INDUSTRIAL AND ENGINEERING CHEMISTRY
1066
was not immersed in the distillate, but the condensate was allowed to fall freely into the flask. No attempt was made to close the neck of the flask for fear of setting up a back pressure. If there were ammonia fumes or much dust in the laboratory air, the receiving flask would have to be protected by being enclosed in a container of washed air. An open beaker is not recommended as a receiving vessel. For the distillation the desired quantity of ordinary C. P. hydrochloric acid was diluted to a gravity of approximately 1.10 and introduced into the flask. The distillation was carried on a t a rate not exceeding 8 to 10 cc. per minute. Under these conditions only a negligible pressure was set up in the boiling flask. The distillation must be continuous from beginning to end. The first 75 per cent of the original dilute acid that distilled over was isolated for use as a high-grade reagent, the next 10 to 15 per cent retained as standard acid, and the remaining
Vol. 18, No. 10
residue in the boiling flask discarded. The amount of this residue was never less than 100 cc. The barometric reading was taken a t the beginning of the distillation, again after 75 per cent had passed over, and finally a t the end of the distillation. The last two readings were averaged for determining the strength of the acid. Conclusion
During the last four years constant-boiling hydrochloric acid has proved exceedingly satisfactory in this laboratory as a primary standard for the preparation of solutions to be used in acidimetry and alkalimetry. Careful work has always shown the error to be much less than 1 part per thousand. Normal sulfuric acid prepared from the foregoing samples was used in cooperative work with the Bureau of Mines and several other laboratories. The results were invariably satisfactory.
Rapid Evaluation of Baked Japan Finishes' By E. M. Honan and R. E. Waterman BELL TELEPRONB LABORATORLBS, NEWYORK,N. Y.
The service life of a japan film baked on metal can be in a suitable solvent a piece evaluated by determining the rate of decomposition finishes is very uncerof metal on which the japan of the film when it is placed in an 8.5 per cent phenoltain, especially in cerhas been baked and noting water solution. The effect of the time and temperature tain kinds of service. An the length of time necessary of baking the film and the cleanness of the metal preanalysis of the uses to which to produce definite action on vious to applying the japan can also be evaluated. articles so finished are subt h e j a p a n n e d surface. A The 8.5 per cent phenol solution is a desirable testing favorable feature of this type mitted in the telephone syssolution because its composition is quite constant at of test is the elimination of tem showed such service to ordinary room temperatures and is not changed by the the personal and mechanical involve two distinct types. evaporation of the water. variations. The most desirI n one type injury t o -the finish results primarily from a b l e s o l u t i o n having once chipping or scratching; in the other type destruction of been determined, the conditions of test can be so defined that the finish is due primarily to contact with hands, which the individual has no opportunity to interpret the results subject the japan not only to mild abrasion but also to the in an arbitrary manner. This sort of test may be used reliaction of perspiration. I n either type of service the finish ably to determine the degree of baking which a sample has may remain good for years or fail in a few months, but rapid undergone. The degree of baking in turn determines largely failure occurs much more frequently in thq second type of resistance either to mechanical injury or to attack by liquid service. Some of these variations depend not only on the contaminating agents such as perspiration. Although there severity of the service but in part on the quality of the finish are other methods of determining the degree of baking, these itself. Obviously it is highly desirable to have laboratory are usually qualitative and depend upon the color, resistance tests by which the life of japan finishes may be predicted. to scratching, or softness of the finish. I n the hand-contact type of service certain liquid immersion tests may be used as Several methods were devised to test the wearing qualities a direct measure of serviceability. This was attractive to of japan finishes. These included two general types of test the writers because in certain pieces of apparatus with which corresponding roughly to the two types of service-attack by mechanical means and by action of liquid reagents. they were concerned it had become apparent that the finish failed most rapidly where it came in contact with the hands. Combinations of these two types were also tried. The mechanical tests included rubbing, scratching, bending, Experimental and determination of physical constants of the films. Tests An attempt was therefore made to simulate such action of this type seemed to be of possible utility where abrasion and chipping are important factors in the service. Much work by immersing test pieces in liquids that might be expected to was done on these various tests, but all were found to possess resemble perspiration. A solution was made up approxiinherent defects. The conditions under which such tests mately as follows: water 98.59 parts, oleic acid 0.01 part, must be conducted are necessarily restricted. The interpre- sodium chloride 0.15 part, urea 0.14 part, acid sodium sulfate 0.03 part, monosodium phosphate 0.003 part, potassium tation of the results depends upon the strict maintenance of these conditions and on the judgment of the individual con- chloride 0.06 part; neutral fat 0.01 part. Samples were also ducting the test. Therefore, after many trials it was decided immersed in commercial oleic acid and in solutions of vato abandon this type of test for the present, even for cases rious individual inorganic salts of various strengths. I n in which mechanical injury is anticipated to be important. most cases a correlation was observed between the degree of The liquid type of test may consist simply in immersing baking and the time required to soften the film. For example, a two-coat sample baked 2 hours at 175' C. became soft in Presented before the Section of Paint and 1 Received M a y 24, 1926. oleic acid in 22 hours, and a two-coat sample baked 2 hours Varnish Chemistry a t the Midwest Regional Meeting of the American at 200" C. failed only at the end of 430 hours. I t was found, Chemical Society, Madison, Wis., May 27 to 29, 1926.
