Document 4aOgJDb6JnJk1eJZY8BRvo6y1

0007-SW F-043277 0007-SWP-000126625 0007-SWP 0007-SWP-000126627 0007-SWP-000126628 0007-SWP-000126629 0007-SWP-000126630 0007-SWP-000126631 0007-SWP-000126632 0007-SWP-000126633 0007-SWP-000126634 Effect Of White Pigments On Physical Properties Of Paint Films Hy K. J. Da*r%t /f.t and t. If. Baier MrmmAtym PIGMENTATION is one of the para mount factors m the formulation vidua! pigments, it was necessary to make a broad study of single pigment of house paints to obtain durability.pain! films. Physical property meas The largest proportion of exterior urements included in this study were bouse paint Is baaed on the use of tensile strength, percent elongation, white pigments and linseed oil. Pig elasticity. Sward rocker hardness, ments used in white base house paints moisture permeability, moisture sorp may be classified Into two groups, tion, abrasion resistance, shear hard namely. (1) reactive pigments or; (2> ness, adhesion to metal, reflection, non-reaetive pigments The commonly gloss and disteasibihty over a conical used reactive white pigments are basic mandrel. Microscopic examination* lead carbonate, basic lead sulphate, were made of the films and pigments I zinc oxide and leaded zinc oxides. In and some chemical determinations i the second or non-reactive group, the were made to show the quantities of mast commonly used pigments are reaction compounds or soaps formed titanium dioxide and zinc sulfide The both In the pamt container and within so-called extender pigments, of which the paint film as it aged 1 fibrous magnesium silicate is probably The pigments used in this inveetiga ! the most widely used, are also em- tlon were Carter process basic lead ployed in house paints carbonate,i Thompson Stewart process I It is known that most single pig- basic lead carbonate,i lead salicylate, 1 nient paints are not particularly dura basic lead sulfate, sine oxide, titanium ble. However, if the physical prop- dioxide (rutile type! and fibrous mag ' erties of the individual pigments are nesium silicate. These are the pig- properly established and advantage is ments commonly used in house paints taken of these properties, balanced j formulations may be designed to pro Particle Size duce durable paint films with a combi nation of pigments even though indi vidually they may produce poor paint Alms To determine what physical proper ties are imparted by the various mdi- The comparative particle size and microscopical appearance of the six pigments included in this study are illustrated in Figure I. rt is apparent from Figure I that lead salicylate has the coarsest particle I size of all the lead pigments. Basic lead sulfate and basic lead earbonate- Addins (Hrtff beloro Mi Toronto ond Ywrmth Production Club, April if, 1949, and the Sow York Point mod Ymmitli Produc tion Ctub, Septm&r 2, 1949 Tbrt paper will ap peal in tom* tutuie itsue of tf>* "Offioel Pigtti Iditor Carter process are of similar particle size while the TSP white lead is defi nitely finer All these lead particles have a third or depth dimension much less than the length and breadth of the particle In other words, the particles (Turn to Page 46) American Paint Journal * 0007-SWP~043288 0007-SWP-000126635 lures of the other pigments were si 1.000 diameters. This forcefully illus ness Some threetmgs, typical of zinc trate* the extreme coarseness of this oxide, are evident. As in the case of material, compared with the pigments white lead, zinc oxides are marketed used in house paints i m various ranges of fineness. In fact, Titanium dioxide is one of the finest ) a special "rubber grade" of zinc oxide particle size white pigments on the is so fine that it begins to lose its market 2 Even at the high magnifica optical properties and is considered tion apparent in Figure I. the particles unsatisfactory as a house paint pig are only minute dots, which shows ment. they are only a small fraction of a : With respect to the effect of particle micron in diameter. Since this prod ! size on the physical properties of single uct is ao fine it is natural to wonder ! pigment paint dims, white leads of what these particles would look tike t finer particle size seem to impart in an electron micrograph Their ap i somewhat better physical properties pearance is exhibited in Figure III \ In the case of zinc oxide, however, It is evident from Figure HI that 3 there is some indication that the the fine particles take on some shape l" coarser particle size imparts the