Object of the Invention

This invention relates to a compact, light-weight mixing device for mixing water and casting plaster (herein referred to as plaster), for the purpose of preparing a plaster mix for introducing into a casting mould in order to construct decorative plaster units. The device is sealed which keeps the mix from becoming contaminated as well as stopping any plaster from escaping, thereby ensuring health and safety of the user and cleanliness of the workplace.

Background to the Invention A plaster cast is a three-dimensional form made in plaster. Typically, it may be a replication of an original form, for which a mould has been created, thus allowing an exact replication of the original in term of size and structure. The mould itself may also be a plaster cast (in the form of a negative impression of the original form). Potential examples of the original form are a part or a whole form of a sculpture, a building facade, a face, a fossil or a fossilized shape such as a footprint. It will be appreciated that the original form is in no way limited to these examples.

When using plaster to create moulds, it is important to match the plaster to the requirements of the situation and in particular take into consideration the time frame for which the mould will be used. Plaster formulations differ in terms of their porosity, the time it takes for the formulation to set, and the strength and shrinkage of the cured plaster etc.. All of these factors impact the choice of plaster formulation and make some formulations more suitable for certain uses than other formulations.

A basic property of casting plaster is its ‘normal consistency’ or the amount of water required to mix a given amount of plaster to a state of fluidity. Both the plaster and the water are measured by weight and the required amounts are expressed as a numerical ratio. When less water is used and the mix is therefore less fluid, the setting time and the period of plasticity for the mix are comparatively short. When more water is used and the density of the mix is reduced, the setting time is lengthened. The consistency affects not only the setting time but the hardness and the compressive strength of the set plaster as well, which in turn correlates closely with resistance to breakage and durability. The higher the consistency number (ie the more water required), the softer and weaker is the resultant final plaster. The consistency number represents the means by which plaster becomes solid through the formation of tightly interlaced crystals and as more water is added, these crystals are pushed further apart, thus making a weaker structure.

As the water-to-plaster ratio is an important factor in the overall performance of the plaster mix, it is a critical factor for consideration when making plaster casts. When correct or optimum proportions are mixed at an appropriate rate, the plaster gradually reaches a creamy state, becoming more opaque than thin and watery. Such an opaque stage is indicative that the plaster is ready to be poured into a mould. If the plaster does not reach this stage, it is typically an indication that there is a problem with the water-to-plaster ratio.

In light of the above, it is clear that the ratio of water to plaster plays an important role during and after the casting process. Accordingly, it is highly desirable that these two components (water and plaster or water) are mixed in a correct or optimum ratio to facilitate adequate performance of the mix. It will be appreciated that the preferred embodiment is suitable for water and plaster (or adhesive or plaster adhesive) mixes, however, the device is suitable for mixing other particle based material with a fluid and the scope of the device is not limited to water, plaster and adhesive.

The prior art typically involves pouring a certain amount of plaster from a bag of plaster into a container containing water and hand mixing the plaster and water or using a mechanised stirrer to mix the water and plaster. The plaster may additionally be weighed out in advance of pouring it into the water, thus the plaster may be transferred into several containers before being mixed with water. The plaster is in the form of extremely fine particles. T ransferring plaster from one container to another typically results in a large amount of plaster dust circulating in the air in the vicinity of the transfer. Plaster dust represents a considerable safety concern as inhalation of this dust is harmful to the human body. In addition, this fine plaster dust may settle on other objects in the area, causing a host of additional problems in ancillary equipment. As the transfer does not take place in a sealed environment, the risk of contamination of the plaster is also relatively high, particularly if multiple transfers take place. The device of the present invention overcomes aforementioned issues with the prior art as it provides a sealed environment in which specific amount of plaster can be released into a container of water.

The present invention is reusable, results in very little waste and is efficient in consistently obtaining optimal results. The present invention thus represents a significant improvement over the prior art.

In addition, the present device ensures that the inoculation of dust (also known as ingress of dust) into the plaster mix is kept to a minimum in order to prevent undesirable contamination. It also prevents any casting plaster (dust) escaping which is important for the health and safety of the user and overall cleanliness of the workplace.

Summary of the Invention

The present invention provides a compact and light-weight device. The present device allows for the economical use of plaster as there is little wastage associated with mixing a pre-measured amount of casting plaster with a predefined amount of water in a sealed environment in order to achieve a resultant plaster mix which is of suitable consistency and opaqueness, whilst also keeping dust levels and potential for contamination to a minimum.

