BUILDING AND HOMES

Dominion, Volume 24, Issue 64, 9 December 1930, Page 16

BUILDING AND HOMES

(by

JACK PLANE)

COLOURING CONCRETE Recent Developments VARIOUS EXPERIMENTS lu America, where elaborate moulding and modelling of concrete was first taken up on a large scale and is now carried on extensively, much attention is being paid to the colourin'g o£ this popular constructional material. It has occupied the thoughts of members of the American Concrete Institute, whose chairman, Mr. Raymond Wilson, has dealt-comprehen-sively with the subject. His views, and those of others in that country, as well as recent experiments here, are deserving of consideration. Roughly, the colouring of concrete can be obtained by three methods: By (1) integral admixture of finely-divided inert pigments; (2) the use of coloured aggregates (coarse or fine or both); (3) surface treatment by (a) penetration or staining, (b) painting. Success in 1 and 3 depends almost entirely on the chemical nature and physical condition of the pigments. Mixing Pigments.

As regards 1, the pigment must be finely divided iu order to secure uniformity of tiuting, and should be thoroughly mixed iu a dry state with the cement. .If added to the mortar or concrete during gauging patchiness or streaky effects are almost inevitable. Dr. Maximilian Toeh points out that any pigment with a specific gravity higher than that of cement is apt to sink, causing stratification. No doubt this effect, if controlled, could be utilised, obtaining graduated coloration, cloudy at the top, deuse nt the base. But the result on the physical condition of the concrete would have to be taken into consideration. As a rule, heavy pigments should be ground very fine, and the mix in which they are used should not be too wet. As regards the chemical nature of the pigments, they must either be inert or at any rate not interfere with the cement to its detriment, and they must be stable us to staining qualities, both under exposure to atmosphere' and the action of cement. Mr. Wilson recommends iron oxides for producing reds, yellows, browns, and blacks; manganese dioxide for green, ultramarine for blue, carbon pigments for black. With these a good range of colours can be obtained, though without brilliance. Except in • the case of carbon, a 10 per cent, by weight addition to the cement gives satisfactory results, though he holds a much higher percentage can be adopted without detriment to the strength of the concrete. Iu this, as we shall presently see, he differs from the British Portland Cement Association. He excludes the use of Prussian blue, cadmium lithapone, zine..and lead chromates, nnd considers organic pigments unstable. Dark Concretes. As regards black, while carbon gives a good colour if used in sufficient quantity, it is found difficult to incorporate uniformly when in excess of 3 per cent, by weight of the cement, and in that case also tends to reduce the strength of the concrete. For these reasons he prefers black oxide; this, however, is expensive. But, as he explains, expensive pigments, when purchased by. weight, are often the most economical, having higher staining powers, and therefore going farther. He advocates the use of grey cements for dark-coloured concretes, and white cements when the colours are to be light. Dr. Toeh excludes all pigments containing soluble salts and all those which combine with free lime as it is generated; so he considers all copper salts and lead salts as dangerous. Any colouring containing calcium sulphate reduces the strength of concrete and produces efflorescence. Efflorescence. Efflorescence is one of the destructive agents as regards coloration, and to minimise the danger to stability the cement used should not be hot and should be well aerated, while the concrete mix should nof be too wet. Dr. Toeh considers cadmium colours safe if used in limited quantities. They are valuable on account of their brilliance and permanency. He considers para, chlor para, and toluidine reds safe pigments in the organic group. Recent experiments by the British Portland Cement Association go to show that red oxide increases the strength of ordinary rather more than.that of rapidhardening cements. Compressive strength is also improved by ultramarine blue, yellow ochre, chromium green, oxide anil manganese black, and there is increased teusile strength in rapid-hardening cemeut with the use of blue and green pigments. These experiments proved that as a rule a 10 per cent, addition gave better results than either a 5 or 15 per eent. admixture. Carbon black was found to distinctly lower the strength of concrete. (S) Colouring by Means of Aggregates. This method is of considerable artistic merit, admitting of many modifications. Colour combinations can be obtained by the choice of the larger aggregates .or the sand, or bath. By hand packing of largish smooth - faced aggregates, the amount of the cementing matrix can be reduced to the minimum, with the attainment of the maximum amount of coloration and the reduction of any tendency to efflorescence. More commonly, exposure of the coloured aggregate ifi obtained by scrubbing of the surface with a wire brush and plenty of water after the initial setting; or by washing with an acid" solution and rinsing with pure water at a later stage. Uniformity of coloration or conglomerate (plum-pud-ing) effects may be aimed at. (3) Surface Treatment: (a) Penetration. This is usually applied to hard trowelled floors, but also occasionally for wall linings and . dadoes. Coloration is obtained by chemical reaction between . a constituent of the colouring matter and a constituent of the concrete (either cement or sand) with the formation of coloured products in the surface pores. Thus ferric oxide sales produce a; precipitation of hydrous ferric oxide, resulting in a reddish brown pigmentation. Not only browns, but reds, greens, and greys can. be obtained in this way. Usually a fluosilicate hardener is mixed with the pigment. The stain is appliet several times, ■ being allowed to dry between each application. An oil wax treatment is adopted for the finishing process. (b) Surface Painting. Painting' on new concrete should be delayed as long as possible. The surface should be dry and receive a preliminary neutralising wash of a zinc sulphate solution. This is commonly followed by a priming or filling coat of linseed oil, then a priming coat of paint-well thinned in linseed oil. Each coat must be allowed to dry thoroughly. Dr. Toeh considers fluosilicate of zine far better than sulphate of zine as a neutraliser. He is against the use of raw linseed oil as a filler on concrete or cement mortar, because the fatty acid and the lime forms soluble salts which are apt to soften the concrete and destroy the stability of the subsequent coats of paint. I-ie prefers China wood oil with copal resins. This is not harmful, while it gives a flint-like surface for the finish. Linseed Oil. This question of the use of linseed oil as a filler or a paint medium still presents many difficulties. Investigations by the Building Ilesearth Station at Garton, near Wattord, show that failure of linseed oil paint applied to insufficiently dried out concrete or cement , rendered surfaces is not caused by the caustic effect of lime alone. Failure is only found when free lime and soluble salts of soda and potash are present. Experiments are also being carried out by paint-manufacturers, with , the result that various types, of ready-mixed paints for eement apd concrete surfaces are to be found on the market. Reliable as many of these are, even they have to be used with care under differing characters of cements and natures of mixes —G. Cadogan Rothery. in “The Illustrated Carpenter aud Builder.”