better The fine dots show a characteristic j physical properties angular outline. Electron micrographs 1 Fibrous magnesium silicate is con- of the other pigments indicate the > stituted of relatively coarse particles. same general shape as the light micro however, it imparts certain desirable scope shows. The hexagonal shaped properties that appear responsible for particles or the acicular shaped par f its broad use in house paints Figure ticles in the other pigments ere some I IX is a photomicrograph of magnesium times more apparent in an electron \ silicate at a magnification of only 250 micrograph but basically the same f diameters, whereas the previous pic- particle shape is exhibited To prepare the single pigment paints for this physical property study, the above six pigments and one extends were ground individually in paste fmm using refined linseed oil as the grinding medium The pastes were ground on a three roller null passing the pasu through twjce to insure a good guild The roller mill was adjusted to givt t fine grind The resultant pastes were all reduced to a pigment content of 24 per cent by volume by the addition of more refined linseed oil No free thinner was added, but 3 per cent ur liquid drier was used Table I give-, the composition of these paints Lead sabcylateJ is a new lead product used for stabilizing paint films and plastia^ It is the normal lead MofiitlJum SJffcet* salt of acid It materially fi% 2 --Ph+immltfofrmph 250X increases*.gloss retention and retards iTurn to Paze ?S> HO American Patnt Journal } I 0007--SWP-043289 I 0007-SWP-000126636 !/ Effect Of White Plgmentx On Paint Films (Continued from Pace 46) the chalking of oil bate paint, especi ally when used in combination with non-reactive pigments. Due to these Pain; % % Lb. / No Material Plcmenl Vehicle Oa] 04D Lead SatleyMtt 43 74 41 31 10 54 eon Titanium Dioxide mutitci 81 H 41-41 13 II SC-43 Bute Lead Carbonate II M 31 13 II 81 4443 Buie Uid Carbonate .. . U 34.74 14 31 4044 4C45 4044 Bal Lead Bullet* 81 37 33 13 )U Zinc Oxide ttM 34 M 1114 Pibroui Mafn*xium filllCSt* 41 47 8183 11 80 `Carter Prpttu "HimiPh o Stiwart frveau characteristic*, it prolongs the color /aatneas of colored or tinted paints where the reactive pigments content is small Lead salicylate also Improves the performance of red lead primers in corrosion inhibitWe paints, particu larly on salt water exposure Lead salicylate was included in this study because of its beneficial properties m stabilizing paint films . * 4t Ttfmivm bloxide, Swill* Fl$ J ---licet ronmicrograph f 0,000JC Another new type lead pigment used m house paints of today is referred to as a basic silicate white lead and b called 45X. Pigment 4SX was not in cluded tn this comparative physical test program when it was started about three years ago, nevertheless, its importance warrants discussion Particles of the pigment 45X have been produced on the basis of a new pigment concept t In a paint film, the core or central portion of the particles practically never comes in contact with the vehicle Microscopical examination of the particles retained in paint films after five years of ex posure shows that the pigment par ticles retain their original si2e and shape In view of this a pigment has been developed having a neutral or non-reactive core but with a coat ing or surface for the particle that u reactive. This is the type of particle that has been produced in 45X A core of silica is surrounded by a thin coat ing of lead silicate and some lead sulfate. Lead sulfate acts as a light stabilizer for the lead silicate Such a particle conserves metallic lead dur ing the present shortage Our ex posure data with this pigment im proves as it accumulates After the above paints were aged for a few days the necessary panels weie prepared Six panels approxi mately 30 inches long by five inches wide were prepared from each paint Two panels were on tinned iron, three on cold roiled steel and one on patapar paper In order to have films of fairly uniform thickness, ail paints were ap plied with an inclined automatic doc tor blade * After the panels dried, they were primed on the back and edges and were exposed at the National Lead Company exposure test station at Say- ville. Long Island Panels were ex posed cm the fences m a vertical posi tion facing south Periodically, por tions of these panels were returned to 76 American Pamf Journal 0007-SWP-043290 0007-SWP-000126637 H. Soap Extraction Apparatus I. Sward Rocker Hardness Tester. The