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INDUSTRIAL AND ENGINEERING CHEMISTRY
July, 1923
M A T E R I A L S OF C H E M I C A L - E Q U I P M E N T CONSTRUCTION SYMPOSIUM ~~
Papers presented before t h e Division of Industrial and Engineering Chemistry at t h e 65th Meeting of t h e American Chemical Society, New Haven, Conn., April 2 t o 7, 1923. T h e other papers in thts symposium were published tn t h e M a y a n d June issues.
The Protection of Concrete and Other Building Materials against Water and Noxious Fumes By Maximilian Toch TOCH BROTHERS, INC., N E W Y O R K , N Y .
TEEL, concrete, wood, and brick arc the principal building materials used in factories; but in residences, office buildings, and warehouses, stone, plaster, and oxychloride compositions are also used.
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CONCRETE
If surface area is taken into consideration, probably concrete is inore largely used than all the others combined. It is well to quote from an editorial opinion of the Engineeri n g News-Record of February, 1923, owing to the many doubts as to theory and practice which were brought out a t a recent meeting of the American Concrete Institute: First, there is a very general concern over the behavior of outdoor concrete. More and more, bad concrete is being brought t o light, and the policy of suppression of facts is retreating before a demand t h a t the cards be thrown on the table. There are all too many examples of five t o fifteen-year-old concrete, placed by competent contractors and engineers, which are far from permanent and which if examined and classified might reasonably yield some information t h a t would help in future structures. When failures have as much publicity as tests, the reasons for the principles laid down will be better appreciated. In the same category comes t h e well-worn subject of seawater concrete. For years this has been the plaything of the theoretician. Concrete goes to pieces in sea water more frequently than not, but the fact t h a t sometimes it does not points t o need of a study comprehensive in scope and particularized in examination. In concrete construction several questions are not definitely answered. One is t h e matter of integral waterproofing, and another the desirability of chuting. It is common to decry integral waterproofing, to claim on the basis of many tests t h a t nothing is added by the use of such materials t h a t cannot be just as cheaply and effectively achieved by the proper procedure of normal concreting-and yet, integral waterproofing continues t o be made and used in large quantities. I n chuting, on the other hand, theorizing has no place. The unsuccessful attempt at Cincinnati t o get some registration of opinion one way or the other on the chute problem shows why there are doubts on this question. Skepticism as to rational methods of proportioning is far less than it once was; there are signs t h a t we are approaching some sort of solution. The problem now is to popularize methods which need simplifying and broad asting. Doubts here are nowhere near as great as they were fivi years ago.
The first fact, with regard to untreated concrete, which strikes us most forcibly, is that u p to 1914 the United States Kavy did not have a single great dry dock in good condition, but, particularly, the Brooklyn navy dry docks had t o be continually patched and repaired where they had cracked abnormally, or where the sea had leached them badly. Some authentic photographs are recorded in the article on concrete in Baskerville’s “Municipal Chemistry.” The five gigantic dry docks built b y the Kavy in Norfolk, Philadelphia, and Xew York, since 1912, have all been waterproofed by the integral method, and sufficient time has
passed, particularly in the case of the S o . 4 Dry Dock of the Brooklyn Navy Yard, which is over nine years old, to indicate that no deterioration or solution of mortar or concrete has taken place. Sidewalks made of concrete do not receive any treatment, either by the integral os surface method, and as a rule they show up very well. This is probably due to the fact that sanding, dusting, and abrasion of the sidewalk is not noticeable. I n this climate, where the tempernture variation approaches 130 degrees or more, concrete roads crack badly, as a rule, and must be filled up with a bituminous or elastic material. Before they are repaired frost usually enters and then the fissures widen. Some engineers maintain that concrete needs no integral or surface treatment whatever, if additional portland cement is added and if the workmanship is proper, but this is only partly true. I n the first place, it is a question whether exact supervision can be had in large construction work, and, of much greater importance, there is the problem of chuting. Chuting saves time and labor, but sometimes, in very large operations, 20 tons of concrete are loaded on a car propelled anywhere from 100 to 1000 ft., and the contents are lifted into a chute and allowed to slide into place. Unless an integral material, mhichacts as a lubricator and which slightly retards, is used, bad concrete is going to result and clogging may take place; but when no proper integral material is used, the slidpis wet and additional water is added to the concrete so as to make it slide-too much water to concrete is fatal. For example, in a very large government building in Washington, in which the closest supervision was had over the concrete work, the addition of too much water in the concrete of which the floors were made resulted in one of the worst cases of cracking that the writer has ever seenin fact, every floor in that gigantic building is alligatored to a tremendous extent. Engineers ought to look this problem squarely in the face and not theorize about how it might be done without the addition of some protective material. You cannot build a concrete bin or building in which certain chemicals are stored unless the concrete is acidproofed, either integrally or by means of a thorough surface application, and you cannot dust-proof and harden a cement floor, no matter what formula of cement, sand, and aggregate you devise, unless a suitable material is applied to the surface. STEEL The protection of steel i n buildings has been very much neglected since the war. Building construction is so expensive-the plasterer, the mason, and the carpenter are getting infinitely so much more than they did before the war-that the owner is inclined to take it out of the material man, and is willing to use a cheap brick, cheaper paint, and cheaper materials generally, often t o his sorrow; but in a chemical works this cannot be permitted, where steam-laden fumes carry a small percentage of free chlorine or sulfuric acid, which is a common occurrence in many factories. There is no one who can definitely say that one material will act as a panacea for all these conditions, but many of these cases have to be treated individually.
