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Introduction:-

Grades Available
General Properties And Precautions
Dimensional Stability
Melting Vinamold
Mould Making
Open Mould
One Part Mould
Two Part Mould (Split Mould)
Correction Of Vinamold Mould Faults
Preparation Of Masters
Examples Of Applications
Health and Safety Notes
Handling
Melting
Overheating
Fire
Contact Of Hot Vinamolds With The Skin


Introduction

Vinamold hot melt compounds are meltable vinyl compositions used for the preparation of flexible moulds as alternatives to silicone, polyurethanes, and rubber latex rubbers, for casting concrete, gypsum, polyester resins and fibreglass laminates. Because vinamolds are essentially craft materials, few tools and only simply equipment are required. Once the behaviour of vinamold is understood, skill in producing even complicated moulds is rapidly acquired. In use vinamold is melted by heating, poured over the article to be copied, then allowed to cool.


Grades Available

For identification purposes vinamold is supplied in 3 different colours which represent 3 different hardnesses. Yellow is the hardest, red the softest and most fexible, and white intermediate. Where there is a possibility of pigment migration into a light coloured article from red vinamold, the same grade is available unpigmented. Differences between the 3 vinamold types can be summarised as:


Yellow

Melting temperature 150-170ºC (302-338ºC). Pouring temperature 140-150ºC (284-302ºC)

Use where extremely thin sections are involved which could droop under their own weight or where large moulds are required which should not deform under their own weight.

The greater hardness of yellow vinamold minimises deflection and creep.


White

Melting temperature 170ºC (338ºC). Pouring temperature 170 ºC (338ºC)

Use: Combining flexibility with toughness, for moulds to be used in making concrete articles. Has best resistance to damage through rough treatment. For polyester resin casting, white vinamold is preferred to the other types on account of its better resistance to heat rise (exotherm) during setting (cure) and reduced attack by the fire retardant additives present in some polyester resins.


Red (and Natural)

Melting temperature 150-170ºC (302-338ºC). Pouring temperature 140-150ºC (284-302ºC)

Use: General purpose type, and for fibreglass reinforcement laminates.



General Properties And Precautions (See Safety Notes)

Volume/weight relationship. For calculation purposes the specific gravity of all 3 vinamold grades may be taken as 1.0, so that 1 kg equals 1 litre, or 1 Ib equals 27.5 cu. Ins.

Re-use. Unlike some other flexible mould materials vinamolds are thermoplastic, that is to say they melt on heating and re-melt on re-heating. Worn or obsolete moulds may therefore be cleaned and re-used many times over, an obvious economic advantage.


Dimensional Stability

Water. Vinamold materials are not affected by water nor by high humidity.

Temperature. Maximum ambient temperature 80 ºC (176ºC).

Storage Life. Unused materials indefinite. Moulds - many months, subject to careful handling.

Mould Surface Fidelity. Exceptionally fine detail is possible.

Mould Surface Durability. Depends on careful handling and fineness of surface detail.<br>

The number of times a mould can be used may be as many as 100.

Resistance to solvents. Fine surface detail will be damaged by exposure to organic solvents especially acetone, MEK, tetrahydrofuran, benzene, xylene and toluene. Many adhesives, paints, and paint removers use such solvents.

Resistance to detergents. For cleaning dusty mould surfaces detergents should be well diluted. Strong detergents may extract some of the mould release agents incorporated in the vinamold.

Mould lubrication. Generally the lubricants incorporated in vinamold are sufficient. Additional suitable lubricants, if used should first be tested to ensure that no surface damage is likely to occur.

Miscibility of Vinamold Grades. All grades are miscible in any proportions to arrive at intermediate flexibilities.

Physical Form. 25 kg slabs.

Melting Vinamold

The more care and control exercised in melting vinamold the more times the material can be re-used. Thermostatically controlled melting equipment is preferred.

Alternative simple melters can be constructed in the form of air or sand baths, utilizing vessels (for example cans) one inside the other with a gap all round of at least 12.5mm. It is recommended to restrict the volume of melted vinamold in these simple devices to 5 kg (11 Ibs.).

Under no circumstances should oil be used in place of sand or air- hot oil can cause serious burns and can easily ignite.

Whether thermostatic or simple melters are used the practice for melting is the same - cut the material into small pieces, melt a small quantity, then add further pieces, melt these, add more pieces and so on.

Excessive fumes during melting indicate overheating which will be followed by discolouration of the vinamold, and eventual decomposition to a charred and unusable state.


Mould Making

There are essentially 3 types of mould for which vinamold can be used:

A. Open moulds for flat articles.

B. One part moulds for simple nonflat articles.

C. Two part moulds for complex articles incorporating register system. Apply release agent to fibreglass edge.


For ease in understanding the mould making descriptions, the various terms are defined:

Master. The original article which it is desired to copy.

