A composition comprising gypsum plasticized by a polymer and containing gypsum in the range of about 40% to about 90% by weight. In a preferred embodiment the polymer is polyurethane. A wide variety of applications of the composition are described.

FIELD OF THE INVENTION 
This invention relates to a composition comprising gypsum plasticised by a 
polymer. 
DESCRIPTION OF THE PRIOR ART 
Gypsum, which is the dihydrate of calcium sulphate, is a widely available 
compound. It is chemically inert. It is useful in the production of 
plaster and wallboard, the latter probably being the largest use of 
gypsum. Portland cement uses large quantities of gypsum. In agriculture, 
gypsum serves as a soil conditioner. Wallboard comprises a core of gypsum 
sandwiched between layers of paper. Although it is widely used, it does 
have disadvantages. It is not resistant to cracking nor to water. Although 
there are procedures available in the art to avoid these disadvantages, 
the known techniques are relatively expensive. 
There is an increasing concern in society about the use of materials that 
are environmentally unacceptable. For example, in Canada there has been 
concern concerning the use of urea-formaldehyde foams in insulation. 
Largely because of incorrect polymerisation, formaldehyde was introduced 
into the air in private homes insulated with urea-formaldehyde foams, 
necessitating the expensive removal of these foams. There is, in any 
event, a far greater consciousness concerning the use of environmentally 
acceptable compounds in general than has previously been the case. 
There is thus a need for producing a material of wide application that is 
environmentally acceptable. The material should not be toxic in any way 
and, as such, useful about the home and in the construction of the home. 
In this regard gypsum is considered ideal. It is a simple inorganic 
compound that is not toxic. However, the existing methods of treating 
gypsum, for example in the production of wallboards and the like as 
discussed above, have the disadvantages that the compound is rigid, tends 
to be brittle and has poor resistance to water. 
Polymers are well known for their chemical inertness and wide variety of 
properties. Those properties can be varied by varying the components of 
the polymer or, in the case of homopolymers, by varying the amount of 
polymerization and thus the molecular weight of the polymer. 
Polyurethanes are polymers that include the urethane group. The urethane 
linkage is formed by a reaction of hydroxyl and isocyanate groups. The 
high reactivity of isocyanates, together with knowledge of the catalysis 
of isocyanate reactions, make possible the relatively simple production of 
a wide range of polymers starting from low to moderate molecular weight, 
liquid starting materials. 
Flexible and rigid polyurethane foams are the most widely available forms 
of polyurethane commercially available. These formulations typically 
include isocyanates and polyols with suitable catalysts, surfactants and 
blowing agents that produce the gas for foaming. 
The great virtue of polyurethanes are that they are tough, have high load 
bearing capacity, good load temperature flexibility, resistance to a wide 
range of solvents and to oxygen, ozone, abrasion and mechanical abuse. 
SUMMARY OF THE INVENTION 
The present invention seeks to provide a gypsum composition having a number 
of interesting properties. The composition is useful in the formation of 
wallboards but can also be used as a treatment for wallboards to impart 
desirable characteristics. The invention has the great advantage of 
providing a composition of great interest commercially but being virtually 
non-toxic, easy to produce and, depending on the choice of components, of 
widely varying characteristics. 
STATEMENT OF THE INVENTION 
Accordingly, and in its broadest aspect, the present invention is a 
composition comprising gypsum plasticised by a polymer and containing 
gypsum in the range of about 40% to about 90% by weight. 
The polymer may be a polyester but in a particularly preferred embodiment 
the polymer is polyurethane. 
In a particularly preferred aspect the composition of the invention is 
derived from a mixture of the components (a) a polymerisable isocyanate 
and (b) a mixture of gypsum and a polyol. 
The mixture preferably contains about 5 to 17% by weight isocyanate, the 
balance being the gypsum and the polyol. In a particularly preferred 
embodiment the polyol is a glyceride, for example a vegetable oil. The 
particularly preferred vegetable oil is castor oil. 
Any isocyanate can be used that is known in the polyurethane art to 
polymerise with hydroxyl-containing compounds. However the preferred 
isocyanate is one containing 4,4'-diphenylmethane diisocyanate (MDI) alone 
or in combination with its 2,2'-isomer or, preferably polymethane 
polyphenyl isocyanate. Preferably, the MDI comprises about 30 to 60% by 
weight of the combination. 
