Document Z4JLJqxKD1L0j8V8BBn64zbKV

DUP 000255 Making White Pigments HE first step in the making of paint Romans called it "ceruse" and made T is the selection and preparation of the pigments. Upon the care and it by exposing lead over sharp vinegar, which differs only slightly from the mod skill with which this is carried out de ern practice. Progress has been chiefly m purity, and more efficient methods of handling. The metallic lead from which white lead is made occurs in nature as an ore, which pends in large measure the excellence of the direction of greater fineness, higher must, of course, be mined and refined be the finished product. fore it can be made into a pig Paints are mixtures of solid ment. The ores of lead occur in particles or pigments and a liquid veins and pockets far under the or vehicle. Pigments are finely surface of the ground. They are ground metallic, earthy or animal associated with other minerals substances which give to paint which must first be removed. body, hiding and covering quali The lead is then cast into bars or ties, and color. The vehicle is a pigs and is ready to be made into ' liquid in which the pigment parti the white lead of commerce. cles are held in suspension, with The Dutch are credited with the object of producing a durable being the originators of the proc paint film, uniform in color and ess by which most white lead is consistency. made and which is called after In making a good paint many them--the Dutch Process. In different pigments are used, and it this process the lead is first melted is only by their most careful selec and cast into "buckles," so called tion and mixing that the best re because of their fancied resem sults can be obtained. One pig blance to the shoe buckles of ment may have good covering colonial times, but which look qualities but lack durability. much more like the round waffles Another may be much more dur of the present day. These bucklds able but lack the necessary hiding are then placed in earthen' jaife qualities. Still a third may have over a small quantity of weak the property of neutralizing ele acetic acid--which is practically ments in the paint film that our domestic vinegar. The pdts, would otherwise impair its stability filled with buckles, are then piled or shorten its life. The very twenty or thirty feet high I in highest order of skill on the part huge sheds in what are known' aa of the p&intmaker is required in "corroding stacks." Each corrpd- order to select and combine those ing stack, which is as big as a pigments best adapted for the house, is built up of alternate purpose. layers of corroding pots and sp^nt The oldest and most frequently tan bark, which is nothing mbre used pigment is white lead, which than oak bark that has been u ed was used as a paint material be in tanneries. - fore the Christian era. The A Modern CrmM U*d for Renoriiii Corroded I ood from (i* Starke In thecorrodingstaeks, whichkre i tnid * Corroding Stick DUP 000256 16 closed tizhr < mm pt hr -mull <'[*mnz- f0r ventilation. the tm hark la gin- to -lowly decompose and give otT carbon dioxide gas, which is the -tune thing that our lungs give off when we breathe. In fermenting, the tan bark also generates heat, which warms the acetic acid until it forms vapor. The vapor rises up through the lead buckles and gradually turns them white, for acetic acid has the power of corroding lead. It is the nature of lead to turn white when it corrodes just as iron turns red and cop per green. The white substance is lead acetate. But that is only half the story. As fast as the lead is corroded the carbon dioxide which is constantly being given off by the fermenting tan bark attacks it. A chemi cal change takes place and converts the lead acetate into basic lead carbonate, or, as we call it, white lead. The complete process so briefly described takes from three to four months. The stacks are then torn down and the particles of white lead ground in linseed oil. The resulting product is the finished pigment--the white lead in oil of commerce. The Carter, or. as it is sometimes called, the quick process, is also in common use for making white lead. Here the change from lead to white lead takes place in fif Du Pont Magazine teen day*, -o that there is a derided -avine in time over the Dutch process. In this process, the lead, instead of being