Hunter Reflectometer* was used for the measurement of 60" gloss and demonstrate the durability of ample reflectance. The petrographic micro I pigment paint Aims on wood Figure scope was used for the particle size I IV shows the comparison of these pan and particle shape studies The stere els as they appear on the fences at the oscopic microscope was used to ex age of one month, six month9 and amine the paint films for the degree twelve months of deterioration. The Gardner-Parks , Figure IV shows in general that the instrument1 was used to determine the reactive pigments are more durable tensile strength and the percentage ' as single pigment dims However, elongation The Sward rocker hard when the properties of the non-reactive ness meters was used to measure the t pigments are balanced and combined surface hardness. The Taber abraser* , with the properties of reactive pig' was used to measure abrasion resist ments. very durable paint Alms may ance and shear hardness. The conical be obtained mandrel * was used to note the point ' Apparatus at which the film could be distended '* Same of the apparatus used in mak- before cracking or breaking away from mg the physical property roeasure- the base to which it was applied. The i ments for this investigation is illus water permeability was determined by trated in Figure 5 the New York Production Club ' * A Hunter Reflectometer method.** The cups are illustrated at I I B Petrographic and Stereoscopic Microscopes '*E*' m Figure V. Film thickness meas urements were made on all panels C Taber Abraser using either the Ames Dial Micrometer or the Magne Gauge Extractions of D. Ames Gauge and Magne Gauge the paint Aim for chemical determina * E Water Permeability tion of soap formation J? were con 4 F Conical Mandrel ducted m the refluxing apparatus I G Gardner-Parks Tensile Strength shown at "H" in Figure V. Extrac j and Per Cent Elongation tions were made with a vehicle con- Loft Holt Mogntfum Silteol, titanium Dlotudt, serf Zinc Sulftdt Halt Bout iooj Cofhonots, Zmc Ok J4, ond Satie On* Month Two Months Tw*l* Months I 0007-SWP-043291 0007-SWP-000126638 reactive pigments, all have a very similar whiteness st the relatively high level of approximately 70 per cent. Lead salicylate, also a reactive lead Such extensive date are gathered compound, has a relatively low hiding ! from a program of this type that pre `power and consequently shows a low sentation in a concise and meaningful order of reflection The titanium di manner offers some difficulty. The oxide panel, which Is whiter than all important object is to establish the the others initially, and normally stays 1 trend of the various values throughout that way, became mildewed in this the life of the paint film. How does senes, and as a consequence the white the hardness or the tensile strength ness was materially reduced. Mag change from month to month? It is nesium silicate naturally shows a low not necessary to know the exact data reflection, but when it chalks heavily | obtained because it is the general rate the whiteness increases i of change of physical properties, with Figure VII shows the change of gloss \ time, which governs the life of the with time. The gloss was measured * film. at an angle of 60* Lead salicylate has j To portray the manner m which the most unusual gloss retention proper I* various physical properties change with ties This compound as a single pig 'J time, graphs have been prepared and ment stabilizes a linseed oil film better * Figure VZ illustrates the change m than any other compound that was I reflection characteristics of the paint tested Zinc oxide, in this series, 1, film with time. It is evident that 2inc showed better gloss retention than oxide and the two white leads, the usual The three lead pigments lost I I I I j i I ) t fl*. S. SO American Paint Journal 0007-5WP-043292 0007-SWP-000126639 // their gloss m approximately two months of summer exposure and after three months, all show practically no gloss of increase in surface hardness i quite high, but they would all be classed as comparatively soft surfaced films. Figure VIII shows the results of the Shear hardness was obtained with Sward rocker hardness tests. Sward the Taber shear point. It is the force rocker hardness is primarily an mdi* required to shear the paint film with cation of the condition of the surface out cutting through to the metal It of the paint him. Lead salicylate, is affected more by the through hard zinc oxide and Thompson-Stewart