Gelflex is a meltable PVC Resin, which can be poured over a model to form a flexible mould. Good tensile strength and flexibility will allow castings with deep undercuts to be removed from a one piece Gelflex mould without damage. The material melts at 120º - 135º C and is poured over suitable masters. A release agent is not normally required. A major advantage is that when the mould is old or worn and requires replacement it can be cut up, remelted and reused.
HEATING APPLIANCES
Up to about 1 kg can be carefully melted in a metal saucepan on an electric hotplate or a gas ring. Larger quantities, up to 5kg can be melted in aluminium Maslin Pan with a flat base, the tapered pan being supported by a cylinder of sheet aluminium under the handle brackets so that its base is 10 mm above the surface of the hot plate. This arrangement requires a thermostat in the heating circuit. In all cases lids should be fitted and a thermometer used to prevent overheating and kept under constant attention. The equipment must stand on a fireproof bench or floor. Neither of the above methods is advised for permanent usage, as they can be hazardous in unfavourable circumstances. An oil bath must not be used and water of course cannot be used as its temperature does not rise above 11º C. Small quantities of Gelflex can be melted in a microwave oven by placing the diced material in a microwave proof dish and covering with Clingfilm and heat for about 4 minutes on a high setting.
MELTING INSTRUCTIONS
Cut the Gelflex into small cubes, about 25 mm (1") or smaller, and melt about half the quantity required stirring gently with a wooden spoon or spatula to achieve an even temperature. When it has melted add the remaining Gelflex and stir occasionally. If overheating occurs, the material will fume heavily and rapidly change to a dark brown colour, in which case remove from the heat source and avoid breathing the fumes by taking it outside if possible.
MOULD MAKING
A model of almost any rigid material can be used provided that it will withstand the melting point of the compound. Porous materials such as plaster of Paris, wood, cement, etc. should be sealed to prevent entrapped air from escaping and forming bubbles on the mould face. This can be done by applying two coats of a solvent based lacquer especially designed for use with Gelflex. We understand that 'Unibond' also makes a good sealer. Metal or nonporous models do not require sealing before pouring Gelflex. Models should be fixed to a level baseboard.
For large moulds some form of support will be necessary. For example, a sheet of aluminium rolled into a cylindrical shape and placed around the model. This should be tied to prevent unrolling. Before pouring place damp modelling clay or similar material tightly around the outer base of the cylinder to prevent leakage. In cold conditions, large bulky metal models should be warmed to prevent rapid setting of Gelflex. Pour the molten Gelflex slowly down the sides of the mould box to prevent air bubbles and splashes. Take care not to pour the liquid directly onto the model. Continue to pour until the mould is covered to a depth of at least 25 mm (1") above its highest point. Allow Gelflex to cool and set before removing the mould from its support.
Most models can be eased gently from the mould by hand. If the model has undercuts that prevent the mould from coming away freely then the mould will have to be cut. Where possible cut the back of the mould and use a number of elastic bands to hold the mould in position. The cut edges will not interfere with the castings. The mould is now ready for use without the use of release agents. Small blemishes in the mould such as blisters may be repaired by gently playing a small flame, such as a gas jet over the defect until it melts to a smooth surface. A heated knife blade is also useful to even out rough spots, bubbles and makes good repairs.
REMELTING
When the mould becomes worn, it can be cut up; any dirt can be washed off with water and household liquid detergent without affecting the compound after cleaning the material is ready for remelting. The melting appliance should be clean and free from charred material. Burnt or very old Gelflex should not be reused.
HEALTH AND SAFETY INFORMATION
Gelflex is made from polymerised PVC resin, and is considered quite safe to handle provided that sensible precautions are observed. When melting there will be some fuming which originates from the plasticisers which are unpleasant rather than harmful. Adequate ventilation is therefore very important.
Prolonged skin contact should be avoided and people with particularly sensitive skins should use barrier cream.
Ingestion should be avoided and food and drink should not be allowed in areas where Gelflex is stored or used. Smoking should also be avoided. Th the event of ingestion, medical advice should be sought.
Molten Gelflex is considerably hotter than boiling water and will stick to the skin. Handle with care using suitable gloves and eye protection.
In the event of a skin burn, place the affected part under cold running water for at least two minutes or apply an anti-burn spray or ointment and cover with a loose bandage or dressing. In cases of serious burns seek medical advice.
If molten Gelflex is to be carried any distance then suitable containers should be used with well fitting lids.
Gelflex is solvent free with a flash point of approximately 3200F. It will not ignite rapidly but a persistent fire could cause ignition and decomposition which is acidic and toxic in nature. In the event of fire, use dry sand or CO2.
ADDITIONAL INFORMATION
The recommendations and technical information given in this leaflet are based on our research and general experience. Whilst we believe this information to be accurate and reliable, no guarantee of it's accuracy is made and it is understood that you will, by your own tests, determine the suitability of this product for your own particular purpose.
Reproduced by kind permission of TRYLON LTD
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