HE life of baked japan
T
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October, 1026
I S D U S T R I A L B S D ESGISEERI-VG CHEVIISTRY
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soon cause the formation of a few drops of the second phase. The specimens are immersed in the test solution and examined visually a t intervals of a few minutes at first, the intervals being increased in the later stages. The temperature is maintained a t approximately 22" C., since it mas found that a higher temperature increased the rate of destruction of the film. X sample is considered as having iailed as soon as the japan on half or more of the immersed area has become wrinkled or has sloughed off. The times of fallure given in the subsequent data are based on this standard. Often the film on some small areas, especially along sharp edges or along ridges or furrows, loosens more quickly than the film on the main area. Such localized failure should be ignored unless there are special reasons to the contrary. If this test is to be reliable solely as a criterion of the degree of baking, it is of prime importance that the metal shall be absolutely clean when the first coat of japan is applied. S o doubt various methods of cleaning may be used satisfactorily, but they must be carried out n-ith great care as to uniformity. The writers' experience leads them to feel that the factory method of cleaning metal which is to be japanned must be chosen with very great care. Visual examination of the surface is entirely futile as a means of control. For example, it was found that a mineral acid dipping of brass is poorly adapted to the production of adherent japan finish, whereas dipping in glacial acetic acid is effective, though both appeared equally clean. ,411 oxide should be removed without leaving any trace of residual salts. Mechanical means such as sand-blasting may be used advantageously. hccuracy and consistency of results with the test solution are possible only when the time between sand-blasting and spraying is kept a t a minimum. A lapse of a day, even when the -LOWER LAVER-UPPER LAYER-test pieces were kept in a desiccator, had a very noticeable Temperature Phenol HzO Phenol HzO effect on the results, and if the metal was allowed to stand c. Per cent Per cent Per cent Per cent 10 75.0 25.0 7.5 92.5 in the laboratory for a few days before japanning the re20 72.2 27.8 8.5 91.5 sistance of the film to the phenol solution was inordinately 30 69 9 30.1 8.7 91.3 40 66.8 33.2 9.7 90.3 short. I n all work discussed here the metal Tvas sand-blasted immediately prior to spraying on the japan. From this table it will be seen that at ordinary room temperConsistent results may be obtained on metals other than atures (20" to 30' C.) the composition of the upper layer brass, but the time of resistance to phenol solution fixed as a varies only 0.2 per cent in the phenol content, thus forming a standard for the behavior of a japan finish must be properly solution of a practically constant composition. As the two related to the metal on which the finish is applied. With phases exist in equilibrium they have the same vapor pressure. the same baking conditions the various common metals Evaporation of water from the upper layer causes some of the arrange themselves in the following order of decreasing rephenol to go to the lower layer. On the other hand, the addi- sistance to the phenol solution: copper, iron, brass, aluminum, tion of water dissolves some of the phenol of the lower layer. parkerized iron, and zinc. I n the case of alloys, such as brass, Thus, as long as the two phases exist the percentage composi- the percentage composition doubtless has some effect. Heat tion of each is constant a t a given temperature. It was treatment and cold-working of brasses also distinctly affect the therefore decided to confine the tests to the solution of phenol adherence of the japan during the phenol test. in water, having present also a small amount of the solution The thickness of the japan coating should also be standardcontaining the higher percentage of phenol to maintain ized, although this factor is of minor importance compared equilibrium. with the kind and cleanliness of the metal. Under given conditions, thick coats do not bake so thoroughly as thin Method of Test coat. Since the writers were interested primarily in the life of Typical Results japan finishes on brass, this metal was used in the form of The experimental results (Table I) shorn the correlation 20-gage sheet specimens 1 X 2 inches in area. However, it has since been found feasible