Document pp0NB2dz7ke31QGwpMbN6ebMD

0007 -SWP-0000Q72S1 . -, --xxiX&Biprtr** 0 007-SWP-00000 7 2 63 '..: ', - : m&m : :rj *' ' :. ''"r^y/:.**T* -fj ; ; : Crude Materials for the Paint Manufacturer zinc and lead--oxide of line and carbonate of lead. Both are o generally well known, that it seems superfluous to do more than refer to theta, but this booklet would be incomplete without, at least, a cursory description. CAJtSOKAXX or l x is The term "carbonate" of lead is not strictly correct, as a carbonate by itself would be too crystalline in its structure to be of use for paint. In composition, it is both carbonate and hydrate, or hydroxide, and for a perfect product it must be combined in definite proportions. The recog nised chemical formula is S Pb CO, Pb H,0, (two molecules of carbonate to one molecule of hydrate, representing TO and 80 per cent respect ively). If much more hydrate than this, the opacity is reduced (requires more thinner), and if much more carbooatt, the binding and work ing property is impaired; it is difficult to break up, covers poorly sad chalks rapidly. However, a composition of 75 per cent carbonate and 88 per cent hydrate makes, a good workable lead, more especially if of reasonable, age--say six months. Under, favorable circmnstances, one hundred pounds: of tbe metal will yield eight-five pounds of corroded-lead, but thegenera! ran is about - seventy-five.; The metallic or blue lead must be pure oat ooly deatlverited, hut be free from all other mctals--eiac, bismuth, copper, etc. If there is a trace of silver, the product will have a pink 8 T'-MifeS^iecirwSMv' *' C'fvh -rtcsT-Sr>ri> "KtMSfei ,T'*i5Siy'i *` * ,;.y*Sv'1Vi*. * -<y 0007 -SWP-000007264 - -4.V.WI .W. Crude Materials for the Paint Manufacturer cast, and a very small amount of iron would five it a brownish tint. The term "old dutch process," as applied to OI,B d u t c h the corrosion of metallic lead is well known and explains itself, but it may be said that the excel lence of the product is largely due to careful and intelligent handling. The metal is dissolved at a low heat in kettles and is discharged into a box by an endless chain which carries perforated cir cular discs, technically called "buckles." These buckles may be or )j-inch thick and weigh up to one pound. The corrosion, as you know, takes place in stacks and the requisite heat, etc, is gen erated by spent tan bark. The acetic acid as pur chased is the commercial article, generally known as No. 8, which contains 28 to SO per cent of gladal acid (the standard) which is reduced to the required strength, each manufacturer having his own "rule of thumb" to determine just what that is. The method of procedure is to lay the buckles on the inner,projecting'parts of the and crocks (which are much like flower pots in ap pearance) so that the metal does sot come in actual contact with the vinegar.'- On the top of * a row of crocks boards are-laid., and on'these boards the tan bark.is spread.-Then a new layer of. crocks is placed and coveredthe!tame';way,.. and so on until the stack is full,jhe walls,being filled in with old tan bark to help decompose the - ' 9 \-e ,v fStT: * . . r'* .* *: 1$ 0007 -SWP-00000726: SB ' ":^-rr Crude Materials forthe Pamt Manufacturer new in the beda The beat of the tan bark gen erates carbon dioxide and volatilizes the <-vt which attacks tfaebuckle from the ontside and gradually eats inward. The buckles swell up" wards, so that when talcen oat,tfcey are fre quently twice their original thickness. A certain heat most be maintained in the stack, or much of the metal will be ancorroded,-and if ; there is an excess of. heat, the prodnctiwiQ be' yellowish. Ventilation - is seenredby a square hollow shaft which is: carried; op'from each, layer to the top of die stack. The confrnementof the. n metal within certain limits .'during^ corrosion makes a definite molecular structure impossible, ..and the product is ^amorphous. - The stacks are opened at the expiration of ninety or one handled days and the lead taken from the crocks.: It is ' then seen that only a certain percentage of the! blue lead has been folly corroded, mid separa tion is necessary. This is accomplished by means of a "separator," a description of which is un necessary. It does the work effectively and the uncorroded part is either sent back to the stacks or is subjected to calcination in furnaces for oxides of lead. The final processes are screening, washing, free