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Manufacturing of decorative products from plaster (ch. 2)

Casting of products from a plaster solution . The structure of a plastering on manufacturing and installation of decorative products from a plaster solution includes following operations: preparation of models, manufacturing of forms, casting of products in forms, installation of finished articles. However at use of relief tiles the quantity of operations can be reduced because instead of model manufacturing in the form stack a ready relief matrix from rubber, plastic, etc.

The Model is the future product executed from any material on drawing, the drawing or a photo. From model subsequently receive the form for casting of products.

It is possible to do Model of plaster, clay, plasticine, a tree etc. For manufacturing of models of decorative relief plates or tiles it is possible to use plaster. A necessary relief ornament cut out according to the technology described in section "рхчіср on ушяёѕ". The received plaster model cover with shellac.

Sometimes model make of the separate elements cut out from plaster and pasted on in advance cast plaster plate. For this purpose on a plaster plate draw necessary drawing, and then a plaster solution paste the cut out details. Then carefully close up all cracks and roughnesses, a surface smooth out a small soft skin, and after drying varnish. Models of rectilinear draughts, i.e. pogonazhnyh products of a various configuration, carry out from plaster by means of a template. As a template basic element the profile board which has been cut off at an angle 90° serves; which do from prjamoslojnoj, not knotty ostrogannoj wood. On a board in the mirror image cut out necessary contours of draught. Drawing transfer on a board, putting to it the drawing represented on a paper and pinning its any edge on a contour or directly drawing drawing on a board. The transferred drawing cut out on a contour with skosom so that one side of a board had a corner 30-40°.

A very often profile board for protection from fast istiranija about a solution cover tonkolistovoj with the zinced steel. For this purpose from it cut out precisely same profile and beat it on a wall of a template with an acute angle then carefully process a file.

Then start manufacturing of other elements of a template: a sled, polozka and podkosov. A sled serves for installation on them of a profile board. polozok it is beaten to the bottom party of a sled and serves for an exact direction of a sled on directing rejke. podkosy, in turn, are intended for fixation of a profile board in the set position (fig. 59). All details of a template should be stroganymi that the stuck plaster solution was easier cleaned off.

For performance (vytjagivanija) rectilinear draught a template establish on a wooden board, on one of which end faces it is fixed directing, acting over a board plane on some centimetres. That on a board it was convenient to work, it stack on a table or a workbench which surface in this case can be made from simple nestroganyh boards, ground smetanoobraznym a solution which there and then level a rule. After full hardening of a solution a ground process tsiklej, receiving thus a smooth equal surface with which then cover shellachnym with a varnish.

The Template establish on a board so that polozok concerned directing rejki. It is necessary to watch that the thickness of model on all section of a product did not exceed 3-4 see In those places where it more than this size, do linings for formation of emptiness in plaster draught. Linings can be from clay or from a tree covered with clay. That plaster lagged behind a lining is easier, clay cover with a paper.

The Model should not do more long 100 sm as such draughts are jarred on and lose straightforwardness.

Templates for vytjagivanija models of draughts (pogonazhnyh elements): and - rectilinear; - curvilinear; 1 - directing rejka; 2 - polozok; 3 - laths ' 4 - a template; 5 - a ground; 6 - stapnaja okovka; 7 - radiusnaja rejka; 8-tsentrovoj a pin; 9 - a portable support; 10 - draught

a Fig. 59. Templates for vytjagivanija models of draughts (pogonazhnyh elements) :
And - rectilinear; - curvilinear; 1 - directing rejka; 2 - polozok; 3 - laths; 4 - a template; 5 - a ground; 6 - stapnaja okovka; 7 - radiusnaja rejka; 8 - tsentrovoj a pin; 9 - a portable support; 10 - draught

Before the work beginning directing rejku, polozok and a template for the best sliding it is recommended to cover with greasing, for example vaseline. After that in gipsovke plant a plaster solution, maintain less than 1 mines to weak zagustenija and impose a shovel in that place where the template will move. On the laid solution slowly move a template not cut off party forward, removing a solution and making out thus a draught profile according to a template contour. Thus its surface remains rough. At movement by the cut off party forward the profile board smoothes down a solution. Therefore vytjagivanie draughts also it is divided into two stages: at first not cut off party with an acute angle clean off a solution, and then the cut off party it smooth down. At repeated nabrasyvanii a solution it is necessary to fill the bowls formed on a surface. It is necessary to mean that in the course of work a template all time shift only in one party, i.e. For following movement it transfer to a starting position. Vytjagivanie not cut off party continue until absolutely smooth profile of draught without bowls and roughnesses is formed. After the received draught will harden, a template stretch on a model surface once again, cutting off the top layer. It is necessary for doing in connection with feature of plaster at hardening strongly to extend and get jammed a template that complicates the further work on model. Before starting removal of the top layer of model, it is necessary to humidify a surface with water well.