STRAY NOTES Colour in Factories Some interesting observations on ths use of colour in the interior finishing of modern factories and workshops arc made by a writer in a British technical journal. It is now generally recognised, he says, that eye comfort, aud its influence on mind, has much to do with bodily health and the physical and mental ability to do good work. Pure white, while useful as reflecting light, is often too staring, causing eye strain by excessive glare quite as effectually as dull colours with deficiency of light will do. Dull colours are also depressing. The specific influence of colours ou health may be debatable, but it is amply proved that soft, cheerful colours in decoration are beneficial. The managing director of an important concern says: “A year or two ago, after readiug some books ou the therapeutic value of colours in room decoration, we decided to have the walls of our tiu box factory coloured a soft primrose yellow. The effect is very pleasing, and the colour more restful to the eye than the usual white. We have had no means of testing it, but we are satisfied that the strain ,to the eye of the worker is much less than it would be under the ordinary conditions of white walls. In any case we shall certainly not return to the white. Confirmation of tin's is provided by the opinion of a medical member of the Welfare Society, who held a quiet yellow or orange to be a good colour to adopt for workshop decorative schemes. . . The fact is, too much stress cannot be laid on the need for eye comfort. Eye strain is not merely a localised discomfort; it influences mind and body, and therefore quality, if not quantity, of output. To translate this ipto practical politics it comes to this—the factory and work" shop must be made as comfortable and cheerful as possible, though necessarily without extravagance. In this paint can be of the greatest help. In many cases there are other excellent wall linings, such as glazed (tinted) tiles, in which decorative dadoes and friezes, even of quite simple kind, can be quite effective. In others polished wood (in which plywood can play its part) is indicated, or with modern methods of. construction arid internal fittings, glazing with one or other of the appropriate sheet glasses which are being produced in such astonishing variety .by British manufacturers. ■ In the long run, however, it is paint that is of the most universal application. For interior use it is far better than lime white or cement washes. Washable distempers are often good, though .when of'reliable quality and when renewals are taken into consideration, they are not so economical as oil paints, which resist harder wear rind atmospheric conditions if the ground has been properly prepared. As regards tints, light yellows and creams are to be preferred, with orange for decorative details, as these reflect light without glare; are cheerful, without being stimulating, like reds. Pale, creamy greens are useful where a softened light is required. Bluljs are to be hyoided, and must not be prominent in the make-up of greys or browns. Large expanses should be broken up, if only by means of dadoes or friezes, and if only by a slight.difference in the shade of colour.