The mixture may include functional additives. For example, a pigment may be 
present in the amount of about 2% by weight of component (b). Pigments 
include titanium dioxide and carbon black. A wide range of pigments are 
known commercially. 
Because of the effect of water on the isocyanate it is desirable that the 
compositions include a dessicant to prevent adverse effects. The dessicant 
may be present in about 1% by weight of component (b). A typical dessicant 
is a synthetic zeolite. 
Although the composition of the invention will cure, it is preferable to 
include an accelerator to speed curing. These accelerators include 
tertiary amines, for example dimethylethanolamine (DMEA), or an 
organometallic compound, for example, dibutyltindilaurate (DBTL). 
If desired, a blowing agent may be incorporated. These blowing agents react 
with the isocyanate to produce carbon dioxide. A small volume of water can 
be added, or an alcohol. 
In a particularly preferred embodiment, the cured composition is derived 
from a mixture comprising the components (a) isocyanate and (b) gypsum and 
castor oil. Gypsum is preferably present in the range of 50 to 90% by 
weight of component (b) the balance of component (b) being the castor oil. 
Component (b) may include about 2% by weight of a pigment and/or about 1% 
by weight of a dessicant. The castor oil component is reduced in 
proportion accordingly. 
The ratio of (a) to (b) is typically in the range 14:86 to 20:80, 
preferably 15:85 to 18:82 and, in a particularly preferred embodiment, 
17:83 especially where component (b) contains 50% gypsum. Higher gypsum in 
component (b) leads to a proportional variation in component (a). 
When additives are to be added it is desirable to incorporate them into 
component (b), that is the mixture of gypsum and the polyol, preferably 
castor oil. The isocyanates are relatively reactive and thus easily 
contaminated. Therefore the introduction of the additives through the 
mixture of gypsum and polyol is considered good practice. It also reduces 
the amount of equipment required to formulate the mixture because all the 
blending is done in one piece of equipment and the gypsum and the polyol 
must be stirred with a high shear mixer to mix those essential 
ingredients. 
The composition has the great virtue of very large tolerances in the ratio 
of the components (a) and (b). An initial approach is to set the ratio of 
castor oil to isocyanate at about 2 to 3:1 to provide a good 
polymerisation. The remaining ingredients, including the gypsum, can be 
varied widely to produce a wide range of different products. For example a 
ratio of (a) to (b) of 1:5 (for 50% gypsum in component (b)) produces a 
flexible polymer that has many mechanical properties similar to wood. When 
the ratio is varied to 15:85 or even further to a 14:86 ratio the products 
are more rubbery in properties. In contrast moving the ratio in the 
direction of 20:80 produces a much harder product. In general it is not 
desirable to proceed in the direction of a hard product as this introduces 
more unreacted isocyanate groups. These may react with moisture over time 
to produce a product that becomes too brittle. Further, the isocyanate is 
the most expensive component in the mixture and, for that matter, the only 
component having any sort of toxicity, mild though it is. In these 
circumstances, the preferred range of ratio (a):(b) is 18:82 to 15:85. 
This is about a 20% variation in the amount of isocyanate, a large 
variation. 
The mixture of gypsum and polyol may have wide variations. The gypsum 
content can vary from 50% to about 90% of component (b). The latter 
produces a finished product that is about 75% gypsum and still flexible. 
In general gypsum content in the final composition is in the range of 
about 40% to about 90% by weight. The ratio of castor oil to isocyanates 
should, in any event, be kept in the range 2 to 3:1. The additives are not 
critical. As indicated they are used in small amounts and, indeed, need 
not be used at all. The dessicant is only required to overcome free 
moisture found in the ingredients. Drying the ingredients prior to 
blending eliminates the necessity for a dessicant. However, it has been 
found that adding the dessicant is the cheapest and simplest way to remove 
free moisture. 
Addition of one or more accelerators is not essential as the product will 
cure whether or not such a component is present. However, the free curing 
time is in excess of 24 hours at room temperature which for most 
commercial applications is too long. In these circumstances, accelerators 
can be used to reduce the cure time greatly. A minimum cure time has been 
determined to be about 17 seconds using dibutyltindilaurate (DBTL). This, 
of course, can be excessive in many applications. A combination of DBTL 
and DMEA has been found to produce a cure at a slower rate thus providing 
a longer pot life. 
