20 - 10 29 28 Rosin-tung and linseed 43 20 42 20 Kauri (15)-rosin (2)-linseed 20 10 57 Congo (6)-rosin (1)-linseed 36 20 Manila (20)-rosin (1)-tung (1)linseed (1) 50 51 36 20 28 36 0 Ester-tung (l)-linseed (1) 20 15 21 Rosin-tung (5)-perilla (2) 30 42 Kauri-rosin 35 30 64 65 35 30 51 30 51 42 30 Kauri 35 64 30 Manila-linseed 36 22 40 30 Ester-tung 58 100 50 30 Kauri (6)-rosin (1)-linseed 42 43 70 30 43 80 Congo-tung (3)-linseed (2) 21 Manila (5)-rosin (1)-tung (3)30 linseed (1) 80 93 71 64 42 30 Ester-tung (1)-linseed (1) 30 43 30 Rosin-tung (5)-perilla (2) 20 36 35 Ester-kauri 80 58 100 35 80 71 71 40 Ester-tung 70 64 71 40 42 Kauri-linseed 100 78 50 64 Ester-tung (4)-linseed (3) 70 65 50 64 Rosin-tung (5)-perilla (2) 60 58 Composition of Nos. 14, 7, and 36 not known ~~~~~
34 38 44 52 26 29 32
Color 1.5 1.5
TABLE11-ADDITIONALDATAON THE VARNISHES Set to Touch Viscosity Nonvolatile DRAFT Hours Per cent GAS Poises Passed Passed 59.25 3.10 Passed Passed 53.02 0.70 52.03 1.65 Passed Passed Passed Passed 45.16 0.65. Passed Passed 2.80 55.87 60.34 Passed Passed 3.40 Passed Failed 46.62 1.95 41.63 Failed Failed 2.50 Passed Passed 43.00 >10.00 Passed 40.57 Passed 2.25 Passed 43.89 Passed 2.15 Failed 48.30 Passed 1.25 Passed 50.63 Passed 3.40 Passed 44.68 Passed >10.00 Passed 47.57 Passed 3.70 Passed 49.60 Passed 2.25 Passed 42.26 Passed >10.00 47.16 >10.00 Passed Passed Passed 48.46 Passed 3.40 Passed Passed 2.50 58.65 2.25 Passed Passed 49.46 Passed Passed 2.65 49.85 Passed Passed 1.65 51.33 Passed Passed 4.00 49.40 Passed Passed 1.40 42.77 Passed Passed 2.00 49.66 Passed Passed 0.95 54,72 Passed Passed 47.57 2.00Passed Passed 48.13 1.35 Passed Passed 53,55 1.00 Passed Passed 48.02 4.35 52.66 2.25 Failed Failed Failed 53.62 1.40 Failed 5 4 , 08 0.65 Passed Passed 54.56 0.65 Passed Passed 56.66 Passed 0.85 Passed 54.70 0.90 Passed Passed Passed 47.22 Passed 2.00 45.18 Passed Passed 4.70 Failed 49,20 Passed 3.20 Passed 36.80 2.25 Passed Passed 44.66 1.25 Passed 37.34 2.20 Passed Passed Passed 36.63 1.40 Passed Passed 52.45 2.45 Passed 5.60 56.60 Passed Passed 61.60 Failed 3.70 Passed 50.24 Passed 0.95 Passed 41.98 Passed 0.95 Passed 2.25 Passed Passed 47.15 Passed Passed 2.75 70.03 77.57 Passed Passed 2.75 2.05 50.30 Passed Passed Failed 0.95 61.12 Failed Failed 2.15 55.55 Passed 1.40 52.25 Passed Passed
683
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TABLEIV-RELATIONSHIP OF LENGTHOF OIL TO KAURIREDUCTION VALUES Gallons of Oil t o 100 Kauri No. Pounds of Resin Reduction COMPLETE - 150 6 7 FAILURE, - 100 1 8 IN DAYS 11 10 130 Spring Fall 10 -110 14 7 8 10 18 50 51 10 57 25 20 42 10 43 31 40 65 15 100 8 15 92 71 49 0 15 65 57 20 120 17 65 100 - 90 23 20 58 20 100 29 10 26 20 20 65 85 20 50 32 30 3 100 85 0 30 22 36 43 0 30 40 36 35 35 30 20 100 40 65 30 53 100 106 50 30 27 141 85 70 35 54 134 134 80 2 36 80 238 36 113 35 80 134 45 40 100 92 65 37 70 64 50 206 42 60 202 50 183 56 203 80 50 92 108 206 202 120 203 183 208 DISCUSSION OF DATA 252 141 203 141
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203 238 100 183 206 134 141 266 203
141 99 71 252 203 203 252 206 106
ties of the room during the 1-hour cooling period before the panels were bent.
A study of Table I indicates that there is relatively little perishing of varnish films during a cold, dry winter. Varnishes that failed in a short period in the summer or fall exposure gave considerable durability in the winter test. The more durable varnishes gave much longer durability figures in the fall than in the summer. This is due in part to the fact that the varnishes, not failing before the winter came, went through the latter stages of disintegration during this slower perishing period.