Preferably, the device is suitable for mixing an optimum amount of casting plaster and adhesive with water thereby resulting in a plaster mix having a required consistency and opaqueness, whilst at the same time keeping dust levels in the plaster mix to a minimum, the said device comprising the following components: Container A comprising a plurality of compartments which can be prefilled with required amounts of casting plaster and adhesive;

Container C comprising a sieve located at its base and a rubber seal located along its periphery; and

Container D comprising markings for pre-filling Container D with required amount of water through using the markings as a water gauge 20 wherein each compartment of Container A includes a sliding door (also referred to as a slider) having horizontal handles for pulling the sliding door such that, in use, a required number of sliding doors are pulled back thus allowing a required amount of plaster and / or adhesive to fall from Container A to Container C, and from Container C through the sieve to Container D thus allowing the required amount of plaster and/or adhesive to be mixed with the required amount of water which has been pre-filled in Container D.

Preferably Containers A, C and D of the device act both as independent detachable units as well as mutually interacting units.

Preferably Container A is empty and may be filled prior to use.

Preferable Container D is empty and may be prefilled prior to use.

Preferably, the size of Container A, C and D must be coordinated such that each of the containers is stackable in a vertical configuration, with Container A being stackable on Container C, and with Container C being stackable on Container D.

Preferably, in use, Containers A, C and D are aligned in a vertical orientation such that the lowermost Container D is pre-filled with required amount of water using a water gauge 20 provided on Container D. Slidably attachable Container C is located on top of Container D, slidably attachable Container A is pre-filled with required amounts of casting plaster and/or adhesive and located on top of Container C whereby Container A is secured over Container C through rubber seal present along the periphery of Container C, thereby preventing inoculation of dust from the outside as well as stopping any casting plaster from escaping.

Preferably, Container A is made up of a recyclable material.

Preferably, the ratio of water to casting plaster used for the purpose of the invention ranges from 1 litre water to 1.30 kg plaster to 1 litre water to 1.55 kg plaster. It will be appreciated that the invention is however not limited to this specific range and other ranges are possible whilst still falling within the inventive concept of the device.

The device according to the invention is an assembly of a plurality of components and broadly comprises three Containers, A, C and D. The containers function as both independent detachable units as well as interacting units which support the overall functioning of the device as a whole to enable the mixing casting plaster and water, i.e., they act both as independent detachable units as well as mutually interacting units.

According to one aspect of the invention, a first container, Container A comprises a plurality of compartments for both casting plaster and/or adhesive required to form a plaster mix. Each compartment comprises at least one orifice and each orifice comprises a corresponding slider which can be pulled out or slid inside the compartment. When the slider is positioned across the orifice it prevents the contents of the compartment from being released thereby holding inside a pre-measured amount of casting plaster and/or adhesive while at the same time preventing any seepage of dust inside the contents of the Container A. When the slider is slid into the open position, the contents of the compartment fall out of the compartment into a vessel below (wherein the vessel below could be another compartment, or the vessel below could be Container C or Container D. It will be appreciated that the contents of the compartment fall due to gravity. The falling motion of the contents of the compartment may be assisted by shaking the device or providing the device on a vibration table or similar device.

Preferably, Container A is made of a recyclable cardboard.

Preferably, the sliders in Container A include horizontal handles at one end so that they can be easily manipulated (opened or closed).

Preferably, Container A includes a handle on its uppermost end in order to facilitate its transportation.

Container C comprises a sieve mesh for sieving and passing required amount of plaster from Container A to Container D.

Preferably, the base of Container C is fitted with a sieve of suitable mesh size.

In an alternative embodiment, the sieve may comprise a series of horizontal bars rather than a mesh. Preferably, the sieve may be removable such that a variety of sieve types and sizes can be used for different plaster applications.

Preferably, Container C is made up of a transparent, cost-effective hard plastic.

Preferably, the periphery of Container C is fitted with a rubber seal or similar sealing material.

Preferably, Container D is provided empty. Prior to use Container D is filled with an optimum amount of water (using a gauge 20 which is provided on a sidewall of Container D) depending upon the consistency and density of the plaster mix to be formed using the device.

Preferably, the capacity of the compartment of Container A and the markings of the gauge 20 of Container D correspond such that, for example, if a user fills Container D with water up to mark 2 and opens 2 compartments in Container A, then the consistency will be the same as filling the water in Container D up to mark 4 and opening 4 compartments in Container A.