Another Important point is the finish ing coat. There is much temptation to adopt a highly glossy finish, as this looks bright and cheerful, reflects light, is not easily soiled, and quickly washed down. Under certain conditions, in factories and workshops with deficient natural lighting, a glossy finish is admirable. But in other cases, especially where delicate work has to be carried on under artificial lighting, a glossy finish has distinct drawbacks, causing glare and perhaps awkward deflection of illuminating rays. Then a matt finish must be chosen. As a rule a semi-matt finish is to be preferred. If the tint is light it will reflect without glare. Whether the finish be glossy or ihatt, the surface should be as smooth as possible, so as to minimise the collection of dust and make washing down an easy and quick process. Where wood linings and fittings prevail, varnishing is necessary. The wood should be light toned, not heavily stained, and the varnish nearly colourless. Here, again, a matt, or semi-matt, varnish is to be preferred for our present purpose to a highly glossy one. PLEASANT LAUNDRY The hoine-i'eformers have beautified the bathroom and made the kitchen a place of comfort and joy. Now what about the laundry.? Is your laundry a pleasant place to work in or is it a steamy, stuffy eyesore? When showing visitors round, do you say in front of the shut door, “Oh that's the wash-house,” or do you throw open the door and exclaim, “And here’s my laundry!” In many neat and artistic homes the laundry is merely the dumping ground for anything in the way of old clothes, boots, tools iwid tins of paint. But it need not be. Washing at any time is not the most pleasant task, but in unpleasant, inconvenient surroundings It is a wearisome job. Why should all Hie rest of the house be treated artistically and the laundry ignored? An energetic housewife recently moved into a house in which the laundry had, as usual, ugly, untouched red brick walls, a gas copper, two cement troughs (the wood-work of which had never been painted, and was very grimy), and a piece of worn nondescript linoleum on the floor. The newcomer rolled up her sleeves. First of all thd walls bad to be white-washed over. This was not such an arduous task, for the room was like most laundries, quite small. Next the wood-work around the troughs and window was thoroughly cleaned with plenty of soap and water, and then given two coats of flat paint and two of lacquer in a lovely soft shade of blue. Lacquer dries rapidly and gives a very high gloss and hard finish. The troughs and copper were also lacquered this saine shade of blue, on the outside, while the handle of the copper lid and the taps, which were very tarnished, were painted a very deep iv.ory. At the windows dainty curtains of hail-spot muslin were hung, and across one corner of the room a long curtain 1 of gay cretonne, in which the same brilliant bine predominated, was placed. Behind this, garden tools and boots, an old coat, etc., were placed handy, yet quite hidden from sight. The result was most pleasing, nnd when a light coloured linoleum of tile design was laid the room looked most attractive. Surely washing iu a laundry such ns that would be much mere interesting than in the usual type! To brighten up vour laundry always choose a cool colour. The steam from the clothes makes the room fairly hot always, and any of the gayer tones, such as tango and red. make the room look hot and stuffy. Black and white makes a practical colour scheme, but of course in that case all the paint-work would probably be white nnd just picked out in black. The black and white could be carried out in tiled linoleum and cheek curtains. Reseda green is also a very attractive shade. Your paint-work would be of the green, the picking out in silvafros, linoleum cream with a touch of green, and the curtains either green crepe or Indian head, or, if something a little gayer is fancied, a cretonne of bold design in green and mauve tonings. Lemon and black, too, make a good colour scheme. So there is no need to be ashamed of your laundry. A-tin or two of paint, and ii short length of cheap curtain material, a medium amount of energy, and you can have a laundry that your are not only proud of, but glad to work in.- E. J. D. Corr, in the “Australian Home Beauti- < ful.” ■