After that model moisten with liquid plaster and some times stretch a template the cut off party forward, achieving thus accurate, direct and pure lines. The ends of the received model cut off at right angle and accurately smooth out a small emery paper.

Models of curvilinear elements extend also by means of a template which strengthen on rejke, nasazhennoj on tsentrovoj a pin, thanks to it the template circles. Make a template so. In the beginning cut out a necessary profile of draught in a profile board and fetter tonkolistovoj the zinced steel. By the end of a profile board removed from the centre of draught, beat a lath in length of 10-20 sm which serves as a sled. The ends of a sled mow down like runners for sliding reception on a ground. By other end of a profile board beat rejku with an aperture on the end. The length rejki steals up so that the general distance from a sled to an aperture in rejke equaled to radius of necessary curvilinear draught. For performance of the round socket, for example, having smooth increase in a relief to the centre, do a corresponding template in which provide places for an ornament moulding. Make model in such sequence.

On the grounded board appoint the centre and into it drive in a nail, on which nasazhivajut rejku a template with an aperture. Rotating a template round an axis, define a place for nabrasyvanija a solution. Thus level on which a sled is fixed, causes a thickness of the future socket. Then throw a solution and rotate a template round an axis, extending, thus, a circle. If under a sled the solution gets, it should be cleaned off, as the stuck solution will increase a thickness of the socket.

All elements of an ornament of the socket mould from clay. If the ornament symmetric mould one of repeating elements of an ornament in 1 / 8 , 1 / 6 or 1 / 4 a part of the socket which then cast in plaster and is finished by details. Of the received casting do the elastic form and cast necessary quantity of segments of an ornament which paste on the socket basis a plaster solution.

Models make of clay also on the special wooden boards which end faces on all perimetre are upholstered wooden rejkoj, acting on 15-20 mm. It is necessary to cover a board surface with a clay ground. For this purpose all area of a board moisten with water, then rub with a piece of soft clay and after that on all surface of a board stack clay. Surpluses and roughnesses of the laid clay remove equal ostrogannoj wooden rejkoj or a rule, spending them on a framework board. If there are bowls, they are filled with clay and again level rejkoj. This operation is necessary for spending until the ground surface does not become equal and smooth.

Clay for a moulding of models is necessary for soaking and well to mix. For this purpose it stack in capacity layers on 15-20 sm and fill in with water for days. Clay should razmoknut to testoobraznogo conditions. Then it spread on a wooden board and carefully mix. In the course of hashing it is recommended to strike on clay a metal core or an edge wooden rejki. Well prepared clay should be kneaded easily by fingers, without sticking to hands. That clay did not dry up at storage, it necessarily cover with the rag moistened in water, is better a sacking. Model from clay mould on the grounded board under sketches, drawings or a photo. In the course of a moulding use the minimum tooling including stacks, loops, kijanku and compasses. In work on model in the beginning make the plate basis, then on it mark drawing and mould basic elements of ornaments, passing from large forms to details.

At work on models of small products instead of clay often apply plasticine. It is convenient that it can be used repeatedly.

Models can be made also of a tree, cutting or turning on the machine tool separate elements of a relief and pasting or filling them on a board with in advance prepared drawing.

Manufacturing of forms. If a relief of model of a tile simple, and all vertical walls of elements of a relief have the biases allowing freely to take off the rigid uniform such form prepare from a plaster solution directly from models from various materials. For preparation tselnej a plaster mould the model covered with a varnish, put on a marble slab or thick glass, and around on a plaster solution strengthen a framework from wooden reek, the plywood, the cut strips of glass and other materials. If the contour is curvilinear, the framework can be made of roofing iron (tonkolistovoj the zinced steel). Before pouring of a plaster solution model and a framework cover with greasing. Fill in model smetanoobraznym with a plaster solution. After drying the form remove about models and an internal surface varnish.