Preferably, Container D is made up of a rubber material having a hard plastic top to allow sliding of Container C over Container D.

Preferably, in a rectangular or square embodiment, Container A comprises at least one of the following dimensions: 170mm height, 250mm width and 250mm length.

Preferably, in a rectangular or square embodiment, Container C comprises at least one of the following dimensions: 400mm height, 500mm width and 500mm length.

Preferably, in a rectangular or square embodiment, Container D comprises at least one of the following dimensions: 300mm height, 350mm width and 350mm length.

Preferably, in a cylindrical embodiment, Container A comprises at least one of the following dimensions: 170mm height, 250mm width and 250mm length. Preferably, in a cylindrical embodiment, Container C comprises at least one of the following dimensions: 500mm diameter and 400mm height.

Preferably, in a cylindrical embodiment, Container D comprises at least one of the following dimensions: 350mm diameter and 300mm height.

It will be appreciated that the dimensions of the containers may be smaller or larger than the preferred values.

In use, Container D is filled with an optimum amount of water as required, keeping in mind the consistency and density of the plaster mix to be formed. An appropriate mesh is selected and fitted onto Container C and Container C is slid on top of Container D. An appropriate number of compartments of Container A are filled with plaster and/or adhesive and stacked on top of each other and then Container A is stacked or slid onto Container D. Thus, Containers A, B and C are aligned in a vertical orientation. The rubber seal present around the periphery of Container C holds Container A securely in place and forms a lock/seal preventing any inoculation of dust from outside.

For the purpose of mixing optimum amounts of plaster and/or adhesive with optimum and pre-determined amount of water in Container D, in order to form a plaster mix of required consistency, a suitable number of sliding doors in Container A are pulled back such that the required amount of plaster falls from the respective compartments of Container A into Container C. For example, if water is filled up to the second mark on Container D then two of the sliding doors of two compartments in Container A are opened to give the correct plaster to water ratio. It is possible that some compartments may be filled but not used in the process. It is thus important that the compartment sliders are opened from the bottom up, such that plaster and/or adhesive does not get trapped in a compartment which will not be opened. The amount of plaster not used in Container A can be used in the next mix thereby saving costs and producing less waste of plaster.

Following the pulling of required number of sliding doors of respective compartments in Container A, the required amount of casting plaster falls down from Container A into Container C. Some of this plaster and/or adhesive may fall directly into Container D but any plaster and /or adhesive which has not yet fallen through Container C from Container A is then transferred to Container D by shaking the device such that the amount of plaster and / or adhesive present in Container C passes through the sieve located at its base to enter and mix with the proportionate amount of water already present in Container D. The sieve slows down the amount of plaster and / or adhesive that falls into the water. This ensures that all the plaster and / or adhesive does not fall in at the same time yet falls fast enough that it gives a user time to work with the mix.

Preferably, Container C is shaken until all the plaster and / or adhesive has fallen through the sieve and into the water in Container D. The rubber seals in Container C stops any plaster and or adhesive from being released from the device, therefore, keeping dust to a minimum.

Once the measured amount of plaster and or adhesive has been transferred through the sieve of Container C into Container D, the two containers can be detached from each other.

The water-plaster mix inside Container D is then subjected to stirring motion consequent to which the mix is ready to be poured into a mould.

Advantageously, mixing of water and plaster (and or adhesive) achieved through the device according to the present invention is a lot more steady, even and homogenous, while keeping dust levels to a minimum in comparison to the approaches known in the art. The present device enables a minimal amount of mixing stirring motion as the plaster and/or adhesive is slowly introduced to the water. Moreover, the device is more compact, light-weight, easy to handle and operate than the prior art as well as creating less wastage of the plaster and or adhesive during the process of mixing.

The scope of the present invention is not limited to the above aspects and preferred embodiments but includes all the suitable variants notably those concerning the materials used for the construction of the containers and other components of the device, the alignment of the components and arrangements for co-ordinated flow of casting plaster between the containers. Brief Description of Drawings

Figure 1 is an elevation view of the device according to the invention wherein the device comprises Container A, Container C and Container D which, in use, are stacked together in a vertical orientation. Figure 2 is cross section of a perspective view of the device of Figure 1 ;

Figure 3 is cross section of a perspective view of the device of Figure 1 additionally including a paddle;

Figure 4 is an elevation view of Container C;

Figure 5 is cross section of a perspective view of a rectangular embodiment of Container C;

Figure 6 is a perspective view of Container D;

Figure 7 is a perspective view of Container D additionally including a paddle;

Figure 8 is an elevation view of Container A; and Figure 9 is an elevation view of Container D. Detailed Description

The invention will hereafter be more particularly described with reference to the accompanying figures, which represent various views of the device according to the invention by way of example only.