of acid, grinding in water, floating in tanks, and drying in copper pans for its ulti mate grinding in oiL Any lead imperfectly ground in the water will 10 0007-SWP-000007266 is i'X" i. - :- ^->>':;--r:; jy*sr-- . vsp/fcjey. - CrudtMaieriaU for tht Paint Manufacturer ia.il to float. This is known as.the "core" and is usually calcined 'for the better class of orange mineral. The "palp" process, about which so much has been" said, 'is", simply feisii 'Whea','the' lead has passed through the last floating' trough, it goes into an upright tank fitted-with mixers, which are started'up.and the. oil-added.; The miring continues until the oil is thoroughly incorporated and the water expelled.nThelead is then run into kegs without grinding.:^A':inaU per cent of the watercertainly remains.-;'-There are many rea, ^ sons which!. we` could,'mamejirity. this process ."^should be condemned, bite,so fir as .we know, it fis not now generally in use-iTt probably was origmated from humanitarian,'rather than economic motives, for there isno^disguisng;.the -fact that the removal of the boncdry'lead -fronrthe pans is a dangerous work for employees.'~ J ^ In speaking of Old Dutch Process we are accustomed.to think that Corrosion of Metallic lead by Acetic Acid originated with the Dutch, but this is not the case. The principle is not less than two thousand years oid,'although of course methods were very crude. We know for a cer tainty that Earthera Crocks were used before die Christian Era. At least we have it on the au thority of Theophrastus (and no doubt of others) who explains that thin pieces of metal were placed in such vessels containing vinegar and 11 * -%>; B 5 .n-TsS'SSS S^us-StS*: it-- 0007-SWP-000007267  :":r '*-: -5i: - -'vf: ;? ..' j' ' _/ ; ifefSSSiSS that the corroded part was removed at intervals, etc. Now if it is considered necessary to mould pig lead in small buckles to facilitate corrosion, it stands to reason that other methods whereby the . metal is run into ribbons, or blown in a fine spray, cobweb-like, etc, will reduce the time very considerably, and so we have what is commonly spoken of as "quid: process," the most conspicnous of which is probably the "Carter Co.'a" who: disintegrate the melted lead into small particle^/ by steam blast and accomplish corrosion in-cham bers. AH quick process leads in fact are: made, in chambers or rooms, as distinguished fromstacks, but the; same ^elements are required for.: corrosion, and :the nearer, the product approxi-' mates to a perfettly made old dutch process lead, the better it will be. .:.. ------- The three indispensables are acetic add, car-' bon dioxide and moisture. Pure lead paint willlast jnst as long as the oil binder and no longer. When that is gone, the lead flours. There is no getting around this fact! We grind lead only to thoroughly incorporate the oil. If not made fine before drying, it can never be ground.fine. Too much milling destroys its oparity. As white lead is easily affected by sulphur, it is evident that no pigment containing sulphur should be mixed with it or used for tinting. m  . pg&y. -:: .ov*: :>*.!. vyvy:> ' Crude Material* for the Point. solution of basic. lead acetate (litharge dissolved in hot acetic add) by sulphuric rH In this way, about *50 pounds of the oxide requires 160 I pounds of die sulphuric add, which gives i yield of nearly 500 pounds sulphate of lead. The stronger add combining, rulessea the wester, so that the acetic add is washed away and lost UXBUIBS. Although the sulphate is hot in general ase, Ut19 die pigment known as-sublimed has a consider able sale. The principle upon which this article is produced may be briefly and yet comprehen sively explained as follows: When lead ore' (Galena, or native lead sul phide) is heated in a furnace with access of air, it oxidizes partly to lead oxide and partly to sul phate of lead, the amount of oxide depending on the amount of air which comes in contact with die lead ore. If this is sms11, then sulphate is mostly formed. If high, there is likely to be a decomposition to oxide and sulphur dioxide. The proper definition of the product is oxy-sulpbate of lead. It contains varying proportions of zinc, because lead and zinc ores are intimately associ ated and it is exceedingly difficult to wholly sep arate them. As a finished product, it is very white and fine and takes more oil than dutch process carbonate. From its nature, it is imper vious to gases, and so retains its purity of color under almost all circumstances. r+ s*fiar 0007-SWP-000007270 w i.