If the model from clay or plasticine has a difficult relief, in the beginning do the draught form, and then plaster casting.

Manufacturing techniques of the draught form from model, for example, sockets, such. In the beginning prepare a plaster solution on the water tinted by colour pigments. The solution should have a consistence of liquid sour cream. A layer in the thickness of 2-3 mm cover with the received solution the model laid on glass or a marble slab. After the solution has seized, over it put more dense solution a layer of 20-50 mm. After hardening of plaster the form overturn and it is cautious not to damage relief fine details, delete from the form model. This work is better to carry out wooden stacks or scrapers, and also water under a small pressure. The insignificant rests and clay or plasticine traces delete a ball from this a material, prokatyvaja it under the form.

The form Cleared thus should be dried and to varnish inside. Before the beginning of casting of plaster model on an internal surface put stearin greasing. The prepared form fill in with a plaster solution, and after shvatyvanija a solution overturn and stack on a desktop for clearing of the made casting of the form.

Release it in the following sequence. In the beginning the top layer of the form cut down a chisel until from under usual plaster the colour layer will not seem. It means that before the casting remains 2-3 mm, therefore the further work it is necessary to spend with the maximum care not to damage casting. By means of various tools all details of model can be worked more carefully that will raise quality of an ornament.

Modifed model dry and varnish, then it is ready to manufacturing of the fair form. Forms of products with a deep and difficult relief is better to make of glutinous structure or formoplasta. For reception of glutinous structure technical gelatin at first presoak in water on 10-20 mines, then dry for the purpose of removal of a moisture within an hour and cook in klejanke 1,5 hours. For increase of elasticity and durability of the future form in weight add glycerine (500 g glycerine on 1 kg of dry gelatin) and that the form did not rot, it is possible to add 3-5 g phenol.

Glutinous weight from mezdrovogo glue prepare similarly, only presoak glue in water within days. Make the glutinous form as follows. The prepared model stack on thick glass or a plate, and round it on distance of 20-30 mm suit a framework from glass, wooden reek and other materials and fix it from an outer side a plaster solution. The framework height should exceed height of the uppermost point of model not less than on 10 mm. After that on model, the basis and a framework from the inside put stearin greasing or vaseline. Through 15-20 mines surpluses of greasing delete. Glutinous weight cool to temperature 35-45°Р, and then fill in with it the space formed by a framework, on all height. When the glutinous weight completely will fall asleep, delete a framework and take off the uniform from model.

That the form did not collapse from a moisture, it tan the cooled solution aljumokalievyh alum for what in 1 l of water of a room temperature dissolve 120 g dry alum. Instead of alum sometimes use 30-40%-s' solution of formalin. Having strewed a surface talc, forms wash out a solution. Talc is necessary for the best vpityvanija a solution. This operation repeat after drying of the form during 1 ch.

That the form was not deformed, it should be placed in a plaster case. For this purpose the form stack again on model, make on corners of deepening for fixing, grease and cover with a plaster solution a layer of 20-30 mm. If the form of the big sizes, a plaster case it is necessary to reinforce thin rejkami or a wire. From the inside a case varnish.

Forms from formoplasta with which help it is possible to make products with a relief of various height and biases of elements of an ornament are especially elastic.

Formoplast make industrially. Rasplavljajut formoplast in thick-walled capacities from aluminium alloys on an oil bath or in a basin with the sand put on fire. The fusion temperature should not exceed 130°Р that formoplast has not lost the properties. Fill in formoplast after it will settle during 10-15 mines while the weight does not leave air vials.

If the model is executed from clay, of it do the form without any preparation. From plaster it is necessary to impregnate model with hot natural drying oil with addition of 5-10% of rosin to reduce porosity of plaster which influences quality of the form. A film formed on model in the course of drawing of drying oil, it is necessary to remove a brush moistened in turpentine.

The model Laid on the smooth basis protect a framework from wooden reek, glass or a roofing tin which fix a plaster solution or clay. The formed space fill in fused formoplastom at temperature 125-128°Р. Direct weight at nalive on the highest point of a relief that promotes uniform distribution formoplasta on all model.

Forms from glutinous weight and formoplasta can be removed from any models executed from firm materials: from plaster (a carving method on plaster), wood, metal and other similar materials. Thus it is necessary to consider that at manufacturing of the form from formoplasta the temperature of a softening of a material of model should be above 130-140°Р.