Replica. A copy of the master. Several replicas may be used to simultaneously make a number of vinamold moulds for quantity production.

Casting. The final article taken out of the vinamold mould, made from concrete, gypsum, etc.

Wall. Raised part of an open mould which decides the final area and depth of the mould.

Case. A container for the vinamold mould, designed to give support to prevent distortion during the eventual casting process.

Cone Funnel. Device for pouring melted vinamold steadily into the mould cavity. Typical proportions for a cone funnel - top opening diameter 1 unit, bottom exit diameter 0.5 unit, height 3-6 units.

Riser. It is necessary to be sure that the mould cavity has completely filled, the most positive means being a visual check. For this purpose a riser is incorporated in the mould system to allow melted vinamold to fill the mould then rise to a level as high as, or slightly higher than the top of the mould cavity. The riser may be a simple hole in the top of the case but is preferably a second cone funnel placed opposite the one used for filling. Melted vinamold fills the first cone funnel, then the mould, then rises up the second funnel. Pouring is stopped when the vinamold can be seen to have risen high enough.

Air Vents. Holes which allow air to escape from the highest points in the mould cavity, so ensuring vinamold fills mould cavity 100%. Air vent diameter minimum 3mm (1/8 in.).

Mould Cavity. The space between the master or replica, and the wall (or case). Equivalent to the vinamold mould mass.

Register. The two halves of a split mould must fit together perfectly to prevent the final article exhibiting the effects of misalignment. When the halves match 100% they are said to be registered. A means of assuring this is by the use of pins, pegs or other register devices on one part of the mould case, which locate into matching holes or depressions in the other part of the mould case.

Guides. Pins or pegs in one part which fit into corresponding pockets, rings, sleeves, or holes in the second part to ensure register of a two part mould.


A. Open Mould

For the production of gypsum ceiling tiles, concrete paving slabs, concrete commemorative plaques and decorative features (e.g. Bank emblem's) in bas-relief or high relief.

Step 1. Fix master or replica on a flat board

Step 2. Using clay, wood or other suitable medium make a wall all round 25mm (1 in.) Higher than the highest point of the master/replica. Depending on the proportions of the master/ replica leave a space of from 25mm (1 in.) To 1 50mm (6 in.) All round between the wall and master.

Step 3. Pour melted vinamold slowly and steadily over the master/replica until level with the top of the containing wall.

Step 4. Leave 8 hours to cool.

Step 5. Lift the vinamold mould carefully off the master and turn over.


Note: For convenience in handling make a box round the vinamold mould.

The mould is now ready for use.


B. One Part Mould

For the production of concrete building components,bollards,simple animal/human figures in gypsum; pre-production samples in polyester resin etc.

Step 1. Secure master/replica on a base board.

Step 2. Cover master/replica in clay to a thickness of about 20mm (3/4 in.). The clay represents the thickness of the final vinamold mould i.e. The mould cavity.

Step 3. Using gypsum reinforced with hessian, or fibreglass, build up a case of a suitable thickness relative to the size of the master/replica (up to 25mm/1 in.) Incorporating a fixing flange (see Step 4) and allow to set. Mark position of case on base board.

Step 4. Remove case and extract all the clay. Return case to pre-marked position on base board and fix down with screws, bolts etc., through fixing flange.

Step 5. Remove case from base board and prepare case with 2 (minimum) cone funnels by making holes 25-50mm diameter as near base board level as practicable. Cone funnel holes should be opposite each other, or equi-spaced if more than 2. Height of the funnels must be such that filling and riser funnels will level at about 150mm (6 in.) Above the highest point of the mould cavity. The cone funnels should, of course, be tight fits in the entry/riser holes in the case to prevent leakage of molten vinamold during filling. Depending of complexity the cavity should be provided with air vents, one at the uppermost point at each part of the cavity.

Step 6. Pour vinamold slowly and steadily to prevent air bubbles entering and causing porosity in the mould. Air should dissipate back through the filling cone funnel. When vinamold is seen to be flowing out of the air vents these should be plugged to prevent unnecessary spillage. Stop pouring when vinamold fills all funnels.

Step 7. Allow to cool for 8 hours.

Step 8. Pull out cone funnels, cut off vinamold at entry/riser holes. Remove case, mould, and master/ replica, leave vinamold in case.

The mould is ready to use.


C. Two Part Mould (Split Mould)

For the production of statuettes, busts, complex technical articles.

Step A. Select natural plane(s) (vertical, horizontal, diagonal or combination) along which to split the mould.

Step B. Follow Steps 1-7 as for one part mould, to make first part as far as selected split line.

Step C. Plan register and guide pin system, then support first part in a convenient position. Repeat procedure to Step 3 as-for one part mould,

Step D. Again follow Steps, 4, 5, 6, 7 described for one part mould. After removing clay (Step 4 - one part mould) treat first vinamold surface with release agent - talc or shellac.

Step E. Separate mould parts, remove master/replica.