piled in slacks, is powdered from the molten con dition and placed in large closed wooden r\ linders which revolve slowly. While they revolve, acetic acid and carbon diox ide are introduced into the cylinders and corrode the lead, converting it into lead carbonate in much the same way ns in the Dutch process. White lead, the most commonly used of all paint pigments, has the greatest cover ing power of any of the white pigments. That made by the Dutch process has unusual hiding power, while the quick process lead has better whiteness and spread. The best paints are, therefore, made by using for the white lead base a mixture of stack and cylinder process lead. Such paints have greater dura bility and combine the advantages of each. 1'nfortunatelv, white lead pro duces a rather soft surface in the com pleted paint film and it is turned black when it comes in contact with sulphur fumes in the air. It cannot, therefore, be used satisfactorily in paint without having another pizment present to count eract these tendencies. The pigment usually used in paint in April, Ills conjunction wi'h iuul i- zinc o mu ? This pigment lus been in use for onlv d-oui sixty years, but its use has assumed im portant proportions in 'lie paint trad.' Like white lead, it is made by two pro cesses. In the indirect, or. as it is some times called, the French process, the metallic zinc is subjected to extreme heat which converts it into vapor. The vapor or "smokp.'1 as it is called, is conducted through large chambers where the zinc oxzde settles in the form of dust. In the direct, or American process, the zinc oxide is made direct from the zinc ore, which is mixed with fine anthracite coal and charged in furnaces. The gases are conducted into huge bags or filters which retain the zinc oxide dust but allow the other gases to pass through. As a pigment, zinc oxide is very long wearing and has good covering power. It is second only to white lead in this respect. While lead when used .alone produces a film that is too soft, zinc oxide, on the other hand, when used alone, has a ten dency to produce a paint film that is very hard and brittle. These two pigments are, therefore, nearly always used in com bination with each other so as to counter act the defects of each and produce a wellbalanced paint. Sublimed white lead or lead sulphate, as it is commonly known, is also made directly from the raw ore in practically the same manner as zinc oxide. It has a fine grain and produces a film a little harder than white lead, but not quite so elastic. It dries very slowly, and, of course, this is a good quality for it pro longs the life of the paint film. A fourth class of white pigments are the leaded zincs, which are usually about half and half lead sulphate and zinc oxide and partake of the nature of both. They are made in the same way as sublimed white lead, by heating the ore and col lecting the dust in chambers. The leaded zinc pigments lack the covering power of white lead, but they are more durable and less likely to chalk. One of the newer pigments used in the paint industry is lithopone, or Beckton White, which has become exceedingly popular in the last few years, particularly for interior painting. It is a mixture of the solutions of the salts of zinc and barium. These are mixed together in the proper proportions in a vat, and the lithopone precipitated in the form of a powder. This powder is then washed, baked, and ground very fine, and it is ready for use as a pigment. Many other pigments are used in the manufacture of paints. The more im portant of these will be discussed in a later article. Lithopoo* Filter pTtMM Watch the Details During this period, when unprecedented activities are demanding the full tunc of even.' worker, many details are likely to go without notice. In many cases this may not have a had effect, but in farm operations neglect of certain details can result only in failure. This is especially true of orchard and garden pests. Many orchards appear to l>e healthy during the winterand spring months, but laterdevelop troubles of one kind or another that abso lutely ruin the fruit crop. The only guard against these troubles is constant spray ing. a detail which should never be neglected at any time. In the anxiety to produce the maximum amount of fo<xl crops, there is a likelihood if planting crops on lands to which they are not suited, or on lands that have already become sick of these crops, or that are poisoned or diseased in such a way as to make the crops unprofitable. This should he avoided hy careful rota tion. Only the l>est seeds should be selected, as faulty seeds cannot be expected to produce satisfactory crops. The little details of crop growing must !