COOL ROOMS Many houses in hot weather, says a writer in the “Ideal Home,” convey an impression of stuffiness, of startling furniture and carpets, and of almost tangible heat coming in from outside. The secret of a really cool house lies in shutting the hot air out instead of letting it in, and in suiting the furnishings to the season. Most people, even though they lower the stinblinds, keep their windows wide open all day, admitting the sun-seorched air, and then they wonder in the evening why the rooms feel hot and airless when all‘is cool outside. All windows should be kept wide open until the sun comes round to that particular side of the house. Then shut every one and lower the sun-blinds over them. 1 , , There is real common-sense at the bottom of this rule, for the cool early mornin" air is thus imprisoned inside the house, and the hot noonday air kept out. The next thing is to prevent a stagnant atmosphere. Open doors create a certain amount of draught, and an electric fan will help. , A fan is not such a luxury as it sounds, for. it is rarely necessary to keep it running for any length of time. A quarter of an hour or twenty minutes in each room should be enough to keep the air fresh.. Nothing looks cooler on a hot nay than highly polished floors and sparsely placed furniture. Therefore roll up all heavy carpets during a heat wave, and put away any unnecessary chairs or tables. Window furnishings are important. Soft nets that sway in the breeze are the ideal summer curtains, so are the brighter toned cretonnes and linens. It is useful to know that pattern and colour play an even more important part than texture in achieving a cool effect. If the long inner curtains are of a suitable design and colour it is rarely necessary to take them down. There are several types of satisfactory sunblinds, but the best colour to choose in every case is green. Green is very restful to the eyes, while red and pure white cast a very trying glare. If you choose a striped linen blind, green and cream is the ideal combination. Any mention' of hot weather calls to mind the evils which come in its train—notably flies and other insect pests. The American method of combating these pests is by means of wire screens made to fit the open windows, an excellent way, but one not generally known over here. , __ Light wooden frames, covered either with mosauito netting or with the very fine-meshed wire gauze which is used for the doors and sides of meat safes, would be simple to make. Fine net, tightly stretched on wooden rods at the top and bottom of the window, would serve the same purpose. 1 ... , Spike oil (oil of lavender) is refreshing and a preventative for flies. Soak _a small piece of sponge with it and hang it up near the centre of the room. Eau de Cologne burnt in a saucer also refreshes the air and perfumes the room pleasantly. ■ One of the greatest aids to coolness is the miniature electric fountain. Most of these are entirely self-contained, so that there is no need for any elaborate tubing dr connecting to the water supply, and they will play continuously at the touch of a switch. They are entirely charming on the dinner table, in the lounge or the hall. Some of them also hold flowers, and any more lovely combination than flowers and running water can hardly be imagined. Coloured lamps can also "be placed inside the central frosted glass cone with a very pretty effect. There is something in the sparkling quality of glass which conduces to coolness, and we should use .it as much for ornament and on the dinner table as possible. I , u Flowers, by the way, should be used with a lavish hand, together with ferns and,other plants, not sparsely in small vase's, but massed in such places as the empty fireplace and the table centre.

SUMMARY OF TENDERS CLOSING DURING THF PERIOD DECEMBER 9 TO DECEMBER 23. Public Works office. —Tenders, alteration and additions St. Helen’s Hospital. Close 4 p.m., December 9. Atkins and Mitchell, Wellington.—Tenders erection building corner Cuba and Vivian Streets. Close noon, December 10. yy.C.C/—Tenders erection building, Lambton Quay, shop and offices. Close 9.30 a.m., December 11. Edmund Anseombe, F.N.Z.1.A., 8 The Terrace, Wellington.—Tenders .erection residence, Seatoun. Close 2.30 p.m., December 10. Petone Beautifying Society.—Tenders miniature golf course. Close noon, December 11, Swan, Lawren<?e, and Swan, 81 The Terrace, Wellington.—Tenders new hotel, Petone. Close 4 p.m., December 17. Swan, Lawrence, and Swan, 81 The Terrace, Wellington.—Tenders liall and building, Taranaki Street, for Wellington Qity Mission. Close noon, December 18.