Document KJ9vyGnaNxR7pyMp2o40zYoeN

^ ! ^ f* r*; "n O [`ss^sss JF M^ES . THE ASBESTOS INDUSTRY A :|f By Oliver Bowles \ ,T ;-C :ncz ..... -up .roer. ::m: 11 < >?'. ( in- -- ; >: >i t : o- c-> ii i-,-; * ,,f u i nit Lit-:;: > i! * -irand- ,-s;;uihn:,' \vn- :hiii u.:1; in wail. except here ::i i. 11 ni in1 mii:;;;! -*'U ills. N ! o-l Ciinil'li'i'r'.li iir' II .ill - of ehrY-ol lie. ;1 ilii iSil > , .it id rrnrii mi: 1 , ;i it- of ini- 1ml :: 111 11 < > | )i i \ !- ;ne r<-*s . if ever. occurs m her vcni'. !;i -bp-fiber i '<;> -- i i - dir strands more or ir-s 'i:iruilr'i dm Vein wails. They Urqnrmly show :rkr nsii ;'.-i i s 11 rfa ers ! irc:i i ise ! ]u*\* occupy shear /.ones where the ruck has 'uccll Subjected 'n ;i!! i v i'i i i.n I ::nd , JMi' 'v,i!i ...n't' i rniiuwoti :n tin- r: u'im ; \ ; i i'i on mi m i m i rs .11 ;ie::r .'.urn, i :!!.'< in v:! 11 r* lie! )i i-i i - : 11 r Bedford ami ! v < Mnuiit. \;i. In n in ---i i: irr o.-nosii- : in .v :s no i > 11 >: i f oru'iii ;il mu ni fiber- ,\!;nni : i .' mitre ma -- of llic is Minn!><i of i111t1113of or MrrtUrs I hat - ni id :nii- -iimV <I l:i I! 1 o' >t mol lire. ! h is i j><* uf Denir:'<*!ic:* ;s emulneti iilninM rxeinsivrlv !o the a li diooity :lit c Yai'ie'V mnl IS Weil exemplified h\* deposits 111 1 lolly. wiHhI mill Buck Mouniom. (in.. and Kantian. Idaho. PHYSICAL PROPERTIES "I3RCUS CHARACTER r'.xperinieiils liy Kay iie-*i o^.-\ianlia11an. Inc., T!.<- <m t-I:: nd i ny 1 >1 j>ira I . |i:i nirt rri>l ir of in I'.bVJ on samples ,,f Khode-ian riirv^.i)lie. one dark wiiii a total iron rontenl of J.-tsii pei-eeni asbestos is ns fibrotj.- >l ruci mv. Ollier iiii* : n i r i .*i 111 libers fniimi in nature hit those ol and one a liyht type with totai iron. iiis- rio-<-d that die darker mainuai rei'iuifes much annual origin. such as wool mnl silk. :nnl those of vryet ,-i I .ii* i infill. e\a m pir> of winch an- niiimi mnl !!a.\\ ,\ oidla in tin: hilii y is mtc of tin* more time ami eneryy to liben/.r tiian the lower iron t \'[*e. ^1 lie Use-, in w !u<dl a clirvsil sir :isin*sl.)S tn.1V strikiuy differences between aslxstos ami the he applietl an* yoverned pnmarilv hy lens'll] of fibrous products of animal or vryet ahlr oriyin. filler. '1 he Imtyest fillers roiiimand the hiy!*st i ( B perhaps eoun! iinnorlanee is the difference prices, and prices an* proyn--ivclv lower for the to -l rue) nn*. Knelt filament of eotton. Wool, shorter yratles. !l is apparent, therefore, tltal or <ilk is of measurable and fairly constant primarv aiteiidoo must b* ^i\.ui to miiliny liianiHrr an<l is indivisible into finer sizes. prneess<*s dial Will Separate tile ftiiers from the On the oilier hand, fillers of ehrys>dle ashi*sios parent nick and will fiiienze dnun adeoualeiv ran he iii\uled and subdivided until a lufrurs- with a iiluiinitim of liber breakaye. C :> attained dial is liniiletl only by [lie delieaev of the maehinerv used and the skill of manip COLOR AND LUSTER i ulation. The ultimate tiher size is pnstnnalilv die -ize of the ultimate moleeule or rrvstai (.'hiwsoii!e oeeiirs in various shades of ^reen lattice of a>lu'Stos. in other words, tilieri- or Ve!loWls)| ^!*<*eti. \\ lien !ibi-i i/'-d into a zaiion h a eieavaye proeess. ami eleavaye in fluffy mass. ;I11 iy|>es of ehry-oi ile are \tmiail v intnera!