Proc- ness of the film than is the Sward ess white lead alt produce relatively rocker hardness test There are some herd surfaced dims. The rate of in changes but basically the same pig crease in surface hardness is pro ments show the hardest films Zmc nounced, as may be noted in the graph oxide indicates greater through hard Carter Process White Lead has a some ness than the other films. It should what similar rate of increase in sur be noted that the rate of increase in face hardness but it does not attain through hardness is very steep, reach the degree of hardness of the Thomp- ing its general maximum in about two 1 aon-Stewart Process White Lead. Basic months Magnesium silicate, basic lead s lead sulfate, magnesium silicate and sulfate and titanium dioxide produce i titanium dioxide all produce relatively Alms that are too soft to be practical soft surfaced Alms Their initial rate and show no increase in through hard- *i) F)f. 84 American Paint Journal 0007-SWP-043293 0007-SWP-000126640 periods of exposure. The separated paint Alms are difficult to manipulate. Figure XI shows that the rate of de film* increased to a maximum in about crease in elongation is quite pro three months which may be noted in nounced. There are some pertinent ) Figure X, The strength of these films notations on this graph First, the ^ is appreciable, approaching the range lead salicylate Aim stretches over 100 of 40*50 kilograms per square centi- per cent of its length That is most meter. After three months, the tensile unusual in any p&mt Aim Secondly, strength began to decrease However. seme oxide has a very Jew percentage ,, if a means were available to accurately measure the tensile strength of very of elongation even as an initial Aim f small pieces of paint Aim, we feel the tensile strength would be increasing for It appears to be too low for a durable paint Aim Most of the lead pigmented 1 a much longer period of time It is Alma exhibit relatively high percentage ! apparent from Figure X that the re elongation, compared with the other s' < active pigments impart considerably pigments * greater tensile strength to the Aim. Paint Alms also exhibit elastic u: } Similarly it is difficult to determine resilient characteristics After the the percentage elongation of the paint Alms have been elongated or stretched, g Alms as separate entitles (that is, as illustrated in Figure X, they tend to . stripped from the base metal) for long return to their original size or length H 7 --40' dost 86 Amcrn an Paint lourn/it 0007--SWP-043294 0007-SWP-000126641 zt r T ee Fig. This elastic characteristic is best lllua- Magnesium Siltcat* trated by the data in Table 2 Original . I MoiVh IS 1 < 21 14 Table 2 Film Lead Salicylate Omni#! 1 Month i Months 4 Months Titanium Dioxide Original Permanently ^ elongation Extended 110 11 )E? 3$ un 43 7 37 1 4 *; Permanently Film % Elongation Extended Basic Lead Carbonate Origins 1 SO 2 2 1 Month 45 * 5 2 Months 3 Month* U 50 0 'Sasic Lead Carbonate Original 1 Month 30 1 4 35 IS j Months 14 4 0 13 0 Basic Lead 3ulfie Original 20 1 i Zinc Oxide Origin*) 7 J Month 30 * Carter Process 'Thuirp*r*n-Stearl Process Although Table 2 illustrates the sur prising' elasticity of paint films, it is evident from the observations that the paint films also have some plastic char acteristics Films that are capable of extending from 40 to 100 per cent of their length seldom are able to return of their own accord to their original size However, if the percentage elongation is low, the film usually re turns to its original sise Distenatbihty is a term associated with elongation. The term diatensibility has been used to signify the stretch of the paint film when il is supported by the base upon which it is September 20, 1948 sr 0007-SWP-043295 0007-SWP-000126642 applied Where the Alms are attached to the base they retain their elonga tion for a much longer period of time, which means the adhesion of the paint Aim plays a vital part in the measure ment of this physical property. If the pamt Aim disintegrates badly, it is difficult to measure the distensibility. Figure XII makes it evident that prac tically all the pamt Alms retain enough distersibility (above 10 per cent) to cope with the average expansion and contraction of wood. Wood expands, on the average, up to 4 per cent with the grain and about 10 per cent across the gram Zmc oxide has a low order of diatensibihty In fact the distensibihty may be too tow to resist the full expansion and