As shown in Figure 1, the device 100 comprises three containers A, C, and D. In the preferred embodiment, Container A comprises a plurality of compartments 10, each compartment having sliders 12 and horizontal handles 14 for pulling the sliders 12. Each compartment of Container A holds either casting plaster or adhesive or both, present in pre-defined amounts. The number of compartments is reflective of the amount of casting plaster or adhesive, or both, required for each individual mix. The number of compartments is thus dependent on the size of the compartments and the required consistency and density of the resultant plaster cast. Container A may comprise a carrying handle (not shown in the figure) to facilitate its easy transportation. The carry handle is preferrable on the top surface of the device 100.

In an alternative embodiment, Container A comprises one compartment 10, having at least one slider 12 and at least one handle 14 for pulling the slider 12.

The plaster or adhesive or plaster-adhesive mix may be supplied in a predefined specific amount of plaster or adhesive or plaster-adhesive mixture of choice. The plaster may be provided in a box or a bag. Each box or bag is thus provided prefilled. The boxes fit inside Container A, in the most preferred embodiment, each box fits inside each of the compartments 10. The boxes may be open ended or provided with an opening mechanism such that, pulling a slider 12 of the corresponding box results in the plaster, adhesive or plaster-adhesive mix being released from the compartment 10.

Alternatively, the plaster may be provided in bags wherein each bag is provided with a predefined specific amount of plaster or adhesive or plaster-adhesive mixture of choice.

A second container, Container C comprises at its base, a sieve 16 through which the released plaster falls down into Container D. The sieve 16 may be a mesh like structure or a series of bars. Container C also includes along its periphery a rubber seal 18 to form an effective lock/seal when Container A slides on top of Container C thereby preventing inoculation of any dust from the outside. Container C comprises an orifice with a lid suitable for attachment with a vacuum. A secondary orifice may also be provided so that air can be sucked into Container C when the vacuum is active, thus allowing the vacuum to pick up any residual particles of plaster or adhesive dust which remain inside Container C, or inside Container A and C if the sliders are open, once the rest of the plaster or adhesive has fallen into Container D. Removal of residual dust prior to dissembling each of the containers means that residual dust within the containers does not escape when the device 100 is dissembled. It is the purpose of the vacuum to ensure that dust is not circulating in the air in the vicinity of the device 100 when the device 100 is dissembled. Avoidance of dust circulating in the air is important for health and safety of the user and cleanliness of the workplace.

A third container, Container D includes graduated markings 20 as which serves as a reference for filling the required amount of water, depending upon the amount of plaster or adhesive mix to be formed and corresponding to the amount of plaster released from Container A.

In a further embodiment, the device may comprise at least one paddle. The paddle may be foldable. In the preferred embodiment, the at least one paddle is lowered from the sidewalls of Container C into Container D, when Container C and Container D are assembled together. At least one slot in Container C which houses the at least one paddle is not shown in the sketches. The paddle is not visible from the outside of the device 100. The at least one paddle may move towards Container D along a pole. The paddle may rotate about the pole such that, in use, the paddle it located towards to the centre of Container D. Alternatively, the at least one paddle may travel within Container D as it travels along a track which is defined in the base of Container C. Alternatively the paddle may travel back and forth along a track or pivot point. The at least one paddles can be removed from Container C for cleaning, replacement or to use different shape or style of paddles. The paddles can be manipulated manually through levers on the outside of Container C. In a further embodiment, a power source with appropriate on/off switches etc. is provided in order to activate and rotate the paddles. In a further embodiment a timer is provided in order to ensure that the mixture in Container D is stirred by the at least one paddle for an appropriate amount of time. The timer is powered by the same power source as the paddles. Preferably the device 100 comprises 4 paddles, most preferably the device 100 comprises 2 paddles. The paddles are equally spaced about Container C such that a maximum volume of the contents of Container D can be mixed with the paddles.