> delined n> a tendeneV to split in a winle. nnh-ss si ainetl 3n* impurities. Amnsite eertain direetion. dial is. hi separate alony and ra.nyes from yra \* or ve! I o wish yra \ to wit u <* a mi. I1 between la vers of UHiieeuh'S, . From the standpoint of use. filler size (diam if rein: 'Vrl v [Hire, is while when ft 1 lerized. (`iT>eiiii id 11- is lavender bine, and tins.color is i eter: is important. and t he diameter will depend niainiaoi-d when tin* libers are separated. i upon tin* deyree of fiherizal ion ivttuimil in the miiliny proet*ss. Fillers ohuwitietl fmttt different Amliopijyllite and treniuiitr are yray. yreemsh yray. or white, and tin* separated fillers are deposits vary in tin* ease with which iliev mav while unless siaminy impurities are nn*s4mt. hr fiherized. '1'lins. two samples ofehrvsmile d'he luster of asliestos usually is siikv or peariv. J ai-liesi os. yi\-en e.Naet ly t he same mill I retit metn . may furnish products difirriny eonsiiicraldy in fiikw diameter, because one of them separates HEAT RESISTANCZ or liiierizes more easily than the other. Such Tin* heal ii-siviauee \>f aslu--ios is important i differences may lutve ejvnl praclicai itnpor- til uiauv a upbea: n n is. Some users of itsiie-los laiiee. iiecaus** an asln*sio Ijaviny diiiirull lent! lo confuse noullammahiiu v wttli refrae- ieavaye may require -.ueh intense miiiin" to iiinncs*. Many s;distanei*s tliai will not burn reduce the fibers to desirable fineness dial diev will, nevertheless, melt or defomnose at abu i mav lie l*rol<i*n into undesirable short ienydis. Base or diilieulty of fiiienzal ion is therefore an t i vely low tempera t ures. 'Hie fireproof [tmneri v of asiiesitiS i> one oi It- chief a--eis; n(lt. inqiortatH pruperty uf aatiestos. ahhouyii unimniable. it will tiermiipose aiui loss- 0 :.ionz OF uCCVtIF.ENCE : ecenhai phvdenl properties :if imuicrii I c! V '.vhieh adajit it for ma mifaet lire into eoverirv^s .11LTi <.'!)per::I:jres, ! concept of ;js|iesj i>> as that are nonenruiueiors of iie;H !):; u-e ! it fheir a ; i :irn i \** ;t! raei oi'V sid isl a nee has heelt created jjorous nature. !ji ; lit* Minnis <>i *ome 'undents of the subject f\* icrichiC tin* statement made hv {'irkel 1 [lull CHEMICAL RESISTANCE temperatures of L'.onn i,, :;.nnuJ [*. mv euUIv withstood. while with 'omr varieties a temper:!Hire of o.iinn ! . has appiireuliv produced no Tnmiolile and am hopiiviltte are hejiiiv n-d-taut to r i leii i lea Is, It i claimed that eroen loii | e vnuhlr eiFeets. M :t h <me respect to l)r. C'trkel. n-Asts rheimcals ami >eti water remarkanK* who wrote a. splendid pioneer volume on ;t Wei!. ('iuw-ol tie Is alTeeled more i'eadliv o\* :niner:il of which little was known ;it tlnit lime, aeals and oilier ehemieals than ere the amphi- lie was :n error np.::miihir (lie heal resistance of hole va i`ie! n*s. efir' ^oi il(*t Braudenhcryer and others : who have made ELECTRICAL RESISTANCE t 1 ;t comprehensive stndv of ! emperu I tin* effects of rhrysoiile at the M iner:ih:^ie::l Institute of ihe (.'niver-ity of Zurich. visile iit:ii ilte socalled nd-orm-d witter of ehrvsoiilc is driven oir at ;jhoil( oDO C. Between oAU and (>UU-` C. ::i 1 of lhe wilier of rrvstaiiizat ion is driven oif. and ihe miner::! 'raduallv oilers to olivine. A prononneeti change in phvsieal properties accompanies tljjs ileh Vilfilt ion. At 400 there is noi:ih!e del erinral ion in filter rpciliiy; ::nti shove .*.*0 ('.. with more or less rnmple+e deltVilrn I ion. 