contraction of the wood Water permeability and the amou of water picked up and held within the paint Aim appear to affect the durabil ity. Figure XIII shows the water permeability of the film over a period ot a year. It la evident that sine oxide, basic lead carbonate-Carter Process, lead salicylate and basic lead carbonate-TSP have a rather uniformUy low rate of transfer of water through the paint film. Basic lead sulfate, titanium dioxide and magnesium silicate trans fer appreciably more water initially, and the quantity increases as the film ages. Those films transferring the large quantities of water were the less durable ones when exposed on the fences at SayvUle. The water sorption or the amount of SHEAR HARDNESS FACTOR Fiq 9 --Tabtf Shear Hmrdnttt 90 American Paint Jcv.rnel 0007--SWP-043296 0007-SWP' water that these pamt Aims pick up and hold within the Aim is noted in Table 3 Table 3 Film BiUe Le*d sulixte Zinc Oxide . MtgrttftJum Sllieate lead Salicylate Titanium Dioxide 'Bute Lead Carbonate 1 "Buie Lead Carbonate 'Carter Proceti "'Thompson Stewart Proceu From Table 3 it is evident that lead pigments in genera) have a high re sistance to pick up of water within the paint film The other pigments and magnesium silicate pick up appreciable water, the content going as high as 23.7 per cent. This affinity for water, of pigments other than Jead, is ap* Alms usually cause the rain to appear as droplets on the surface while the other pigmented films are better wet by the water and, therefore, the water usually exists as a film on the surface Further evidence to substantiate the above is the fact that lead pigmented films may show water spots after a KILOGRAMS PEA SQUARE CENTIMETER Fij id Sifnglh 92 American Point Journal 0007--SWP-043297 0007-SWP-000126644 storm white films containing other pig ments do not. In general, those films showing the lowest water sorption were the more durable Alms. It is apparent from Table 3 that the waLer solubilities of all these paint films are similar except for lead salicy late. which has a much higher water solubility. This is due to the com* pound itself exhibiting a alight water solubility. The films other than lead salicylate show an average of approxi mately five per cent water solubility, which appears to be due primarily to the vehicle portion of the paint film. The abrasion resistance, as deter mined with the Taber abrmser, was obtained for these various paint films as exposed over a period of months at Sayvtlle. Actually, these paint films as a group would be classed as the s type, especially in early stages of their life, so that the abrasive action of the machine may Imbed material into the paint film instead of completely wear ing it away. However, as may be noted In Figure XIV, some difference In abrasion resistance of these films is observable as the age increases. The harder paint films such as those ob tained with the sine oxide and the lead salicylate show the better abrasion resistance. However, the abrasion re sistance of soft type linseed oil base films does not appear to be of great value In & correlation of physical prop erties. The adhesion of these paint films to metal, as indicated by the New York Production Club Method, is indicated N0UPDN013 ftg. 11 --Efongolton 94 American Paint Journal 0007-SWP-043298 n Figure XV It Is interesting to as split off some fatty acid from the note that the adhesion increased, as triglycerides, probably through hy these paint films aged, until the paint drolysis. These products tend to liquify, films started to show some deteriora plasticise or Molten the film. Some tion, This increase in adhesion seemed psmt systems actually become so to be common to all the paint films but gummy that they cannot be handled was most pronounced Cor lead salicy during this softening period late. The high degree of adhesion for Reactive pigments within the film lead salicylate was also roost evident slowly unite or combine vfith the de in the panels as they aged at Sayville composition products of the vehicle and The adhesion of white paint films to prevent extreme softening of the film. wood is a very important property. The controlled formation ot soaps Chemical Determinations within the film as the film ages actu Alter a paint film has dried and set, ally enhances the life of the paint film t \ there are still many chemical reac Some soap is formed in the liquid psmt \ tions taking place The oil film con held in the container, but the soaps \ tinues to oxidise and set free some that form in the pauit film produce short chain acidic compounds, as well the most beneficial effects Some indi- & b i Septcmbcr 20. 