to apply the test to a variety of between baking time and temperature with time of resistance telephone parts during the course of manufacture as a n in- to phenol solutions. Two coats of japan were sprayed on frePhly sand-blasted brass of the following composition: spection procedure. One part of phenol and 4 parts of distilled water are shaken copper 64.05 per cent, zinc 33.53 per cent, lead 2.40 per cent, together thoroughly a t room temperature and allowed to each coat being baked as indicated. The japan used was a high-grade commercial japan with stand. These proportions produce a stock solution which a drying-oil varnish gum base. Other products all of the contains the two layers mentioned above. A4 portion of the upper layer is siphoned off and allowed to ptand for a same type, however, gave equally consistent correlation of few minutes before the tests are made. Under ordinary degree of baking with time of resistance to phenol. The conditions evaporation of water from the test portion will length of resistance to the phenol solution under any given set of baking conditions naturally varies with different make> 2 Landolt-Pornste~n,Tabelleg, 5th ed , p 71Y of japans.
however, that the time required by these liquids to soften the film was too long to be useful in a routine test. The next step was to find a liquid or conditions of immersion which would act more rapidly. Boiling water affected the film very slowly, but blisters appeared if mater-3oluble impurities had been present on the surface of the metal before spraying. The use of other reagents a t elevated temperatures seemed undesirable on account of objectionable fumes, changes in concentration of solutions, etc. Various organic solvents, Imlar and nonpolar, were tried a t room temperature. Among these were alcohol. acetone, glycerol. benzene, aniline, and various aniline derivatives, chlorobenzene, nitrobenzene, ether, carbon disulfide, phenolic substances, and various hydrocarbon oils. Kone of these was entirely satisfactory, most of them being too slow in action; a few acted too rapidly to differentiate conditions of baking readily. Some were undesirable because of rapid evaporation; others had unpleasant odors. Some introduced fire hazards if used in the baking room, and others were too costly. The most hopeful material from all angles seemed to be the phenols. Since phenol itself is the most common of this type, it was decided to concentrate on this substance. The results gave promise, but were not entirely satisfactory until a water solution of phenol was tried. As is well known. a mixture of water and phenol separates on standing into two layers, the upper one of which is a solution of phenol in water and the lower one a solution of water in phenol. The upper layer contains about 8.3 per cent phenol and the lower layer contains about 70 per cent phenol. The compositions of these two layers a t various temperatures are as follows:?
0
while f:lilitr,: wcim i i i :L m m t l i o r two iii some s a i o p l i : ~I~ukc~il mcurdiiig to metbods Ireretofore regarded as cinmnei aeccptnille. Other Possible Uses of the Phenol Test
'l'liis test was ~ l r ~ s i g n cprimarily il to detect a comlitioii of l,aked jnpmi firiisli leading to short life when the part is Iiandln~. This eonilitim w:zs f m n d to be asioc imiier-baking, w l i i d r the plimiJ test detects sat Tiierc RISO seem io he o t l m iises to which this tes put. of results ditiiiiied urtder carefully coirmakw it, pwsiiilc to set, a Raking staialarri liquid japan ptswli 11 slioiild be rrqiiireil bo mect. In the same ma~nieriin unknown japan iiiay he tcsteii to sce iS it will mniimii to est,tiWislired linking eonditiims. has Ireen stated above, the surface prior to jiipiimiing he alxwlutely clean iii order to get consistent results in the phenol test. Conversely, the test can be used to dedcct improperly prepared sui-faces, other factors being colitrolled. Defectire sisrfase, whieh seems to he more often rclated to an oxide film than to dirt 01' grease, sometimes has :L deleterious cficet on the wearing qualities of tlie film, although the writers' evidcnce is not, complete enough to mnkc a gcncral statement. Bnothcr peculiar action and possible use of the test was found when some brass xvhich had hoen licavily worked without siibscquent annealing w t s found to act queerly nn being japanned. The resist,ance to phcnol solution was low, yet tliero w i s an unusual amount of dullness which is usiially iLssociat,ed with over-baking in the finished product. After sucli pieces ivese annealed t l q acted nosmnlly.