'itrvsolih* is completely decom \ari`ties of <-hrVs*uile lowest m iron eomenl are most suitable for rleeiri'ad uisulalion. Arizona ehrvsmile superior for lids use, Apparentiv the iron eonteni of amriidhole Urn-- not affeel its use for this purpose heean-e eroddolil e. u loeli upon analvsi- iiows a eon- lent of ahoill pere.utl !`e<). lias hivii eieetrieal resistanee. '1 lit-- '<`eminy eon; radieiion niav ! explainetl I * v* the fart that iron i- pi'estuit in enettM>liie as a silicate, where:)* m eiirv-oi'le it eonmionly appears as iron o\ide impurii posed. Ihe nmphihule varieties of asbestos will wil h*tand somewhat higher lent pent l ores SFECIEIC GRAVITY :ii::n eltrysoi tie; however. mieitUtiite. although The Speeiiic arm'll of [Hire eltrvsoi lie Is -.-'2. ) having a low water content. is easilv fused into hip that of tile ennimereud Irin*;- :dwa\'S a black. magnetic mass. 4 InHter )ieea>t-e of ihe presence of :mp::ril ies. Tlie >})eeiiie . ^ravit of (*anad:uu eurv-oiiie HEAT CONDUCTIVITY rattircs from 2.-'h to 2.*'.!: ami the Arizona iiher. Asbestos does not ha ve low heal eondlJetivit \. Its vaitie tor heal insulation is due to its noniiaiumaidiity and also to its fibious structure. I'iitii lower in iron, ha- a speeiiic gravity of 2.47. Tests iveetl 11V made !>y ihe Bure::;: of Mines al TniNiit. Ariz.. on ijin*r <*>!emed .vuli irreal cure to eliuiiiutle impurtiii-s ^av- some what lower liiTures--a 2.`N average for Arizona 1 fir !;>(. Vr::r. ClirvwiCl*- lr* Or*-iirrntM*\ V. ' I -.u<i I lh-e. Un, r.;,;:-U. s* .V,.. eiirVsol ile and 2.-IS mr one s;HI tpl. i rortl (v)ue! tee. 1 `a nal: 'rite s,,,., ili' yra vii \ ol a m hophyllii e r -- K.. K, W.. :n*<l N'isrli. I*.. [Tti- ranges from if. 1 io : . am:! tin:! c:if eri nut iol i i e * M u--iiN <r ]||* -- I; in~itr.. !> Vn:- ^ >1 xM'-lun. Ji ditnt. **!. .*. !!U7. |*e st ii! he:avier. r; ui^in mm -i to i l V. k, l'!i _. t :' i !` i Mi ? \ T 3* -I Il ii 5j* C` ; * 'i i1 <=.ff*i g ?' St* - r-: E, e. L . i !*1) 3 rot j s ;n:i ! rrial ;v<r!V)niir. g i'oi : on. silk, :>t* Avnui 'ml : ]\'.vini: ! ] k* ihhiimI f111:;ii;;- if 'ton- ,!.inn 11:;;! 1111 _V N,;l IsflC ! nuiiiii ill H' M * ** M | S *>0 ..Mill r:\ m \* : :;;H ii j < liiilictiil m H lit i *.: I ! - !*;i ` 11 r\* 4, ij>i !lUli> ' lUTl'i!OC. A si n Ji'l:: '^c of tw la ;1 51: one llrtvii V< ;or >< m i\ =1. i>>l im l OS. Urmia it v > v,r ;;; i i isolation from sources of asbestos iii imp AVorld AA'nr II prompted ;i gnat I heal of experiment I ion on 1 >o.-~.=i 1 >]o substitutes. Materials tested included glass wool. steel wool. iron wire. synthetic rub" ber, organic plasties. reilulnse. and treated paper. Some of ! isc so-called substitutes wen' so un- >.'i t isfari iirv I bat no further mentiou will be made of tiiem. Tbe world wide shortage of asbestos during and after A\'rrlil A\ ar II led to extensive research oil possible .'ill istil ulis in tbe t'uiled Stales and oilier 0011111 rirs. Con sideration is given to individual substitutes as fullo'.vs: ' SODA-LIME-SILICA-GLASS FIBERS The development of a fiber-glass industry opened up a promising field for substitution been use i^lass fibers, like asbestos, will not burn. However, as will be pointed out. later, glass fibers may lack pertain physical or chemi cal eharaeterisiics inherent in asbestos and consequently fail to satisfy the exact in 5 speci fications that must be met for most uses. For other usi-s they may be satisfactory. Glass and related fillers are manufactured in two basic forms--a wool-likc tiiatrria! and a fihunont. Kock wool, glass wool, and slag w ool are u.