Arc lvelding is used extensively in strengthening bridges. The use of the elect'ric arc has saved thousands of st'ructures which otherwise n-ould have required replacement. Corroded and cracked bridge parts have been replaced, and additional strength, necessitated by increased loads, ha> been provided by welding in new reinforcing members. Floor beams are strengthened by welding on cover plates arid well stiffener plates. Stringer flanges are strengthened by n-elcling in plate stiffeners. Corroded column footings, girder or truss bearings, piers or abutments, etc., are repaired by arc welding. The ability of the electric arc t o fuse new metal to old has made it possible to continue in service many bridges which otherwise would have required replacement. N a n y schools and other buildings in earthquake areas have been strengthened by arc Tvelding. Twenty-nine California schools, eighteen in the San Francisco Bay region and eleven in the southern part of the state, have been strengthened. The high tensile strength provided by shielded arc welding more than met specified requireLLientsfor this work. Actual evidence of the increased earthquake resistance provided t,o buildings by arc welding is furnished b y the Los Angeles Building of the Southern California Edisoii Company which has passed through several quakes without being damaged. This thirteen-story structure was completed in 1931 and was provided with arc welded earthquake bracing.
Arc-Welded Frames for Private Dwellings Among a number of steel frame houses erected recently b y arc welding, a twelve-room residence built a t Toledo during the past suninier bespeaks the future possibilities of arc welded steel in dwelling construction. The use of arc welding in erecting the frameivork reduced the cost of steel construction
to a par with wood, whereas former jobs of steel construction have figured at 8 to 19 per cent inore than wood. Thus the arc welding provides t'he home owner with all the advantages of a steel frame dn-elling-fireproof construction and greater no niore than he would pay for ~ ~ o o d . perinanence-for In building the Toledo residence, every possible advantage was taken of arc welding. It was used to reduce the nuinlier of pieces to he handled during erection by asseiiibling the entire wall framework in forty-five panels. These panels were delivered t o the building site ready for erection. Erecting the franien-ork was simplicity itself. The only equipment used was an A-frame and an arc welding machine. I n place of the usual "rat-tat-tat" of the riveting hammers, the only noise which could be heard-and this was only within a few feet of the work-was a steady hiss of the electric arc.
Future of Arc Welding Arc welding, because of the reduced erection costs which it makes possible, will become more widely used as work in the building industry is resumed. The many advantages of the process nil1 be appreciated by architect, contractor, arid owner. Especially in the field of residence Construction will arc n-elding be used to great advantage. The designer \vi11 be eiiahled to produce on his drafting table a drawing for any type of architecture with complete assurance that the contractor can secure any desired result with arc welding. I n turn, the contractor, working with the electric arc, will profit in reduced time and labor costs through use of this fast-workiiig erection tool. And last, but far from least, the owner of the residence will have-for the price of woocl-all the aclvantages of a steel framed home. RECEITEDApril 27, 1935.
Synthetic Plastics J
CH.IRLES A . R R E S l i I ~ 1Iodern . Plastics. New 1 o r k . S . Y.
