Document zogNJmdEwndn1XpD7xL5qDy6a

IJL1 FILE NUMBER 2 5 VOLUME 8 NUMBER 1 iintnwmmihimMrmiiujinMiiiitiMmmitiNttmin'RiiHMinmiiiRKi NnnianMHiiiiiMiHMnitNHtniHUiiiHiiHmiHiiftwnKiniiinmiiuHvnHiiiiiMHtiiHuiimiiHflmitHtiiHNiiunHnMiNiMHmriii^numtiiiMniniiiitmiaiui INCREASED RESEARCH ON HOUSE PAINT PAYS OFF IN COATINGS WITH LONGER SERVICE LIFE Review Shews How Better Understanding of Complex Weathering Process Determines Most Effective Pigment Combinations o me o w n er s are benefiting1 from caily as well as physically in a protective H healthy competition within the coating film, pigments now can be pro paint industry to develop exterior portioned to meet specific requirements house paints that stay whiter, last longaetr will. and are easier to repaint, Sidney Wer- Meanwhile, a better understanding of than told students of the class In paint how raw and heat-treated oils may be technology at Wayne University, Detroit, combined more advantageously in prac Michigan. tical paints has had Important conse Mr Werthan, quences. Heat-treated oils, which have member of The larger molecules, are slower to disinte New Jersey Zinc grate during the weathering process and Company's paint permit closer control of the penetrating research staff, properties. points out that, Some of the pigment building blocks while no one pig* are more Important than others, but all mem combination play essential roles in meeting combined has met with uni* technical requirements and consumer versa! acceptance preferences. In a detailed analysis pub by ail paint manu lished In OFFICIAL DIGEST of the Fed facturers. general eration of Faint and Varnish Production agreement on cer tain formulation principles has re* 5. W *rthon suited in a rapidly increasing num ber of paints that give the consumer better service. Clubs, Mr Werthan reviews the methods paint technology has used to translate the findings of fundamental research on single pigment paints into practical coat ings based upon combinations of chemi cally active and chemically Inactive pig ments. Nl M90HI* HIDING NOW Although these single pigment paints described by Mr. Werthan and reviewed betow are for the most part impractical In themselves as coatings for the con sumer. they disclose the essential strong points and weaknesses of each base ma terial, thus paving the way to selection of the best combinations. Titanium dioxide is valuable in paints f Continwed on next pnytri FORMULATION TRCNDS Compared with prewar formulations, many of the 1940 products rate higher in hiding power, are lower In lead content and are based upon vehicles that contain both raw linseed oil and heat-treated oils. The outlook U for a continuation of these trends A more exact knowledge of how pig ments and pigment combinations func tion in a paint film Is ihe outstanding accomplishment of paint technology of ihe past decade, according to Mr. Werthan Seen In their proper perspective as building blocks which function cheml* Through displays similar to thirt paint dealers and the paint industry are stressing ralum of planned pointing programs. L.> f 0007-SWP-04 3918 N23309 HOUSE PAINTS (Continued from page V for its high opacity and chemical Inertn9* Emphasising the present impor tance of opacity to the consumer, Mr. Werthan said "When lead and zinc oxide were the only available white hiding pigments, two or three dollars paid a painter for a day labor and anything lest than three coats of paint was heresy Sufficient lead and zme could be put in white paint to provide ample hiding with three coats. But today, when two-coat painting is general practice and even one-coat paint ing i* being promoted and painters re ceive as much by the hour as their grand fathers did by the day, the opacity ob tained with lead and zinc must be rein forced with higher hiding pigments such as titanium and zinc sulfide/' SflF-ClIANING COATINGS Two crystalline forms of titanium dl> oxide -- anatase and rutile -- are avail able to the paint industry. Both provide only limited protective action for paint oils and must be combined with chemi cally active pigments for best results. Because anatase titanium does not form a strong mechanical bond with the vehicle, paints based solely upon this pigment weather too rapidly by chalking and erosion. However, this proeess, when properly controlled, through use of zinc oxide. Is largely responsible for the "selfcleaning" properties of present-day coat ings. Rutile titanium pigment films erode at a slower rate, and do not stay as bright as anatase. As with anatase, the mechan ical bond between pigment and vehicle is weak. However, rutile is superior to anstase for making tinted paints HOMtTICS OF ZINC OXIBK When a paint Is exposed to weather, the vehicle is under attack by destruc tive ultraviolet rays in sunlight. Unless checked, these rays produce progressive oxidation and disintegration of paint oils, Mr Werthan said Fortunately an effec tive barrier against these rays is avail able in zinc oxide, which is unique among white pigments in being opaque to ultra violet light. Zmc oxide also boosts the resistance of paints to unsightly mildew growth, Mr Werthan went on. A reaction that takes place between zinc oxide and cer tain vehicle constituents results in burrshaped soaps These burr-shaped soaps form strong mechanical bonds that rein force coatings. However, paints com posed entirely of this pigment are too tough and glossy to permit chalking and erosion at the desired rata Where traces of acidic gases are pres ent In the atmosphere, surface particles of zinc oxide present in house paint films tend to form soluble salts or soaps which, with rain, act as cleansing agents Present-tlay erfertW Jmne points, "fl/' slay cleaner. lease a sound rr foundation for repaint Jtftts than coating*, of former year*. Ufagtofied cmnnsectmn dron ing* the weathering process are from The New Jersey Zinc Company's motion picture, "The Pasnt Film.