-ed primarily as lightweight thermal insulation, such as house fill. Sm-h appiir.it ions in general are not substitutes for asbestos. Glass fila ments made by more refined processes, involv ing the use of platinum dies, are of high quality and uniform size. Some art' less titan one-half micron in diameter and are adaptable to highly specialized list's. such as weavin'! into fabrics. Attempts have been made to use glass-fibers in place of asbestos in asbesins-cement products; but such lists have given imsaiisfacrury results, eliielly because of a eiicmieai reaction between tiie glass and cement, which deeoinjxisis tiie fillers and distrovs their elfective strength. Neither glass filaments nor cloth woven from them risists hit'll temperatures. The libers will not burn, but they will soften and coalesce when the temperature reaches a certain point, and this point varies, dependin'! upon tin- com position of the trlass. The organic film used on woven-glass lex-lib's will dcrom|Misr ami volatilize at about 000 ('.. and its loss impairs the elfeei iveness of the fabric to some extent. Normally, glass nsists weathering very well. '.Yin <iOAVp :1111s jcut;: i! V inw un vr::! iiP!*:n^ mIYc' 1 f'Vu-U ;i fl t T ! 11 :i 11 V 1' IC in'S nf M mv. CUT . ;!)< -K'! ;in ;irc:i ;)(* r mi! \'i 11 :;inr of vorv fine ' 1 i mts i'i -n ^1 l ;ii: M 'Kin !<urr in VHU T V n nor ru<uiis in rci all vc:y rupid aJI'I c I'ioni; inn. Glass and mineral-wool fibers are ,r. eient i hernial insulators in various types of (niip- metit. such as stoves and refrigerators. wiiere temperatures are moderate ami corrosive ron djtions are not encountered. The nigh tensile Strength. the creator thermal stability compared with organic fillers, and the elect rieal resistance of giass fillers make them suitable for electrical insulation, such as sleeving fur wire and tapes for the construction of some types of motors. Fiber glass is used to some extent in eunjune- linn with, or as a substitute for, asbestos m Navy cable insulation. It is claimed, however, l-bat asliestns insulation permits greater flexi bility in finished rabies than can be obtained with fiberglass insulation. Glass fibers are said to be unsatisfactory for cable filler mtaterial that fills in the spaces in a group of insulated cables), but recent, improvements in giflss fibers promise future satisfactory use. Aery thin glass-fiber paper may find adv.-mtngcous use in condensers for electronic, equipment; for in stance. its use may make it possible 10 reduce the size of the condensers. A giass-nsbesios cloth was designed during AA'orid A\*ar II to extend the supply of asbesto- textile fibers. It lias continued in use as a coverin'! on thermal insulation applied to pipin'! on naval vessels. It is woven with a plini yarn having one strand etu-b of glass ami asbestos yarn. United States Rubber Co. has announced production of a new fabric named ``Ashesum." consisting of interwoven glass and aslusto- varus. It is said to be well adapted for theater curtains'as well as for fireproof draperies in schools, hospitals, libraries, hotels, and ships.1 Coarse glass filters compressed inin halts arc eirieiem lightweight air lilters that are used extensively for cleaning large volumes of air. Asbestos is not widely used in this field, but blue asbestos has found important use in gas mask lilters. The Naval Research I-abor:iior\ has found that glass libers make superior gas filters. In recent gas-mask tests in a smoke- filled room, only 1 particle in 100,000 passed through the filter: at the same time, the mask caused no increase in normal hreatiling n-sist- anee. Glass filler paper is >.nd to he ".A.