194# 95 007-sm>-0432' o 0?. VOLUMES Of FAINT LOT IN C C tiW. I)--Wwt*r P*m*+W*r MONTHS CVPOSffi t,g 14 0OO7-SWP-O433OO 0007-SWP-000126647 4 small quantity at two months and Pigment Uaed 8aake Lead Carbonate * Baric Lead Carbonate 8aale Lead Sullata Lead Salicylate Zlne Oxide Titanium Dioxide Macneslum Silicate Na K Al Me 'Carter Process '`Thompson Stewart Proceaa Table 4 111 Paint Container on 0 09 0C| 93 03 Linoieate In Paint Film 3 Mentha i Mentha 19 Mentha 3 9 13 0 19 4 91 13 1 19 0 00 0 0 is a 31 i 30 4 13 3 149 191 J.O 00 3 1 30 10 ao It is evident from Table 4 that only a small fraction of a per cent of soap is formed m the paint container The hign value for lead salicylate is due to limited solubility of that compound in the extraction vehicle As the paint increasing to a relatively large quan tity at twelve months No reliance is placed on the exactness of the quanti ties of soap reported in Table 4, but considerable importance is attached to the increasing amount of soap found i i 1 100 American Paml Journal 0007-SWP-043301 0007-SWP-000126648 as the Him apes. of the paint film. Normally, the acidic decomposition products form in the paint him at a faster rate than the soap formation reaction proceeds This is highly ben eficial, as advantage is taken of both the plasticizing action of the acidic compounds and the stabilizing reaction of the soap formation. The beneficial effects of these reactions are probably best illustrated by Figure I which evinces the longer life of SayviUe ex posed paint films made with the reac tive pigments The properties of many modern house paints are obtained by balancing the deficiencies of one pigment by the advantageous attributes of another, for example by counteracting excessively high reactivity of one pigment with the non-reactivity of another pigment. A mixture of pigments may impart better water resistance or lower water permeability than would be expected by considering the arithmetic average of the Individual components. Mixing pigments makes possible some control Conclusions From the foregoing, it is apparent that the supposedly simple phenome non of the drying and weathering of a paint dim is really exceptionally complex both from the physicist's and the chemist s point of mew These data point to the need of a better application of the knowledge of physi cal property data in the pamt industry for the development of improved house pamt pigments and to a better com promise of physical properties within the paint film. From the data col lected in this work, such improved pigments should impart low water per meability, low water sorption, high visible reflection or high hiding power, good gloss retention, high tensile strength, relatively high percentage elongation and high distensibility. The film should retain some elasticity, have high surface hardness, high shear hardness, good adhesion and high abra sion resistance The pigment should be capable of chemical combination with the reactive acidic components of the disintegrating vehicle to stabilize the film Such a pigment should pref erably be of relatively fine particle size and impart chalking characteristics as the basic method of film deterioration The pigment should not only impart these characteristics to the initial of reactivity thereby aiding the reten tion of distensibility. Hardness of film is desirable providing distensibility is retained. Hard distensible films usually have better abrasion resistance and maintain better adhesion. In this senes of tests, those Alms with the higher surface hardness were associ ated with the better gloss retention. It is evident from this correlation of physical properties why house paint formulations must be well balanced with respect to the pigments used High quantities of zinc oxide would reduce the distensibility with conse quent loss of adhesion and would In crease the water sorption and have a tendency toward high reactivity and embrittlement. Too much titanium dioxide or magnesium silicate would reduce the water resistance, increase the water permeability, speed the rate of chalking, reduce the reactivity and thereby soften the pamt film to such an extent that erosion or washing would take place Excessive quanti ties of basic lead sulfate would reduce the reactivity, soften the film appreci ably and reduce the adhesion Increas ing the