i
i
S
Correlation with Kspid Service Test
In i,rdes to get iiat;i m i tlie relation lietwen the baking d japans and thair behavior in a service whore contact with thc hands predominates as a destructivc aFencp, japms lwre applied oii knohs of clocirs i i s d for renndmg aticnrlancc of employees of tlie iahurntm knobsarc handled by a definite niimlrcr l l l ~ ~ ~ , - ~ ~ ~ , , ~ j , ~ , @ @ of i n d i s i d u a l s f o u r times a day and the amoimt of haiidliiig d i c i t is ncces.q:rr? to protliice 8, failure in the finish m i lie measured accurately. The composition of tlic knohs used was as fol101s~: ropper 61.70 pes cmt, zinc 35.87 per cmt; lead 2.39 per ccnb. i i w c.--6nmiii. Thi, frc~hlvsam-blasi,erl knohs were gimn two coats of japan. Each of the suemssivr coats on an indivirliiiil knoh , i l , i c ,-~,,Ojmin, ikerifir t,hcsnmclengtli of timeand at. thc: same tcmvrraturc. Onc-fourt,li It, is often desirable to japan a SIBW type of surface which is of tile knobs wero baixd a t 170" C. for 60 mimitcs, onerollrth at, 170" C. for 105 niiniibes, one-foiirt,li a t 195" C!. for nirt kno.u,n to bc adapted for the application of japan. The (io miimtes, and tiir rcmainder at 1%' C. f k r 105 mimltes. ~ilieiiolteat could probably he used in this connection. For nple, zinc is notoriously a poor snat,erinl to japan a.nd a Two knobs from each set were t&ed in tlic phenol solution. 'l'nblc I1 shows the time of rcsistanee t.o the test solutioo. ji\pim film baked mi zinc has very little rcsistanee to the phcool solution. nrass given a black nickel finish and subseTahlf I t --H&EfanCe to Phenol Solntion of J n p r ~Plnirh 01) Bras8 qirently jap;anned was found io m a r very poorly. When sncli Knohs prirdiict is subjected to t,he phenol test the film sloughs off in an amazingly short time compared with copper, iron, or brass. The phenol tcst secms t,o gire a rather accurate indication < I f the degree of cementation between the japan film and the irideslying metal, and thus becomes a tool for studying i.he lxiliing of japan whicli it is Isoped will he of value to otlier workers.
r) (D
0
0
000
T l ~ crcmaiiirler of t,lie k i d s \yerc placed on time clorkn iii regular seriico. At the end of 7 months the knohs were rem o d from the clo 'I'he results s h o ~ e dthat uiiderinking was the chief cause of unsatisfactory wear in tiiis casc. ?qie accompamyiitg photograph was taken after the tests wen rompletrd. With careful control of baking conditions this japan will \idhsiand over 15months of service oii these clocks,
Synthetic Methanol Patent -On June 9. 1026, a patent W ~ L S eraiitcd Charles Henry, former director of tiic Lalroraiory of the Physiology OF Sensation at the Sorhoiinc, lor the produdion of syotl~eiicmeihylalcohol. Ileclaiinsthaihccaiidctermincmalheinaticaiiv rather than cmniricaliv the best catalyst resuired for a given &tioil. f u r t h c r i;xforrn&n is obtained irom the Chcmi c n l 1)ivision. Depnrtmcnt of Commerce, Washington, D. C.