INDUSTRIAL A N D ENGINEERING CHEMISTRY
684
The short oil rosin varnishes are less elastic and fail more rapidly than varnishes of the same length of oil, containing fossil or semifossil resins. The life of five 10-gallon rosin varnishes varies from 8 to 64 days, fall exposure, and gives a n average kauri reduction value of - 136, while three 10-gallon kauri resin varnishes lasted from 57 to 100 days in the fall test, and gave a n average kauri reduction value of -53. This, however, does not apply to blended varnishes, containing both fossil resins and rosin, nor to ester resin-tung oil varnishes. No further relationships of composition to durability can be found. Table IV shows wide variation in elasticity for varnishes containing similar percentages of oil. The diversity of materials used and the lack of uniformity in manufacturing these varnishes may be the explanation of this. The kauri reduction
Vol. 16, No. 7
values are in good agreement with the exposure data, as is shown in Table V. ACKNOWLEDGMEKT The writer wishes to thank the Educational Bureau of the Paint Manufacturers' Association of the United States (National Varnish Manufacturers cooperating) for assisting this work by donating funds for materials and for a n assistant. He wishes to express his appreciation to L. P. Nemzek, technical director of the Paint and Varnish Division, E. I. du Pont de Nemours & Company, and to L. V. Pulsifer, chief chemist, Valentine & Company, for their advice and interest in this investigation. A considerable part of the application of the varnishes and some of the physical testing was done by the writer's assistant, A. .N. Loudon.
Decomposition of Calcium Cyanamide on Storage' By K. D. Jacob, H. J. Krase, and J. M. Braham FIXED NITROGENRESEARCH LABORATORY, WASHINGTOK, D. C.
W h e n calcium cyanamide i s exposed to the atmosphere, it absorbs moisture and carbon dioxide. with the result that the nitrogen, which is originally present largely a s cyanamide nitrogen, i s partially changed to other forms. T h e extent of this decomposition i s dependent on conditions of storage a s to temperature, humidity, length of storage, and as to whether stored in bags or in bulk, and also a s to whether the calcium cyanamide has been hydrated and oiled. I n this paper are presented the resu!ts of a study on the nature and extent of the decomposition of calcium cyanamide under oarious storage conditions, o n quantities ranging f r o m a f e w kilograms to 450 metric tons. Some of the obseroations cover a period of 2.5 years. W h e n calcium cyanamide i s exposed in small lots ( af e w kilograms) to unusually seoere conditions of humidity and temperature for long periods, the cyanamide nitrogen is completely changed into other
forms, principally into dicyanodiamide and urea in the approximate proportions of 7 0 to 75 and 20 to 22 per cent, respectioely, of the total nitrogen. I n such a case, 7 to 8 per cent of the total nitrogen i s lost a s ammonia. Tests of this k i n d are to be regarded a s accelerated tests. for such seoere conditions are rarely, if ever, encountered in commercial storage. Untreated calcium cyanamide decomposes more rapidly than hydrated and oiled material. T h e decomposition of properly hydrated and oiled calcium cyanamide, stored in 45-kg. bigs over a period of 6 months, i s small under normal storage conditions a s to temperature and humidity. T h e decomposition of calcium cyanamide stored in bulk in such a manner that only a relatioely small surface is exposed to the atmosphere, a s in a silo, is almost negligible, the changes being confined largely to the top 20 cm.
HE important points with regard to the storage of calcium cyanamide are loss of nitrogen and nature and extent of the chemical changes occurring under various conditions. The conflicting and unsatisfactory data on the subject as given in the literature are due in part to the lack of adequate analytical methods and to the fact that, with a few exceptions, the experiments were made on only a few grams of material. The results of such experiments do not give accurate information on the storage of calcium cyanamide in commercial quantities. I n the course of the various investigations on calcium cyanamide a t this laboratory, numerous storage tests were carried out, under a variety of conditions, on quantities of material ranging from several hundred grams to 45.4 kg. (100 pounds) or more. In addition a study was made of the changes in calcium cyanamide stored in silos, a t U. S. Nitrate Plant No. 2 , Muscle Shoals, Ala., containing about 450 metric tons of material. The information obtained in these studies is presented in this paper.
failed to consider these points and erroneously concluded that *large quantities of nitrogen were lost from calcium cyanamide during storage. Corrected for changes in weight during storage, the results obtained by De Cillis,18*von Feilitzen,4 Kappen,14 Milo,21 Burgess and Edwardes-Ker,26and Meyer and Gorkow33 show that the loss of nitrogen is dependent on humidity and temperature and on the length of storage. Even in almost completely decomposed samples the loss rarely exceeded 6 t o 7 per cent of the original total nitrogen. Very little loss was observed from samples stored in dry atmospheres and practically none from samples stored in closed containers. Prankez6could detect no loss of nitrogen from a pile of 41.9 metric tons (94,000 pounds) of calcium cyanamide stored for 7 months in a warehouse located a t Jacksonville, Fla , the floor being only a few feet above the St. Johns River. As to the literature concerning the chemical changes which calcium cyanamide undergoes on storage, the different investigators almost unanimously agree that, owing to the absorption of moisture and carbon dioxide, the nitrogen originally present as calcium cyanamide is transformed principally into dicyanodiamide and to a lesser degree into urea. Some other compounds are also reported t o be formed a t the same time in very small amounts. Perotti,2 as early as 1906, observed that dicyanodiamide was the principal nitrogen decomposition product of stored calcium cyanamide. Henschelz3 later observed that considerable urea was formed under certain conditions. Hager and Kern28 found that when calcium cyanamide was treated with different quantities of water and stored in airtight containers the decreases in cyanamide and increases in dicyanodiamide were proportional to the amounts of water added. Miloz1states that in a 20-kg. bag of calcium cyanamide stored for 8 months in a
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PREVI ous INVESTIGATIONS The early work on the subject was concerned chiefly with the loss of nitrogen from calcium cyanamide during storage. Calcium cyanamide readily absorbs moisture and carbon dioxide from the atmosphere, increasing in weight and decreasing in percentage of total nitrogen. Some of the earlier investigators 5
Received January 31, 1924.
* Numbers in text refer to bibliography a t end of article.