Qualities Requisite for a Building Jlaterial ELIEVISC; that the proceFh of adapting a new inaterial is gradual rather than revoThe following qualities are requihite for a tiuildiiig nialutionary, t'he plasbics industry ha-. placed terial, and the pla*tic>,a i a group, po.\e+ the-e in unusually empllasis on laboratory derelopment, practical tebtillg, experimental installations. a result of thi. procedure, large nleacure: plastics of certain types are today wide . used by architect-, (1) CGXP.LR.YI.IIELT LO\T. COST. In a study recently made by engineers, and builderb as true and tandard material>-one ~ , ~ i itl d ~ ~found that lanlinated plastics, of the type better for their purpose than any others. In m o d indanceknon-n coninionly as Formica or Micarta, were almost cheap enough, even with today's comparatively limited production, the thought is never elltertail1ed that liere is soniething re1-of o replace plaster, lathe, and paint for interior walls and ceilbUC], lutionary. Plastics in their more colllllloIl ings. Again, the wide and growing number of instances in which a i electrical fixtures, door knobs, wall surface;, store fronts: fronts, store and lobby such laminations have heen for etc., are accepted as a coninion part of the inaterials ai-ailahle interiors, table top,, willsl doors, and toilet stalls, bears testimony to the already existing comfor the builders' selection. petitive p o s i t i o n of the lamiYet ~vithinthe plastic family ntited plastics, particularly when lie possibilities for the archiThe properties of the various g r o u p of thev replace m a r b l e , metal, or tect,,engineer, and builder which svnthetic ticj are o L ~tlined and their highly decorated plaster. are only today being opened u p ( 2 ) L.\RGE A S D C O X S T A S T laminated form i j suggejted for paneling SOURCE OF R.~IIL~ATERI~LS. -possibilities fully as r e v o l u tiollary as any nlentioned for and ciecorative work. \Iolrle[i uses for Here ~ a i the n ~ n t h e t i opl'stic* offer a d v a n t a g e s . T h e y a r e other, shall we say, "mythical" electrical fittings and huilding accessorie? part and parcel of America's great m a t e r i a l s . T h a t the Po--iare oLitlilledt arid phen,,,lics for lighting chemical i n d u i . t r y . The materials from which they are made bilitieJ are to fulfilhllellt fixtures a n d general decorative appliances have shonn a n e x t r e m e l y low i n due in large part t o the con1 comparison of properties factor O f price fluctuation O v e r a are discussea. servative research attitude of long period of years. The plastic* with those of other materials and examples industry can meet any rensonahle the plastics i n d u s t r y a n d ill large part, to the inherent qualiof actual installations which have proved ~ ~ > ~ ~ ~ ~ danget' ~ ~ ~ ? ties of synthetic pla.tic< theintheir worth are included. (3) STRUCTVR.AL QCALITIE~. selves. Here t h e p l l l s t i c s n1u.t h e
OCTOBER. 1935
IUDUSTRIAL A S D EUGISEEHING CHE\IISTRY
recognized primarily as surfaces rather than as weight- or stressbearing materials. Within this limitation they offer, in one or more of their types, high resistance to wear, to weathering, t o fire, to alcohols and acids, to staining and scratching. Certain plastics, particularly the cast phenolics, have unusual qualities for the passage and reflection of light. Others possess unusual shock resistance. Still other.;. heing well suited to withstand quick changes from heat t o cold, are admirably fitted for exterior use.;. In their combinations with metal, asbestos, and other buch materials, they offer an otheriyise unattainable surface while
111.1
the job. The cast plastics must, in their nature, be prefabricated in the factory and merely installed on the job. Yet here again time will call for a wide range of standard shapes arid sizes similar to the moldings available in wood or the shapes available in extruded metals. The molded plistics, vihich today are largely restricted to use as accessories of building (lighting fixture:,Y electrical fixtures, kick plates, door knobs, etc.) are prefabricated. It is likely that a number of molded or tile shapes and sizes will eventually be developed which can be worked up, by units, t o achieve widely varied effects. Thus plastics make their claiiiis upon the architect and builder upon no specious grounds hut rather on t,he very sound basis of their suitability as a building n i a t ~ r i a land particularly ai; a decorative illaterial.
Applications of Plastics ;Imong the molded plastics are a number of applications s o common that few think of theni a.; “plastic” novelties any
WORKABILITY. Here the plastics approach the ideals of the sponsors of prefabrication. Being factory-made, they may he prefabricated in large measure. The laminated sheets may be had in a wide range of sizes, holes may he punched or drilled in advance, or, as is more likely, it minimum of equipment will suffice to permit of working standard sheets into desired shapes‘on (5)
longer. Heat resistance makes them ideal for radiator knobs. Electrical resistance, color, and 4 o c k resistance make them ideal for electrical fixtures, s ~ ~ i t c h eradios, s, plugs, insulators, etc. Resistance t o nyear ha? brought tlieiri into growing favor as ewutcheon plates, bell pus1ie.s and frames:, door knobs, furniture, and door handle;, etc. .Ilthough :t number of stock
INDUSTRIAL AND ENGIIVEEKISG CHEMISTRY
1142