Plasticizing oils may be incorporated if required. Electrically conductive 
material may be added for special applications and metallic flakes may be 
added for particular visual effects. Materials to resist the effects of 
ultra-violet radiation and anti-oxidants may also be incorporated. 
Further materials such as abrasives, carbonates, boron components for fire 
resistance can be added for different effects (such as higher absorbtion 
resistance strength). Cellulose and glass fibre can also be used as 
fillers. Toxins such as copper sulphate can be added to applications such 
as marine bottom parts to prevent fouling. 
The composition may include water as a blowing agent. This produces a 
gypsum based foam of high insulation ability. For example 0.2 mls of water 
will produce 300% free expansion of about 1/4 kilogram of polyurethane 
composition according to the invention. Retarders can be added if 
necessary. 
Production of the composition according to the present invention is 
straightforward. The preferred components have a number of desirable 
characteristics that make their processing into a polymer composition 
simple. The following procedure has proved useful: 
Gypsum and any other powders present are metered from hoppers using low 
speed metering screws. These powders are fed into the top of a 1750 rpm 
blending screw. Castor oil is injected into the side of the blending 
screw. The rough mixture exits the screw and enters an inclined second 
screw, operating at about 1750 rpm. 
The smooth mixture exits the second screw and is drawn into a gear pump. 
The gear pump helps clear the second screw. The finished liquid is fed 
from the pump under pressure to a storage tank. 
The isocyanate is stored separately in a lidded container. 
To produce a polymer the mixture of gypsum and castor oil is fed into a 
tank. Accelerators, pigments and the like additives may be added to the 
tank, which is stirred and recirculated through twin process pumps. 
Isocyanate is stored in a second tank. As indicated above generally there 
are no additives in the second tank and moisture from the atmosphere is 
prevented from entering. This tank is also stirred and recirculated 
through the process pumps. 
The two components from the first and second tanks are fed separately 
through a pair of gear pumps which are geared together at a pre-set ratio 
of 1 to 5 parts of isocyanate to the mixture of gypsum and castor oil. The 
gear pumps are driven by a common, variable speed drive which is operator 
controlled. The pumps serve to meter and pressurize the two parts of the 
composition when castings are being poured. When the castings are not 
being poured, the pumps recirculate the two components back to their 
respective tanks while, of course, maintaining the set 1 to 5 ratio. 
The output from the pumps enters a pair of three diverter valves which are 
operated separately. The valves either send the components to the mixer 
head or back to their respective tanks. 
The two components, the isocyanate on one hand and the mixture of gypsum 
and castor oil on the other, are brought together at a mixer head which is 
a motorized screw, operable at 3500 rpm, with inlet ports for each of the 
components. The mixer blends the two components which have been metered by 
the process pumps while the molds are being filled. 
The properties of the composition make the process extremely simple. 
The mixer is extremely easy to flush out by simply diverting the isocyanate 
back to the tank while letting the other side, with the gypsum and the 
castor oil, run through the mixer head for a few seconds. No special 
flushing equipment is required. The gypsum is soft. It has a hardness on 
the Mohs scale of about 2. It therefore does not wear out the processing 
equipment. Castor oil obviously functions as a lubricant in the process. 
Furthermore titanium dioxide can act as a dry lubricant. The dessicant 
removes any free moisture, thus avoiding the possibility of corrosion. 
There is no necessity to use expensive anti-corrosion fittings.

The following examples illustrate the invention. 
EXAMPLE 1 
41 parts by weight gypsum 
17 parts by weight isocyanate 
39 parts by weight castor oil 
2 parts by weight TiO.sub.2 
1 part by weight zeolite 
EXAMPLE 2 
The apparatus described above was used to mix a composition comprising: 
______________________________________ 
175 parts by weight gypsum 
15 parts by weight isocyanate 
39 parts by weight castor oil 
3 parts by weight titanium dioxide 
2 parts by weight zeolite 
235 
______________________________________ 
The temperature was kept below 90.degree. C. Accelerators were not used but 
could be added depending on the physical characteristics required. The 
resulting product has the consistency of bread dough. 