(Mill limes more elfective than present commercially I I'.kbl. p. I Gb.*.4 V*i. J], V'u. IfJ. 94 . .IS :t:;i i >ic fi i: !-r< " The .liler paper <:: s i In' iii;;<".itrd :n Oaragmnhs wnnih iu- ::i;n;r anv nriintarv : >:s f it will!. * i';! ><g: a>S ::w:v. ; iirrnnre. ui-iiJ.iee nine ::*><>e<l os ;il ,N;i\ V < I j i : 111 :: gruwing ;:! |)a < nil I v of Inc uaiu.-lry \o pl'm'-d'- fur prosper1 !\-(. fiWwrc .'weds. gas :V,;;-"o. ! i. iin> been rlnimi'ti. 1 itnve\ er. A. uue-tinn ha- bccti raised a- ;o die iimhn- !wi; nice a-ne-uos is inner -at isladnry '.Hiii? on libw-gia-s uianul'aenire ,mposc<i bv g::;< fiLcrs :or rjvnniii g::> nta-ks ;ml for iLo-c [In- for piatnuun. .U one stage ;n the ,;>eii b v I be A wnv. principal process of fibcr-gbi -- manufacture, .V vunsuirrabie pari of the pirx'i!l product ion the mniicn glass js drawn liirougji perforations of niirr glass is being applied to military use-, ,n a piaiinum-bottoined cell or busiiing. aiid .Many ni.-iminiri nrcTS of cleeine insulating it appears that no other substance <nm be materials are listed ns users of /i!>or glass. for stib-tit utctl for the platinum .o uveu'. iiM-nuse instance. mrtnufite'. diti's of asbestos eioili ;md piaiimun is jiroiluecd in ilntited f|uanihies-- lanes. laminairs. varnished :tiding. nuiguet- a world jirodneiion of about 300.unn trov 1 wire covering. and mica insula i ing products. Fiber glass was widely used during World ounces a yejtr--and has wide scientific and ino'wsinal uses, it.-, availabiiity for widi-r appli War II fur heat. sound, and electric insulation cation m tins industry des<'rves careful con on aircraft. Over f)0 percent of (hr out pul sideration. Platinum is a critical material dui'int: World W*ar Ii was used for military or during war periods. Three important cir assent ial civilian usr. cumstances tend to relieve, to some extent, the Tin* use of fiijt'j* glass ns a substitute for ihreai of a possible shortage. .isbesuw in motion equipment !ui>. in genera!, 1. There is very little loss of platinum during given tutsat jTfaeturv results. .\o published fiber-glass mauufact arc. The holes through information on eomparai ive icsts of liber glass winch the fibers are drawn will gradually and asbestos in brakebands appears to be* available, but verbal statements by those who enlarge, and the platinum bushing will neeordingiy have to bo rebuilt, using the same plat have made such tests indicate that the prin inum. Care is taken to recover any dust or cipal objection to liber glass is its rapid abra fragments of platinum. 'Die first installation sion of brake drums. is the important consideration, but subsequent As fiber glass ran replace asbestos in certain replacement of loss<*s is very small. fields of application, its future availability is 2. K>searrh is being conducted constantly to of first importance. It had been claimed, that find ways of reducing the quantity of platinum vise proves- of manufacturing liber glass is required in each bushing. Presumably some controlled bv a single company--the Oxvons- saving will he accomplished. Cm-ning Fibei-ghis Corp. Sueli a claim i$ not. '). Ki'Search is also underway on possible now correct. Glass Fibers. lnc.t Waterville, substitution of some less mstly and more Ohio, has its own process for making fibers abundant substance for