quantity of white lead is the safest way of varying the average house paint mixed pigment formula. It is definitely better than making additions of basic lead sulfate. How paint film but should retain these prop ever. straight white lead has a slow erties for the major portion of the life chalking rate during its early life. 102 .American Pairtf Journal 0O07-SV1P-043302 0007-SWP-000126649 which delays the "self-cleaning-*' at the surface. From the physical property stand point, it is expected that the present average house paint formulation will persist for some time--at least until the properties of the various pigment components are altered or improved, to allow larger amounts to be incor porated with safety, or until new pig ments are marketed that effect a bet ter compromise of physical properties. It is realized that this physical prop erty study is only a start on a tre mendously complex problem and must be continued to include various mixed pigment formulations and painting sys tems. The correlation of results on mixed pigment paint films and paint ing systems with the results obtained on the single pigment films should be helpful in the development at better paint films for the paint industry Acknon ledgment The authors are indebted to Alex. Stewart, director of Research, and F. J. Williams, technical director, for their advice and guidance during this investigation and to members of the laboratory staff who assisted m vari ous phases of the work Literature Cited <1} Racers Manual at Industrial Chemis try. Sixth Edition. Volume II. C C Furnas, Editor. Chapter 26 (2) A E Jacobsen and W F. Sullhan-- Centrifugal Sedimentation Method for Partide Size Distribution--Jnd and Eng. Chem. An. EMI Volume IS. No. S. Page 360. 1948 * <9> National Lead Company Brochure-- Normasal <4> F J Williams and A R Pi trot--A New Pigment Concrpt Presented at the Fall Meeting of ACS 1947 <5> E J Dunn. Ji . and C H Baler-- Applicator for the Preparation of Uniform Paint Films--Ind and Eng Chcm . An Ed Volume 13. Page 427 1941 (6> R S Hunter--A Multipurpose Reflcetometer. J Research N3S 23. Page 381 (3940J R P 1345 (7) H A Gardner and H C Pn ks--Sci entific Section Circular No 26G April. 1926 (8) G G Sward An Improved Hardness Rocker--Scientific Section Circular No 610. 1937 Paint and Varnish Proceedings Scien tific Section (9) Taber Abraaer--Instruction Manual V-100-3Q9-156-4S Revision VU 1945-Cour tesy of Taber Instrument Company (10) H. G Arlt--Study of Conical Mandrel Test (or Attached Lacguer Films--A STM Bulletin, December 1937. Page 6 (11) New Fork Faint and VarnUh Produc tion Club Technical Committee Permeabil ity Measurement. January 1, 1938. Paint and Varnish Proceedings Scientific Section --Following Page 187. (12) E J. Dunn. Jr --Chemical Reactions Jn Metal Protective Paints, Symposium on Corrosion Resistant Paints. Polytechnic In stitute of Brooklyn. Kay`4. 1946. i. .PRODUCTS Eq u ip me n t APKTHALIC aikyd resin, which Is said will not haze in the presence of zinc oxide, has been introduced to the market by V S Industrial Chemicals. Inc. 60 East 42nd Street. New Tork CKy 17 Known sn "AROFLAZ UM-M/' the new aon-haxing resin permits for the first lime mlrrorllke finishes, with hlgh-gloss and gloesletentlon, even In the presence of line oxide. The product, according to the man ufacturer. Is applicable for formulation of architectural paints and enamels, especially for use in mill whites for textile mills, and for all maintenance finishes Aroplaz 1248-M is a pure, long-oil, oxidizing aikyd supplied at 70 per cent aollda in mineral spirits, and Js the result or years of testing and development by U. S I *s laboratory and production experts Excellent film characteristics, and especially color-retenhon of the Inng-oli architectural variety, have made aikyd resins highly desirable for top-grade white enamels Characteristic weakness of alkyds up to the present time. U S I reports, has been their tendency to develop a surface haze giving the ap pearance of a thin Aim of chalk This hazing tendency resulted In diminished gloss to the point of almost appearing flat when viewed at normal angles, and It was particularly pronounced when zinc oxide was used in pigmentation As zinc oxide is absolutely essential to pi event yellowing of white enamels hazing has been a serious drawback to live use of alkyds in such enamels Specifications to which Aioplaz J348-M conforms an* a follows Non volatile. 69-7J per cent, salt cut. mineral 104 American Paint Journal 0007