Physical Characteristics 
The above composition (example 1) that is before curing, had the following 
physical characteristics: 
______________________________________ 
Colour Creamy Tan 
Pot Life 100 grams at 23 Degrees C. 
Less than 20 
(easily varied) Minutes 
Recommended Cure Cycle 
24 Hours at 23 Degrees C. 
Mixed Viscosity at 23 Degrees C. 
2000-3000 CPS 
Resin Viscosity at 23 Degrees C. 
200 CPS 
Catalyst Viscosity at 23 Degrees C. 
6000-10000 CPS 
Specific Gravity (Approximate) 
Isocyanate 1.2 
gypsum & 1.4 
castor oil 
(Mixed S.G. depends on blowing) 
Mixed (Max) 1.4 
Estimated Tensile Strength 
1300 PSI 
Estimated Elongation 
100% 
______________________________________ 
The cured product had the following characteristics: 
______________________________________ 
Colour Creamy tan to yellow. 
Flexibility Easily bent with a 
programmable memory due to 
creep. 
Machinability Similar to wood; all normal 
woodworking tools can be 
used to finish the cured 
material. 
______________________________________ 
This material sands, saws, planes and nails quite easily. Tool life is high 
unless an abrasive fill is added. 
______________________________________ 
Odour This material contains no 
volatile solvents. It is a 
vegetable oil-derived 
plastic which has a 
pleasant natural odour 
prior to curing which is 
quite mild. The odour 
disappears once the 
material is fully cured. 
Fire The material is self- 
extinguishing. More gypsum 
leads to increased fire 
resistance. 
Water Resistance High resistance to water, 
sea-water, hot or cold. 
Solvent Resistance 
High resistance to most 
common petro-chemical 
solvents. One noted 
exception is p-styrene 
monomer. 
Ultra-Violet Radiation 
UV causes the material to 
become more yellow in 
colour after prolonged 
exposure. No significant 
changes to mechanical 
properties have been found. 
Maintenance Easy to clean dirty floor 
with most selvents and 
detergents. 
Adhesion Bonds to wood, concrete, 
itself, asphalt, tar and 
paints. 
______________________________________ 
General Properties 
Shrinkage and expansion is negligible. If it should be desired the product 
may be varied to incorporate expansion. For example addition of water will 
create an omni-directional expansion as carbon dioxide is produced in a 
foaming reaction. Addition of excess desiccant will cause some shrinkage. 
The curing has a mild exotherm. The amount of heat liberated during curing 
is much less than in most other two-part, or even water-cure, systems. Due 
to the mild exotherm and the lack of shrinkage, large castings and molds 
can be produced with a small number of lifts. A lift is the term used to 
describe a pour in a series of pours gravity fed into a single mold. 
The product is of desirable casting characteristics because of the ease of 
varying the cure. Cure rates can be varied by mixing different amounts of 
accelerator, as defined above and by changing ambient temperatures. 
The product has excellent detailing characteristics. That is it follows 
patterns and mold detail extremely well, producing intricate pieces well. 
The product can polymerize into itself. This means that molds can be built 
up in pieces, repairs can be made and the like. This is a very important 
characteristic in a number of applications. 
EXAMPLE 3 
The same procedure as in Example 2 was followed but the composition was: 
175 parts by weight gypsum 
17 parts by weight isocyanate 
39 parts by weight castor oil 
3 parts by weight titanium dioxide 
2 parts by weight zeolite 
The slight increase in isocyanate produced a more rigid sheet. This more 
rigid sheet could be used for flooring or roofing sheeting. It is also 
appropriate as a replacement for current gypsum wallboards in some areas, 
particularly wet areas such as in showers stalls. 
It is envisaged that chopped fibre-glass or some other known reinforcement 
material could be incorporated if there is there a high localized loading, 
for example on a roof or floor. 