*e as closely watched by the gardener as they are hy the extensive farmer if suc cess is to be expected. Why Watte Time? "Why do you consider women to be superior to men in intelligence?" "A bald-headed man buys hi3 restorer by the bottle, doesn't he?" " Er--yes." " Well, a woman doesn't waste time on a hair-restorer; she buys hair."--London Passing Show. Held His Audience The Lecturer--There was one time in my life when I had no difficulty in hold ing an audience. The Sympathizer--When was that? The Lecturer--The night I proposed to my present wife.--Answers Spr,,iBf th Only S.f.cu.rd Af.iiut Many Orchard Pert* DUP 000258 32 Du Pont Magazine April, 1918 iH mmnnmn DU PONT AMERICAN INDUSTRIES r:j]liIGDEIu jinn! For the convenience of buyers considering the purchase of any Du Pont product, and desiring specific information, this coupon is printed. Upon receipt, it will be forwarded immediately to the proper office for attention. Fill in, Cut Out and Mail This Coupon <Du Pont \pr. 'IS) Sales Promotion Division Date E. I. du Pont de Nemours & Co. Wilmington, Delaware EXPLOSIVES 3 Farm Explosive* 3 Blasting Supplies Industrial Dynamites Blasting Powder O Permissible Explosives 3 Road Building Clay Mining Land Clearing 3 Tree Planting Charcoal 3 Wood Pulp SPORTING POWDERS 3 Hunting 3 Trapshooting 3 Black Sporting Powder Smokeless Powder 3 Hand Trap 3 Rifle Smokeless Powder 3 Pistol Smokeless Powder 3 Resort Shooting 3 Shooting in Colleges 3 Shooting on Boats Carpolene (Wood Preservative) a Wood Oil Dead Oil Belt Cement Household Cement Blanc Fixe q Solvents Leather Substitute Solutions Split Leather Solutions Patent Leather Solutions Colte a Belt Cement 3 Saltpetre 3 Refined Nitrate of Soda PAINTS 3 Town and Country Paint 3 Colon in Oil 3 Virrolac Varnish 3 Virrolac Stain Finish 3 Flowkote Enamel Dulite for Mills Antoxide Iron Paint 3 Shingle Stain 3 Auto Finish 3 Sanitary Wall Finish 3 Bridgeport Standard Paint 3 Wheeler's Wood Filler 3 Bridgeport Wood Finishes CHEMICALS 3 Acids 3 White Lead 3 Alums 3 Lithopone 3 Litharge 3 Rubber Makers White 3 Dry Colors 3 Pulp Colors 3 Salt Cake 3 Barium Chloride Distilled Water Bronze Powder 3 Bronzing Liquids PY-RA-LIN Py-ra-lin Toilet Goods Challenge Cleanable Collars Novelty Sheeting Transparent Sheeting Py-ra-lin Rodj and Tubes O Py-ra-lin Pipe Bits O Py-ra-lin Specialties Brushes Q Mirrors Combs Toilet Sets Manicure Sets a Desk Sets Colored Sheeting 3 Smokestack Paint 3 Floor Varnishes Wood Lacquer 3 Metal Lacquer COATED TEXTILES 3 Floor Paints 3 Waterproof Cement Fairfield Rubber Cloth 3 Enamels 3 Py-ra-lin Enamel Rayntite Top Material 3 Concrete Paint Pontar O Motor Fabrikoid 3 Marine Paints Pontoklene Craftsman Fabrikoid 3 Industrial Paints 3 Pitch Truck Special Fabrikoid M 3 Railway Paints 3 Ferro-Keep (Metal Paint) 3 n Pegamoid Aluminum Mantle Dips Paint Marine Special (U. S. Standard) Q Shoe Special 3 Bam Paint Leather Renovators Book-Finish Fabrikoid 3 Wagon and Carriage Paint Ether Fabrikoid Sheering 3 Auto Paints and Enamels Parlodion Home Uses for Fabrikoid 3 Decorative Stains 3 Nitre Cake Fabrikoid for Baggage 3 Varnishes 3 Creosote Fabrikoid for Upholstering Wire Screen Paint 3 Shingle Oil' Rug Anchor 3 Japans E=3 3 Shellac 3 Pyroxylin Solurions Benzol Products Hat Sweat Material Buggy Aprons 3 Red Lead 3 Carpo (Metal Paint) Fabrikoid for Railway Cars Name Position Your Address (If Personal) ................................. Name of Concern (If Company) .................................. Address of Company .............................................................. BUSINESS : Z Manufacturer; Z Producer; Jobber; Dealer; Z Consumer. (Check which) What Du Pont products do you sell'1.............. .................................................. If a user, for what purpose does the product checked, or that which you now use, interest you ? Specific Questions Should Be Asked In An Accompanying Letter ! I?11 miiiii!!'iTinrTTi!r'iT'iiiiTrii!!':''4j rrrmTrfTrnTir DUP 000259