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Master Moulds

Boiled Sugar Master Moulds
Ice Cream Master Moulds
Chocolate Master Moulds
Bronze Toy Mould

            The earliest ICE CREAM MOULDS were of sheet metal, cut and soldered into geometric shapes and required no master moulds.[Please see the collection at Peabody Essex Museum in Salem, Mass. Image] Later they were poured in various alloys of tin and lead, copper, antimony, (only English has the term “Pewter” for the group). BOILED SUGAR MOULDS in tin eg. pewter or seltzer [tin+ zinc] or sometimes cast iron were also poured into master moulds and so are considered here. The shipping weight for the sulfur master mould was 18.5 kg.
            Master moulds’ matrix could be metal, stone, plaster, sulphur or even wood. Customarily 19th and 20th century craftsmen used copper, brass, bronze ( best sharpness of detail and the surface was retained indefinitely) and cast iron( less crisp and more fragile). They were collimated with cusps and sockets or pins and holes. They were kept together with wooden handles, hand held pincers or a vise. Scores of pewter moulds could be cast from a single master mould in a single day.
            For pewter ice cream moulds a design would be drawn and a sculpter would produce a positive model in clay. This would be shiped to the bronze foundery where it would be put in a mould box and carefully and tightly surrounded by moist, very fine, sand for an impression of each half of the model. The model would be carefully withdrawn and the sand cast placed in a drying oven for two to four days so that all the water would be dried off. Even a few drops of water touched by the super hot molten bronze to be poured in would turn to steam and explode shattering the sand mould.
            When the sand mould was dry liquid bronze would be poured into the cavity. When the bronze had cooled it would be removed from the sand mould and returned to the maker. There an expert, usually the sculpter, would 'CHASE' the mould to remove burrs and other tiny defects accumulated douring casting. At this time the tiny hairline channels from the peaks of the mould cavity to the surface for the escape of air as the mould filled with peweter would be added to the surface of the bronze.
            Two halves of a master mould had to be made for each part of a pewter mould, except when the parts were identical, and then both parts could be poured from the same master mould. (The finger tabs in the finished pewter mould would then be exactly opposite rather than separated as is usual.)
            The inner, male half, of the master mould is called the “drag” or “core” and carries in relief the design to appear on the inside of the pewter mould.. The outside, female half of the master mould is called the “Cope” and carries the "Marks" to be seen on the outside of the pewter mould and slots for Hinge and Finger lugs.
            The aperture by which pewter is poured into the master mould is called the “Gate”. When the mould is being filled with pewter some is left in the gate. It is called the "tedge" and serves as a reservoir; as the pewter cools it shrinks and the edge fills this gap in the pewter mould. The remaining tedge, called the "Sprue" is filed off after the mould is opened. Fine channels from the high points of the cavity to the outside vent the air being displaced by the pewter.
            During World War II bronze was confiscated for the war and bronze master moulds were replaced by cast iron. In the drag portion bronze inserts were retained for particularly detailed places such as faces. [ Please see the collection of the master moulds of the Skandinav ick Konditor- Forretning of Copenhagen at the Stockholm Museum]
            In 1914 the USA government began requiring imports from foreign countries to be labeled “Made in Germany” etc. Georg Lieb of Stuttgart, responded by making subsidiary master moulds for the American trade with a drag of sulphur and cope of plaster, adding the phrase “Made in Germany” to the latter.

            CHOCOLATE moulds were stamped in sheet metal. They too require two forms in the master mould for each part of the final mould. They are more appropriately referred to as “dies”. Deep moulds required three or four stampings beginning with simple shapes and progressing to more intricate pattern designs.(When a detail did not fill out, placing a pellet of solder under the spot and recompressing the mould would usually fill it out.). Large show pieces were hand hammered into shape over wooden forms.
            Iron rusts and copper in an acid environment corrodes to toxic "Verdigris". These problem were overcome by dipping the iron or copper into liquid tin. Later the coating of a supporting metal with a protective softer, safer or smoother metal was accomplished by annealing: sheets of the 2 or 3 metals, in 1x0.5 meter “Plates” , hence “Plating”. The plates were heated very hot and rolled between heated rollers under tons of pressure in an atmosphere of nitrogen (free of oxygen to prevent rusting). Less than 3 or 4 plates a year became unstuck. Electro- plating, the depositing of a layer of a second metal on the first by electrolysis from an anode, was invented in 1805. By mid century it was being used as a simpler, cheaper more thorough method of plating.
            Stainless steel was invented in the 1870s and perfected in 1914. Now-a-days, chocolate moulds are often pressure molded in plastic which are much cheaper. However they are usually copies of metal moulds and so are less crisply detailed. Only a few can long survive use at higher temperatures such as molding boiled sugar.

Boiled Sugar Master Moulds

#37420 GL
Santa Clause Mould

Ice Cream Master Moulds

 

Chocolate Master Moulds

A. Two Part Master Mould

B. Three Part Master Mould

An 'L' shaped 3-pin alignment plate is inserted in the holes and left for the run of the mould production. Sometimes the plate becomes crumpled and is discarded or as here is lost and the nikel/aluminum sheet for the mould is placed by the operator by hand in the outline square. D-Ring = Deflection Ring.
The D-Ring is floating on the neck of the male mould supported by pins in holes of the base plate which press against the sides of the D-Ring, supporting it.

 

Stamping Process

	Female Die pressing down on nikel steel sheet on top of Male die and d-ring.
	Finished mould laying in female die.
	Side view of the body of the male die sliding through the opening of the deflecting disk or 'd-ring'.

Developing 35 tons of force used at the American Chocolate Mould Company from the 1940's-now. (Courtesy of Frank Friedwald.)

 

Bronze Toy Mould

Not a bronze master mould for pewter candy moulds because it has only two sides instead of four and because it has spikes for attachment to a wooden carriage.

 

The making of a master mould:

1) An artist makes a drawing of a possible subject for a mould of a boiled sugar candy or an ice cream.

2) A sculptor makes a clay model (first positive model) to the correct dimensions of the final boiled sugar or chocolate candy or ice cream.

3) A designer makes a plaster model to the specifications desired (negative).

4) A second plaster mould is made (positive).

5) A sand cast is made (negative).

6) The the bronze master mould is poured then chased and burnished to remove imperfections (positive).

7) Pewter (negative).

8) Boiled sugar, chocolate, ice cream (positive).

Sometimes an object is used in place of a clay model like the example below.