Applications 
It is believed that the composition of the present invention will find 
particular application in the production of wallboards, sometime referred 
to as gypsum board. Using the composition of the present invention, boards 
can be produced that are cheap and easy to produce, fire-resistant, 
water-proof, flexible for use in curved stair-wells, walls and the like, 
able to take all standard finishes, structurally sound and easy to install 
and work. Although the present gypsum boards are widely used in 
construction largely because they are both fire-resistant and cheap and 
easy to produce, they are not water-proof nor are they flexible. There is 
not presently a single commercial product that meets all of the above 
requirements. However, the present composition is particularly desirable 
in this regard. 
Wallboard Type 1 
This aspect of the invention simply involves applying a coating of a 
composition according to the present invention onto the finished existing 
gypsum wallboard. Experiments in this regard have shown: 
The modified board is easy and cheap to produce. It is simply necessary to 
apply about 1/16 inch thick coating of the plasticized gypsum onto the 
current board on existing production lines. The material may be applied by 
spray, roll, curtain or other coating machines added to the existing 
production lines. 
The boards have excellent fire-resistance. It is not believed that existing 
ratings for gypsum boards will change. The coating is also fire-resistant 
due to the water content of the gypsum which is, of course, a dihydrate. 
The coating is water-proof. The prior art board to which the coating is 
applied is not but the coating is undoubtedly completely water-proof. 
The board can be made flexible. By wetting the back of the sheet to soften 
the gypsum, the coated sheet bends into the desired curvature. It dries to 
retain the new shape. On existing boards the paper coating tears and 
creases easily, making it difficult and time-consuming to build curved 
walls. However the plasticized composition according to the invention does 
not tear easily. It appears to have the ability to relieve internally 
stress concentration points that develop during the bending process. 
The coated board accepts all standard finishes. 
The board is structurally sound. It has the same ability in this regard as 
the prior art sheets with a marginal increase in strength due to the 
coating. 
A standard wallboard with a thin coating, approximately 0.015 inches, might 
well be an economical and environmentally attractive alternative to the 
asphalt coated exterior sheets presently being used because of their 
water-resistance. 
Type 2 Wallboard 
As a replacement for the existing boards, with their paper surfaces, the 
plasticized gypsum according to the present invention can be extruded then 
rolled as a dough-like material into finished wallboard. This approach has 
been technically successful using the following composition: 
175 parts by weight gypsum 
15 parts by weight isocyanate 
39 parts by weight castor oil 
3 parts by weight titanium dioxide 
2 parts by weight zeolite 
The composition contains about 75% by weight of gypsum and has a 
consistency similar to bread dough. The composition is made by blending 
the components together in a compounder/extruder screw with a temperature 
maintained at a level that does not exceed 90.degree. C. Addition of DBTL, 
alone or with other accelerators, may be required depending on the rolling 
mill and the extruder characteristics. The composition is rolled through a 
series of rollers then sized and cut. The product eliminates a need for 
paper or other backings although a backing may be added if desired. 
The rolling operation can be replaced by pressing. The rolling operation 
has been shown to impart consistent, bi-directional elongation of the 
dough. In contrast, the pressing operation produces uneven elongation. 
The finished sheet has excellent surface finish, is completely water-proof, 
takes all finishes, cuts, sands, machines well, is fire-resistant, takes 
nails and screws, is flexible, has good strength (approximately 1000 
pounds per square inch tensile strength) and is easy to handle. 
The above Type 2 wallboard was varied by using the following formula: 
175 parts by weight gypsum 
17 parts by weight isocyanate 
39 parts by weight castor oil 
3 parts by weight titanium dioxide 
2 parts by weight zeolite. 
The resulting sheet was more rigid and usable as flooring or roofing 
sheathing. It was also found to be a desirable replacement for prior art 
gypsum wallboards particularly in areas where water would be encountered, 
for example shower walls. 
Experiments show that chopped fibre glass, or similar reinforcements, can 
be incorporated into the material where there is a high localized loading 
expected, for example on a roof or a floor. 
The sheathing could also serve as the exposed surface on a roof and the 
same composition according to the present invention can be used to seal 
the joints and nail holes produced during the roofing process. 
Type 3 Board 
Wafer boards or chip boards are produced by squeezing wood chips or wafers 
together with an adhesive. Preferably the adhesive is water-proof. The 
finished, cured board is inexpensive and is quickly replacing plywood in 
the market place. This is largely because plywood is an inefficient use of 
wood and is also costly. 