platinum. Limited suited for glass-fabric manufacture. and Glass progress juts been made, anti there is ai least- Fioss Corp.. J^ong Island. X. V.. lias developed some promise of sueress. a process for making bonded mats and air Another raw materia] essential to fiber-glass fillers. In addition to these independent con manufacture that may he in short supply in cerns. the following companies operate under limes of emcrgcnev is cryolite, sodium-alumi license from Owons-Corning Fiberglas Corp.: num fluoride (Xar.AlF;l. which is mined only Gus?in-Bacon Manufacturing Kajisas City, in Greenland. The supply, however, is aug Mo.; Libbey-Owons-Ford Glass Co.. Parkers mented by artificial cryolite manufactured from burg. W. Va.; Pittsburg Plate Glass Co., Shcibyville, IiuL; and Ferro Corp.. Nashville, fluorspar. . If supplies of both those materials are limited, sodium siiienfiuoride mav be suIn Trim. stituted; but. as this commodity also is a de The parent company, Owens-Coming Fibergins Corp.. has increased its capacity greatly, rivative of iluorspur. it may likewise full in (lie category of scam* materials. it now has plants manufacturing fiber-glass L'mler normal industrial conditions the sup textiles at Ashton, 3i. IM Huntingdon. Pa., ply of both fluorspar derivatives and piaiimun ami Anderson. Pb C.. the latter plant came would appear to bo adequate for a moderate into production in July Iflul. The company expansion in fiber-glass manufacture. Most of also ita four plants making nontrxiile fiber the raw materials used arc. plentiful. e glass ttrudiiets. such as block ami blanket insulation and pipe covering. These plants arc at Newark. Ohio; Kansas City, Kaos.; HIGH*SILICA GLASS 5133S Santa Clara. Calif.; and Sarnia. Ontario. Canada, 'bhe expansion in liber-glass mauufact tire (Has- fibers appmximnting vitreous silica in eniniK i-tt inn are superior t> .-Mh:-lime--filieu - M (mi- III I'lllillC ItlMH'IlK.i MHI. I ><-tIlCIIM-lll I ' I U|.r-- i ilM-r vs... i.....t..>... ! ><*v*Ju4ant Ji*' N:ivui LairnCmiry: I H*c 7. JM.Vi. glas- fillers in resistance n> deioriomiiou from the action of water vapor and to high tempera- t ; trousrrtr - ;iiros, but their manufacture is a difficult prob enough `o justify commercial production have lem. Fused silica is so viscous, even at tem been established.* . peratures as high as 3,700 C., that its manu Both high-silica glass (quartz) and ceramic facture into titm filaments is almost impossible. (aluminum silicate) fibers have been used suc To overcome this high viscosity, fluxes arc cessfully by the Naval Research Laboratory, added, the floors are made, and the fluxes are Washington, D. C., for making paper that then removed. Several methods are used, but has superior properties for electrical insulation. they are similar in principle. First, filaments A regular papermaking machine can be used if . are formed from an ensily workable composition, the fibers are of fine sizes and properly purified. 