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Free chlorine and the fumes of bleaching powder are so corrosive that a paint that will withstand sulfuric acid will not withstand chlorine products-in fact, in many instances it is advisable, where rust pittings are very bad, t o paint the steel with a waterproof paint and then put on a 1-in. coat of portland cement grout, which of itself must be exceedingly dense, and which should then be followed with an alkaliproof, acid-proof, or chlorine-proof paint, as the case may be. WOOD
Wooden vats present a very important problem in painting. Some years ago i t was the general impression that a wooden vat, whether connected with a sprinkler system on the roof of a building or used in the interior of a building, needed no coating, but looking out over the sky line of the City of New York, where practically every big building is sprinklered, and therefore has a 5000 or 10,000-gal. tank from 10 to 20 ft. above the roof, you seldom see one that has not been painted on the outside, and even if you do see one that is unpainted, the hoops are always painted. There is a simple problem in engineering which regulates why a vat should be unpainted on the inside and painted on the outside-one of tension and compression. From the writer’s experience-and his firm has over 100 wooden tanks in its factory-he has found that continual painting and continual looking after the hoops save the price of many a new tank. I n alcoholic fermentation, when beer was manufactured in this country, it was found that the only material which was suitable for the painting of the interior of wooden fermentation tanks was a mixture of practically pure, acetone-free ethyl alcohol and 4 lbs. of the highest grade of East India shellac, known as “DC” or as “VSO,” and because only between 3 and 5 per cent of alcohol was generated, the coating was not affected and withstood the action of the mash for about six months. It was subsequently found, however, that this mixture, which was known throughout the trade as ‘(brewers’varnish,” was expensive to apply, and a great many objected to it on account of the alcoholic fumes. Since then a much better material has been placed on the market, which is in the form of a wax. It is unaffected by acids, alkalies, or alcohols, and is harmless to the workman who applies it, because it contains no volatile matter. This appears to be a very high grade of resin copal, similar t o kauri, which has been melted with some form of wax, and when this material is applied with a blow torch and thoroughly impregnated into the interior of the tank, it has been known to last for four or five years. Chemical manufacturers have adopted materials of this type for the interior of vats, and experiments show that both strong vinegar and hydrochloric acid have no effect on a coating of this type.
BRICKAND HOLLOW TILE Brick and hollow tile should either be painted or should have a colorless application where the original texture is to be preserved. In the last few years we have made so many advances in the treatment of tung oil that these colorless coatings are to be had in endless varieties. A camera which occupies two rooms of the Department of the Interior building is now used for photographing maps of the United States, maps of oil fields, and charts showing mineral resources. The lens, bellows, and copy-holder are in one room, and the plate-holder and dark room are in the other room. The camera will take a picture one yard square It weighs 7000 lbs. and is operated either by hand or by electricity. Focusing IS done by means of a n electrical contrivance.
Vol. 15, No.?
The Resistivity of Various Materials towards Photographic Solutions’ By J. I. Crabtree and Glenn E. Matthews EASTMAN KODAK Co., ROCHESTER, N. Y.
A
LTHOUGH much information is available in the litera-
ture concerning the effect of alkalies, acids, and numerous other solutions on materials which might be suitable for constructing trays, tanks, film holders, etc., for photographic purposes,1s21*very little of this information throws any light on the probable effect of photographic solutions on these materials. The suitability of a material from a photographic standpoint depends on two factors-namely, the resistivity of the material to the action of the photographic solution, and the effect of the material on the useful life of the solution. The second factor is of great importance, since a solution such as a developer may appear unchanged after a week’s exposure to a metal, but on testing the developer may be found to fog emulsions badly. In. this event the metal would be,entirely unsuitable for constructing developing apparatus, but i t might be satisfactory for fixing, washing, or toning apparatus. A material which is resistant and does not produce undesirable effects with any photographic solution is, of course, t o be preferred. Of the possible materials suitable for constructing photographic apparatus, the following were considered: 1-Metals, plated metals, and alloys 2-Nonmetallic materials: Enameled steel Glass Impregnated fibrous materials Lacquered metal Porcelain and glazed earthenware Rubber, rubber composition, and nitrocellulose materials Slate and alberene stone Wood
METALS,PLATED METALS,AND ALLOYS The ductility of metals and alloys and the fact that they can be readily soldered and welded would seem to render them particularly, suitable for the manufacture of photographic apparatus; although to date no satisfactory metal or alloy is known which is entirely suitable for use with all photographic solutions, it is necessary to restrict their use to specific purposes. Fixing baths are the most corrosive on account of their frequently high acidity, and in a used bath, if any metal less noble than silver is immersed therein, silver is deposited on the metal and an equivalent quantity of the metal goes into solution. Such a coating of silver usually renders the metal more resistant, though if the under layer of metal is exposed to an acid solution free from silver, electrolytic corrosion sets in. Pure silver is satisfactory except for toning solutions. Lead has been extensively used for lining wooden tanks and trays, and has proved satisfactory except for some toning solutions, while lead-coated stee13j4 offers promise. Zinc has been used for washing tanks and is fairly satisfactory for this purpose. Pure tin has long been employed for conveying distilled water. Nickel-plated brass is satisfactory for small developing tanks when they are used intermittently, but plated metals invariably corrode in contact with fixing solutions. Thus, a nickel-plated copper rack for holding photographic plates fell to piece^.^ 1 Communication No. 176 from the Research Laboratory of the Eastman Kodak Company. Numbers in t h e text refer to the bibliography a t the end of the article.
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