Although the existing wafer, chip and particle boards are cheap to produce, 
such a board using the composition of the present invention has improved 
properties particularly in higher water resistance, higher fire 
resistance, smoother surface and a higher nail and breaking strength. 
In the circumstances, the composition of the present invention can be 
rolled or pressed with wood chips and would act as both the binder and the 
filler. The resulting composition has the strength of wood with a much 
smoother and sandable surface. The board using the composition of the 
present invention has better water resistance, fire resistance and is 
stronger. 
Molded Parts 
The composition of the present invention makes an excellent moldable 
composition and is desirable in the molding of trim, for example 
baseboards, crown moldings, chair rails, panel molds and detailed parts 
from long wood patterns. The patterns are typically 12 to 16 feet long, 1 
to 7 inches wide and about 1/4 to 1 inch thick. They have a flat back 
which is in contact with a wall when the trim is installed. 
To produce a mold the patterns are first dried out. This is achieved by 
heating at about 40.degree. to 60.degree. C. for a few hours. This also 
has the virtue of drying out any air bubbles as well as moisture. If the 
patterns are not dried, the finished mold will occasionally have bubbles 
on the surface which results in surface defects on any finished produced 
from the mold. 
The molds are made by nailing the pattern into the bottom wooden tray, 
about 16 feet long. The ends are blocked and a sealer coat is applied. 
Sealer coats are known. A sealer coat may, for example, be a urethane 
spray paint. A mold release is applied. Again these compounds are known. 
They are waxes or polymers with an extremely smooth surface, for example, 
silicones and polytetrafluoroethylene (PTFE). A castable material is then 
poured into the tray. The castable material, which forms a mold, is cured 
and stripped. 
A modified composition according to the present invention has been found to 
be ideal as the castable material to produce a mold. The composition was: 
about 30 parts by weight isocyanate; 
about 60 parts by weight castor oil; 
about 1 parts by weight zeolite; and 
about 2 to 4 drops per kilogram of DBTL as accelerator. 
The finished mold is generally slow cured for about 24 hours. 
Other compositions may also be used to form the mold. For example silicone 
rubber available under the Trade-mark 3110 RTV from Dow Corning makes an 
excellent mold that does not require a release agent when filled in 
production or with a similar formula. However, the cost of the silicone 
rubber is approximately 6 times that of the composition defined above. 
To produce the architectural trim, the production line uses a long series 
of roller tables along which the mold travels. The production follows the 
following sequence: 
(1) Mold release is applied to the mold, typically by spraying. A wet type 
release agent, which is waxed based, is preferred, primary due to the low 
cost and the zero delay prior to mold filling. 
(2) The mold is filled with a plasticized gypsum according to the present 
invention. The composition flows out of a mixer nozzle into the open mold 
as the mold travels past the nozzle along the roller table. 
(3) The mold is cured. Cure time may vary between 17 seconds to 1 hour, 
depending entirely on the amount of accelerator, operator needs and 
ambient temperature. Heating increases the cure rate for a given amount of 
accelerator. 
(4) The filled, cured mold travels along the roller table and into a mill 
which mills down the upper surface of the composition according to the 
present invention, that is to say that part of the molding that will 
eventually be the back surface of the trim. Milling is not essential if 
the mold filling is well controlled. 
(5) The finished trim is stripped from the mold. The mold is then returned 
to the mold release application station. The finished pieces are trimmed, 
package, inspected and shipped. They are shipped in rolls due to the 
flexibility of the composition. 
Autobody Filler 
A composition according to the present invention has proved ideal as an 
autobody filler. The following composition has been used: 
Part "A" 
about 30 parts by weight gypsum 
about 17 parts by weight isocyanate 
about 1 part by weight desiccant 
about 2 parts by weight TiO2 
Part "B" 
about 70 parts by weight gypsum 
about 39 parts by weight castor oil 
about 1 part by weight desiccant 
about 2 parts by weight TiO2 
The above composition is mixed together in proportions of about 3 parts 
Part B to 1 part A. The pastes are blended together with a putty knife or 
stirred, precisely as with current autobody fillers. The composition is 
flexible and extremely adherent to metal. 