1 such as an alkali silicate. Second, the alkali Quartz paper is said to withstand temperatures or flux in the filament is removed by leaching up to 3,000 F. and ceramic paper 2,500 F., _ or ionic substitution. The resulting fibers are whereas the upper limit of asbest-os paper is not ' relatively porous and of high silica content. more than 1,000 F.4 * They will withstand, with little deterioration, Hydrous calcium silicate is another insulating temperatures exceeding 1,000 C. The mini material used to quite an extent during the " mum diameter of high-silica fibers on which past 10 years, particularly as an alternate for data are now available is about 2 microns, and S5-percent magnesia where high temperatures . the average is much greater. On the other are involved. It will give satisfactory service , 7 hand, natural asbestos fibers are only a fraction up to 1,200 F. ' (c of_l micron in diameter. Correspondingly, the It was reported in February 1952 that Glass _ silica fibers are much less flexible than natural Fibers, Inc., Toledo, Ohio, had developed a ; ckrysotile. If finer fibers can be made by im- process for making pure quartz fibers in sub- _ rovements in processing, this difficulty may micron sizes. e overcome to some extent. Because of their high moisture resistance and ability to with stand high temperatures, the vitreous silica fila ORGANIC SUBSTITUTES . ments undoubtedly can be substituted for as German scientists attempted to manufacture * bestos in some applications, but it is doubtful van) using short-fiber asbestos mixed with that they can replace asbestos where flexibility long organic fibers such as cotton, cellulose, or or elasticity is a prime consideration- Further synthetics, but the product obtained was very ' more, the cost of manufacture is very high. weak.4 Cardboard with an organic plastic Dr. Rudolf Leutz claimed to be the inventor was used in Germany as a substitute for asbestos of a process for making synthetic asbestos in packing in flanges of steam and water pipes. , Germany. His product, however, could not be This packing was satisfactory for pressures up <r called synthetic asbestos because its base was to 5 atmospheres and temperatures up to 1G0 sodium silicate, and an analysis of the final C. It is stated that substitutes for asbestos in product indicated that it consisted of over 9" higli-prcssure packings have not been suc percent SiO*. It was, in fact, a silica-glass fiber. cessful and that all substitutes developed and Three companies were licensed to manufacture used up to 1944 were inferior to asbestos.7 this product in 1943, but because of the military A diaphragm of Perlou paper coated with reverses suffered by Germany no progress was barite paste was tried by I. G. Farbeninclustrie made.' * as a substitute for asbestos cloth as a diaphragm in a Siemens-Billitui cell in the manufacture- OTHER SILICEOUS FI3ERS of NaOH by electrolysis of NaCl solution. It failed within 30 minutes. Perlon is a German i A newJeries of aluminum silicate fibers, made synthetic flbci similar to nylon. However, a i by the mineral-wool process after fusion by polyvinyl chloride diaphragm gave results means of on electric arc, has been developed. equal to those obtained with asbestos cloth.4 This process has the decided advantage of Although reports are somewhat conflicting, eliminating the use of platinum. The products, polyvinyl fibers appear to be inferior to asbestos which are available under various trade names, in asbestos-cement products. Silicone rubber i have thermal stabilities in the order of 2,300 F. They have been successfully employed where has been used successfully as a wire covering in certain applications. extremely liigk temperatures are encountered and where giass fibers arc unsatisfactory, as in jet aircraft. Possible substitution of these new fibers for asbestos in cable coverings and elec tronics is being explored. Uses extensive Chemioftl Engineering. Oramir Tiber R#st*T 2J00* VnL 29. S'*.C1*h.eSmvipcairlmler l$$2. p. 1!