- Crudt Mattrials for th* Paatt Memufadttrtr to ascertain tbdr proportional content of metal> nociM lie rinc and lead. They are then crushed and or aunnrionB screened by suitable machinery, sad the coatmhi- nted materials are mixed, also by machinery, is proportions that yrill jieVl the proper relative r- proportions of xmeaad lead compounds is the product The ore is now ready for charging; to gether with ai .sufficient quantity of fine coal to maintain, ctmifmstioiy-into toe ToartfTtring and . eroding "Theserfuniaces, devised specially for the jrar- pose, mie ao constrncted as to admit air to the incandescent mass of bre^and fuel an the grates in proper supply and"from all sides, - The zinc and lead present sre reduced to toe metallic stats and converted-to other volaiae forms, , but on reaching these conditions are instantly vaporized and drawn hyameass-of eahanst fans: into com bustion chambers, where: the chemical' traarior-_ matron of the product, dne to oxidiration, com pletes itself,. . "Thence toe. white fume passes forwards through a series of long-cooling fines to sus pended woolen collecting bags, whence the waste gases of combustion escape, while the pigment is retained. ' "The white pigment, as it collects in quan tity, is removed from these bags and carried to toe finishing furnaces, where on open hearths, 16 0007-SWP-000007272 i '-f- Crude Materials for the Paint Manufacturer A-ttmcAM produced by burning in furnaces, made of iron zmoa ai brick, with fire-bride lining, a mixture of fine coal and zinc ore. From this calcination, a Tapor.rarUe*, which, coming in contact with air, forms itself into the white powder, with which yon axe familiar. The;juniaces are heated and the grates covered with a layer ofifine anthracite iWben-feereoal; is bura.,,~~.geof ereand-coal, and sometimes limestone?-' isthrown oh- iti'fhe Mast is tarried an/gradually and after-half or threequarters'oif an hour, :the;charge is hot enough 10 reduce'and distiU some zinc which barns to oxide - with a green^flaaie.it 'fihe/opening at the top of the /furnace;whiai:llia'/jnnc..fiame - shows, fee damper in- thepipe'-leiding -to= the. collecting apparatus isopened-andtheoxide is allowed to go over. T:This<>damper ;is kept dosed while charging the furnace to prevent anycoal or ore dust from being carried over fee oxide. When fee furnace is hot'enough to make oxide, fee charge is partly melted and no dust can be drawn from it. The charge is occasionally raked, and the blast gradually increased, until nearly all of the zinc has been drawn off. The blast is then shut off, the damper in the pipe is closed, and the clinker remaining in fee furnace is broken up and raked put, fresh coal is charged and fee entire operation is repeated. The gases and oxide of zinc from the furnaces & m 5^|j " -O,-.;;'r-r-r'~r ^ -1;' .'.-..-jSVvAi - ; .. .'.'" 1- . - .-.x-z .. :- '>': Crude Materials for the Pamt Manufacturer other pigments without change tad tsfces con siderable oil to grind. The white ttt is com r'i-3 monly known u "Iithapone," "Pooolith," "Beckton White," ssd other registered names, is slso a xinc--a sulphide. Ussy year* ago, it eras imported from England under die came of "Charlton White," sad owing to its good cord ing power, it was. quite rxlmprciy used in com bination 'for `prepared ;house paint. . There was difficultyhoweycr^jaa maintaining a uniform - product and continuoussupply. This, with trooble in the manipnlatidnl killed it tad only daring viJ the past .dew; years Jtes =it been restored to a certain measure.cf. favor,-but it is now rarely used for.mixed paint.5The manufacture in this country is confinedf tp: two or three firms, and most. of. the. importation is from Germany. It requires expertJmowledge to handle it properly, andifoT:ubriot$reasbns,-it should be used only for interiorlworlt?although it is chimed for some brands, that it will stand exposure without change. Broadly speaking, it is a combination of sulphate of barium and sulphide of tone, pre cipitated together.- It. is conceded that for paint purposes it should'carry not less than 50% of the xinc sulphide which is equivalent to the imported Bed Seal. The Green Seal has (or should have) 35% to 40%; the Blue Seal, about 22%; and the Yellow Seal, only 15%. The process of making is more or less of a secret. 20 0007-SWP-000007276 --ys