** Lead pigments have declined In impor tance as white hiding materials. Today, their chief value is in their ability to form reinforcing lead soaps by reacting with paint oils, Mr. Werthan reported. These eoape are softer and more plastic than zinc soaps. Lead pigments are Introduced into ex terior house paints either as basic white lead carbonate or as baste sulfate of white lead present in leaded zinc oxides Because they are darkened by sulfide fumes, lead pigments are not used in modern "fume proof" paints. White lead sulfate films are weaker than those of basic carbonate Although they do not develop the visible checking (Continued on page 8) PACE 2 PAINT PROGRESS 0007-SWP-043919 0007-SWP-000127269 I iContimted from page 1J dioxide pigments. In the yellow paint*, highway engineers who are not abLe to Pigment combination* used in the varying ratloe of llthopone. with or with* visit the seene of these tests. I white paint* included varying percent out sine oxide, to yellow pigment are be To supplement the Route 309 programs, ages of zinc oxide in zinc sulfide end ing studied. tests In thirty-two states and sixteen Utanlum pigment points: comparisons of Throughout the duration of the road cities, either directly under the supervi various grades of llthopone; comparison# testa periodic ratings of the stripes for sion of New Jersey Zinc Company Inves of llthopanc, titanated llthopone end be* surface dirt collection, color change, tigators or in cooperation with Interested riurn-base Cryptone*. wear, and day and night visibility are traffic departments, have been conducted Also, comparison of uttue, rutile, be obtained. Improved photographic tech la pest years to "prove la" formulations Hum-base, mad calclum-bsso titanium niques play a vital part In recording re on other types of surfaces, such as bitu sults for future study with results of past minous paving, brick, oiled roads and * Reg. Trade Mark. years, os well as for demonstration to even granite block surfaces INCREASED RESEARCH ON HOUSE PAINT PAYS fContinued from page BJ characteristic of the latter, failure to the wood is more rapid due to an eroding process that takes place. As a result of this process, exposed layers of film Rake off in tiny particles, taking surface dirt with them. Zinc sul/lde pigments weather by grad ual erosion and possess good cleansing properties. They do not react chemically with the vehicle. However, they are "oleophilic," which mean# that they form a good mechanical bond with oils. Xa white paints, the discoloration of the film caused by copper metal Is more severe with zinc sulfide than with other whits pigments. Zn tinted paints, zinc sulfide pigments rate second only to sine oxide In tint retention, Mr. Werthan de clared. Extender pigments In genera) use In clude siliceous Inerts -- fibrous magne sium silicate, mica and silica -- as well as calcium sulfate, and several type* of calcium carbonates. As a group they are chemically Inert, except that calcium sulfate and caieium carbonate may show some soap formation. They lorm weak mechanical bonds with paint oils. Modern paint formulation recognises these products not only as aids in adjust ing paints to correct pigment volume when high strength opaque pigments are employed, but as materials useful In themselves for modifying the weathering process In the direction of erosion. Mr. Werthan reported. This Is particularly true of fibrous magnesium silicate and waterground mica because of the rela tively large sizes and shapes of their particles. MICA HAS IPIdAL PUCI Mr. Werthan singled out water-ground mica as an extender pigment that war rants separate consideration. "Like other siliceous Inerts.'* he said. "It develops practically no hiding end produces weak Aim*. But because of Its thin laminar particles. It apparently protects and rein forces the film. While other Inert-Unseed oil (single-pigment] films disintegrate within a year when exposed to weather, the mica film maintains Its integrity for several years.'* Although a mass of information has been accumulated regarding the behavior of individual pigments, there is no one neat solution when It comes to balanc ing the good and bad points of these pigments Into mixed paints for the consumer, Mr. Werthan emphasized. Whether a paint is to be white or tinted has an important bearing on the combi nation to be selected. The type of service alto has to be taken into account. So do such factors as ease of manufacture, stability of paint In the can during storage, at; well as consis tency, brushing, levellntr, drying, opacity, gloss, color and others. WHIVIS AM* TINTS ( Tha most popular whits paint formula tions today contain a combination of nnVrtt titanium dioxide, while lead, zinc oxide and extender pigments. Fume-proof white paints consisting of titanium di oxide, sine oxide and extender pigments are growing In popularity. In tints where a higher degree of chalk resistance may be required, instead of anatsae titanium, rutile titanium dioxide or a zinc sulfide pigment may be used Good tint paints also are prepared using white lead and sine oxiide as the opaque white pigments. PAGE 8 PAINT PROGRESS 0007-SWP-043920 0007-SWP-000127270