*I.njutuin? Pa|*rs vs. Aslicstos: VuL h*. No. JulT 1922. p. ?v 4 Blakely, J. D.. l>3ir*y>. Z. L~ Gsr. R_ and lUinierwnj. M. B- BIO.* Kina| Report 4A4 pB 3*rj2. 7 Knumtcii. W.. 1. G. KurWntmiuilw A.-0,, Ludm-ic.Culm. TR FIAT. Trcnnlal and Scientific IWchipmemi Kciaicd U the -\J- 23029. 19*4. po. 170-1*1. ` Lu`hm*-irth. 1. G. FarUmniujim A.-G., LuU*iS3fu*<*ft. THU- tmtot Industry la Germany: Fiml Report lulu, 1MT. 70310. FIAT RW~. B-31 4*k4-i. 3C3S' - SUBSTITUTES 7CR AMC SITE As indicated elsewhere, an important use fo.inosite is for the manufacture of fight, fluffy insulation for use on marine turbines and jet pianos. The fiuffiness appears to be a function fiber diameter; the finer fibers show the lii-rlicr degree of thermal efficiency per unit .wight. Accordingly, it has been found that iili.fr glass haring diameters of less titan ,moron has a thermal efficiency comparable with that of amosite. However, an ordinary lime-soda glass has too low a thermal efficiency for the specialized insulation uses of amosite. Aluminum silicate fibers mentioned in a pre vious paragraph have melting points as high as 2.300 F., which is much higher than tne n-iuperature at which amosite disintegrates. Sm-h fibers, now being made in submicron si/.vs, are said to be satisfactory substitutes for amosite, but their cost is 5 or 6 times as great. Some progress has been made in substituting liber glass for amosite in making 85-pcrcent magnesia insulation. SUMMARY OF CONCLUSIONS ON SUBSTITUTES Other materials may be substituted for asbestos in some fields of use. Glass fibers are ^factory thermal insulators for low-tcmpera. equipment and other applications in which dm fibers are not exposed to water vapor or mitinned flexure. Glass fibers are good electric n-ulators and therefore are used to some ex- 97 . for win? covering and similar applications, "it-"Jos silica fibers will withstand more sev :re weathering conditions and higher tem peratures than the soda-lime-silica glass fibers, ,ut -..-.cir manufacture is difficult. Moreover, their fiexibilky is much inferior to that of asbestos but is improved as processes for making finer size fibers ore developed. Glass fibers are now substituted to some ex tent for long-fiber chrysotile in cable coverings ana fabrics, and more extensive substitution's anticipated. Shortage of platinum might, in an emergency, limit the available supply of fiber glass. The glass fabrics, or the combined glass-asbestos fabrics, have some advantages over asbestos fabrics in lighter weight per square yard and in strength, but they arc generally inferior to asbestos fabrics in resistance to high temperatures, flexure, and chemical action. The processing of combined glass- asbestos fabrics introduces problems affecting the comfort of workers, because glass fibers cause skin irritation. Extremely fine fibers create less Irritation than the coarser ones. Glass fibers in submicron sizes are much more costly than asbestos. With improvement in quality and substantial reduction in cost of manufacture, a wider substitution of fiber glass for asbestos is forecast. hi some applications where the temperatures encountered are low and where chemical re sistance is not important, organic fibers are satisfactory substitutes.* . Data on uf>$muir9 included In thtsdlsrasdon trtrr supplied in pnrt bv i;.v Z. Comeforo, Wctrot<rthaicai Laboratory, Bureau of Minos. Norm. Tena.