parts are available, they may 81.0 find wide use in building projects where the number of their points of use will ju3tify the cost of a mold. Thus, a hotel, hospital, or large apartment development might economically have its own distinctire molded knobs fabricated to order economically. The laminat'ed plastics, most widely used of all the group in the building field, have found their principal applications t,o date in instances where the alternative materials were comparatively expensive. Thus, scarcely a large city can boast of less than one theater with a laminated plastic lobby, Hundreds of doors and many wall surfaces were made of laminated plastics in the Philadelphia Savings Society Building, Store fronts, running into the many hundreds, have been spread the length of the land. I n Chicago, a large group of outmoded theat'ers were remodeled with laminated plastics as the principal material used, and this is true of many other cities. SVit>hthe advent of repeal, hundreds of bars, grillrooms, and night-clubs have called upon laminated plastics for interior decorative surfaces as \vel1 as for table and bar surfaces. Notable among these are the Casino Club of Chicago, the Vendome Hotel of Buffalo, the Park Plaza Hotel of St. Louis, the Brevoort Hotel of Chicago, the Carlton Hotel of Washington, and the Plaza and Sherry-Netherlands Hotels of Piew York. Transluscent urea-formaldehyde laminations were used in the Chicago fair for signs and for a number of mural decorations as well as in the Deshler-SVallick Hotel of Columbus, Ohio. A more recent development has been the application of
VOL. 27, 50.10
cast phenolics to interior decoration and outdoor signs. This material, familiar to the general public in the form of Catalin costume jeivelry and as clock cases and other small accessories, has been used in a very ambitious manner in decorating the French Casino, a New York theater converted to night club purpojes. Two large bars, numerous lighting fixtures, and a large marquis sign have here been imtalled. The transluscence of the material has been taken advantage of for indirect lighting by means of hidden neon tubes. In the elevators of Radio City, another cast phenolic material, RIarblette, has been used for large ceiling lights, the light weight and freedom from brittleness was a major factor in the choice over glass in this instance. An installation is now in the process of fabrication for the Italian Building in Radio City consisting of four immense plaques illustrative of the Italian Line's coat of arms. Here, color and light reflection mere major factors. Another large installation will shortly be made in a New Jersey theater, where the entire front of the building will be constructed of cast plastics. Thus, plastics have passed beyond the laboratory stage. Definite characterist'ics of all these materials-their workability, their appearance, their wearing qualities, etc., have been proved by actual installations. It is now up to the architect, the engineer, and the builder to multiply the number of applications, and to do this he has a broad background of experience to serve as a guide. RECEIVED April 27, 1935.
(Previous symposium gapers appeared in August and September issue*, and others ~ 1 be1 printed i n November issue.)
Preparation of Iron and Steel for Painting
V. RI. DARSEY Parker Rust-Proof Company, Detroit, SIich.
QP
RESEST-DAY demands for increased
corrosion-resistant finishes on iron and steel products have resulted in more durable organic coatings and improved scientific methods for preparing iron and steel for painting. In general, the useful life of any paint finish depends on two major factors-the durability of the organic coating film it-elf and the adherence of the film to the surface to which it is applied.' Providing metal with a nonmetallic coating of the proper texture adapted to inhibiting corrosion and increasing the adhesion to the final organic finish are the primary factors in the preparation of iron and steel for painting. Permanent adhesion iq clearly the primary requisite for improving practice in painting metal. The cleaning of metal for painting is so common and familiar that it is a p t to receive but minor consideration with regard to the paint coating itself, and the fact that it has a definite function in relation to the useful life of the paint finish is often overlooked b y the manufacturer. The importance of proper preparation of ferrous surfaces before painting has been more fully appreciated in the past two years than ever before, because of the increasing use of cold-rolled or cold-reduced steel and the use of synthetic organic finishes. The tremendous pressures used by the pres1
Hunt, J. K , and Lansing, K, D , IND ENG CREW.,27, 26-9 (1935)
ent-day methods of cold reduction produce steel impregnated with grease and oil to a n extent that makes their removal by old methods of metal cleaning very difficult. To obtain the maximum protection from the synthetic organic finishes, they should be applied over comparatively greasefree surfaces. It is not within the scope of this paper t o present in detail all methods used in the preparation of iron and steel for painting. The methods most widely used are classified into three groups as follows : I. Methods vhich do not change the surface of the metal. 11. Methods which change the surface of the metal either by mechanical or chemical processes. 111. Methods which transform a ferrous surface to a non-
metallic coating.
Alkali and Solvent Cleaning Group I includes various methods of alkali and solvent cleaning which constitute the simplest and most economical methods used in the preparation of metal for painting. These methods provide only for the removal of foreign matter, grease, and oil without imparting any surface change to the