Step F. With reference to the master/replica, select and make a hole at the most appropriate (concealed) position through which to fill the mould with gypsum, concrete etc., and the best attitude (angle) for mould filling.

Step G. Fill mould, allow to set and check for air entrapment. Provide air vents as indicated.


Correction Of Vinamold Mould Faults

Small faults, due to air bubbles, tears, or deficiencies in the master, can be corrected by carefully touching up with a hot blade. Small pieces of vinamold can be fused into the mould surface to take up cavities.


Preparation Of Masters

N.B. If a master is rare, valuable, or delicate take extra care in sealing and pre-warming. If in doubt as to the possible effect of sealing materials or heat please consult us. We will advise you to the best of our ability, but we can accept no responsibility for damage to masters howsoever caused.

Porous Dry Clay or Gypsum. Seal surface with G4 sealer.

Wood. Experiment with surface sealer. Epoxy resin may be used as a sealer to prevent bubble formation in vinamold due to air and moisture from the wood.

Concrete or Stone. Fill pores by soaking with water. Allow surface to dry superficially prior to pouring vinamold.

Metal. No sealing is necessary. A thin film of mineral or vegetable oil will facilitate removal from the vinamold.

Porcelain and glass. Carefully prewarm to prevent breakage when vinamold is poured over the masters.

Clay. (Modelling or Natural). No preparation needed.

Fibreglass. Pre-heat for 30-60 minutes at 300ºC to ensure full cure and freedom from volatiles.


Examples Of Applications For Vinamold

Construction Industry

Prefabricated concrete panels, decorative panels, coats-of-arms, company emblem's.

Interior Decoration.

Ceiling and wall embellishments pateras, cornices, friezes. Period decorative effects - furniture, mirror surrounds.

False beams; wood, stone, and brick simulation panels. Doors, plaques, armorial crests. Especially effective in bronze and aluminium filled polyester resins.Suspended ceiling, acoustic and thermal insulating tiles.

Used in homes, bars, restaurants, hotels, banks, ships saloons, civic buildings, colleges, etc.

Tourist Souvenirs

Replicas of antique items, figurines, doll heads, masks, historical replicas.

Educational/Museums/Arts and Crafts.

Three dimensional topographical maps, biology models, sculpture replicas, fossil casts.

Some more unusual applications of vinamold are in life-size human figures, utilising the flesh-like consistency of the material; isostatic pressure transfer (acting as a solid hydraulic medium).


Health and Safety Notes

Users of vinamold must read the Safety Data Sheets. Before handling or using the products.

Vinamold grades are formulated with non-toxic materials to meet the Safety Requirements for Childrens Toys in British Standard BS 5665: Part 3 (1989) and European Standard EN 71: Part 3 (1988).


Handling

Vinamolds are generally quite harmless to handle, provided certain simple precautions are taken. Used and unused materials must not, for instance, be allowed to come into contact with food and food utensils. Measures should be taken to see that vinamold does not come into contact with the skin, since people with sensitive skin may be affected. The use of barrier creams or gloves is advised, and the skin should be thoroughly cleansed with soap and water at the end of the working period.


Melting

During the melting stage, avoid breathing fumes at all times. The fumes associated with the melting of vinamold are caused by the volatility of the plasticising compounds used in the material. None of the plasticising compounds are considered toxic, so the vapours produced during the heating of vinamold are a nuisance rather than a hazard. Nevertheless, for the comfort of the user, and to avoid any possible irritation of the respiratory tract, we would always recommend adequate ventilation and extraction as necessary in the area where vinamold is being heated, to remove fumes.


Overheating

If melted at the correct temperature in a ventilated room, it should hardly be possible to smell vinamold. However, serious overheating will lead to fumes and decomposition, and if prolonged can cause respiratory irritation, whereby possible damage to health cannot be excluded.

In order to avoid overheating, check the melting compound by using a thermometer graduated to 200ºC; if using an electric melting pot, adjust the thermostat if necessary, after checking the melting compound with a thermometer from time to time (e.g. Weekly). Overheating is indicated when the material fumes heavily and changes colour to dark brown or black; in which case remove from the heat and the working area. Discard burnt material. New vinamold should not be mixed with burned or very old vinamold.


Fire

Due precautions must be taken against possible fire risk. Keep vinamold away from flames and electric elements, particularly when vinamolds are in their molten state.

If vinamold catches fire, dry sand should be used. Drenching with water is best avoided, since it turns to steam and may be hazardous in confined areas.


Contact Of Hot Vinamolds With The Skin

Melted vinamold (150ºC+) can cause more serious burns than boiling water (100ºC). If skin comes into contact with hot vinamold, the affected area should be held under cold running water for two minutes followed by an application of an anti-burn ointment; subsequently a loose dry dressing should be applied in order to exclude air. In case of severe burns, medical attention should be sought as soon as possible.


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