It will be appreciated that the general shape of the device 100 may be substantially cylindrical or substantially rectangular. In the preferred embodiment, as shown in Figure 1 - 5 the device 100 is substantially rectangular, which in turn means that Container A, B and C are also substantially rectangular.

In an additional embodiment the device 100 may be placed inside a mechanical shaker. Use of the mechanical shaker will ensure that the contents of Container A and Container C are shaken downwards towards Container D. The contents of Container D will also be shaken which is beneficial for mixing. A mechanical shaker such as a vibration table is suitable for use with the device 100, however, it will be appreciated that a variety of mechanical shaker designs are equally suitable for use with the device 100 without departing from the inventive concept of the device 100.

For the purpose of operating the device 100 for mixing optimum or adequate amounts of plaster, adhesive, plaster-adhesive mix or any other type of suitable material which needs to be mixed through controlled mixing of a ratio of dry and wet materials, the components of the device 100 are first assembled such that Container D is first pre filled with required amount of water (or other fluid) using a water gauge 20. Subsequently, Container C having a sieve 16, slides on top of Container D. Thereafter, Container A, pre-filled with required amounts of casting plaster and / or adhesive or other suitable particle-based solids in at least one compartment, slides on top of Container C such that the rubber seal 18 along the periphery of Container C holds Container A securely in place and prevents any dust inoculation from the outside, whilst transferring the plaster from Container A to Container C.

Following the assembly of the components of device 100, in the preferred embodiment a number of sliding doors or sliders 12 in Container A are pulled back such that the amount of plaster falling from the respective compartments of Container A into Container C is proportionate to the predefined amount of water in Container D. This results in the required amount of casting plaster, or adhesive or plaster-adhesive mix from Container A into Container C which is then transferred to Container D by shaking Container C such that the amount of casting plaster present in Container C passes through the sieve 16 located at the base of Container C to enter and mix with the proportionate amount of water already present in Container D. Once the required amount of casting plaster has been transferred through the sieve 16 of Container C into Container D, the two Containers (C, D) may be detached from each other.

The water-casting plaster mix inside Container D may then be subject to a stirring motion for a specific period of time consequent to which the mix is ready to be poured into a mould.

Alternatively, once the required amount of casting plaster has been transferred through the sieve 16 of Container C into Container D, the paddles are lowered from Container C into Container D and the paddles then mix the contents of Container D whilst the entire system is sealed. Preferably, the paddles are powered through an external power source (such as standard household electricity) and their motion can be controlled, stopped, started, timed etc.

In the preferred embodiment, the at least one paddle is stored in the sidewall of Container C. When the paddle is required, a switch activates the paddle to be released from the sidewall of the Container C. The paddle may be released though a sliding mechanism or the paddle may pivot down from the sidewall to a point whereby it is sitting inside Container D. When the paddle is in position in Container D, it may rotate within Container D or move along a groove in Container C (thus moving up and down through Container D) such that it causes agitation and mixing of the contents in Container D. The paddle may be mechanised or manually controlled.

In the preferred embodiment, the paddle slides out of the walls of Container C such that it remains connected to Container C but the paddle is now located in Container D. The paddle then rotates such that it is located in the middle of Container D. As the paddle is still connected to Container C, it moves around the track in the walls of Container C thus mixing the contents of Container D. When the mixing sequence is finished, the paddle rotates back into its original position and is ready to slide back into the sidewall of Container C. The paddle is removeable which enables cleaning and changing of the paddles as appropriate. In the embodiment wherein Container C is substantially cylindrical, the paddle, in particular the blades of the paddle, may be curved in order to correspond to the sidewall of Container C in which they are stored.

In the embodiment wherein Container C is substantially rectangular, the paddle, in particular the blades of the paddle, may be square or rectangular and sheet-like in appearance in order to correspond to the sidewall of Container C in which they are stored.

The present device 100 offers significant advantages in that it is more compact, light weight, easy to handle and operate and allows lesser wastage of casting plaster than the devices known in the art for mixing purposes. The device 100 also prevents any casting plaster from escaping which is important for health and safety of the user and cleanliness of the workplace. The device 100 also measures and mixes correct ratio of water to casting plaster to form a plaster mix of desired consistency.

It will be appreciated that the invention is not limited to the specific details described herein, which are given by way of representations and examples only and various modifications and alterations are possible without departing from the scope of the invention as defined in the appended claims.