Spray Foam 
A water blown composition according to the present invention foam is 
expanded about 300% to produce a fire-resistant insulation foam which is 
sprayable and has some fire-resistance. The foam finds application in 
commercial insulations systems, sound dampening and cavity filling, for 
example inside hollow doors or boat hulls. 
Wallboard Filler Mud 
The plasticized gypsum of the invention makes a totally water-proof paste 
which can be used for joint fillings. It can be used to fill the joints 
between wallboards, roof panels and for crack filling, plumbing repair, 
sundeck repairs, roof leak repairs and caulking. For a water-proof gypsum 
wall it is essential to have a water-proof joint filler. 
Roof Coating 
The plasticized gypsum of the invention makes a good roof coating in place 
of tar and gravel. It does not melt on a hot day nor crack or blister on a 
cold day. It remains flexible to allow for roof expansion and contraction. 
It is easy to apply by mixing and pouring or by spraying. No propane 
burners are required and oil products are not used. 
Sun Deck Coating 
The composition is used precisely as for the above roof coatings. The 
composition can be pigmented. A two-part sundeck coating kit is envisaged. 
Such a kit can be sold at a Hardware Store and the sundeck installed by 
simply mixing and pouring the composition. The composition can be applied 
by roller, brushes, trowels or the like. 
Floor Seal 
The composition can be used as an industrial covering for concrete floors. 
The coated floors have the following benefits: 
(1) Resilience. Furthermore a slight foaming, for example 20%, improves the 
resilience yet still produces a tough floor. This can reduce back-ache. 
(2) The product has some insulation capabilities. 
(3) The product has high chemical resistance when applied to concrete and 
asphalt, a particular virtue over asphalt floors. 
(4) The composition is dust free. 
(5) The composition is tough. 
(6) The composition is easily repairable. It is simply required to pour 
more of the composition into an area being patched. 
(7) The composition is inexpensive. It is estimated to be approximately a 
quarter of the cost (at the retail price level) of the current epoxy 
flooring used for industrial floors. 
(8) The composition is flexible and will thus not crack at joints. 
It is believed that a particularly desirable application will be for the 
coating for asphalt to improve the chemical resistance of asphalt floors. 
Movie Sets 
Movie props and parts can be produced in quantity using the molding 
composition of the invention. 
Ornamental Castings 
Small intricate parts are easily produced with faithful reproduction of the 
details of a pattern. 
Road Lines 
The composition of the present invention is an excellent product for making 
road lines and markers, for example nodules and the like. The advantages 
over paint include: 
(1) There is some polymerization into asphalt and excellent bond to 
concrete. 
(2) The composition is resilient which means that it will outlast paint by 
a considerable margin. 
(3) Its thickness produces a bump which can be felt by a driver. This leads 
to more alert driving and, in particular, warns a driver when the car 
reaches the edge of a lane. 
(4) The cure time can be very short, less than 1 minute. This makes it 
possible to eliminate the need to place and pick-up traffic cones during 
line painting operations. 
Polystyrene Coatings and Adhesives 
The composition has excellent coating characteristics for polystyrene. The 
foam does not break down and a good mechanical bond is formed. A smooth 
surface is easily produced and the coating is easily applied to foam 
surfaces. The resulting product can be used to make roof panels, marine 
floats, ceiling panels and wall panels. 
The plasticized gypsum also makes an excellent adhesive for bonding pieces 
of foam together and for bonding foam to concrete. It can make a good 
general purpose adhesive that can be used to bond together pieces of wood. 
Marine Use 
The composition of the invention can be used as structural material. The 
plasticized gypsum can be used wherever fibre glass or epoxy resins are 
used. It can be used as a structural material, deck coating, a hull liner, 
a bottom paint or for bumpers. For deck coatings, or indeed for any other 
floor coating, fills such as sand can be added or sprinkled on the coating 
during the curing. Crushed nut shells, for example walnuts shells, also 
perform this function. 
Wood Coatings and Bindings 
The cellulose in wood provides a number of hydroxyl groups that polymerize 
into the plasticized gypsum of the invention. This means that as a 
covering for wooden floors, or a wood binder, the material bonds 
exceptionally well. Cellulose can, indeed, be used as a filler in the 
plasticized gypsum of the invention. 
Thus the present invention provides a composition that is easy to produce, 
can be worked easily and has a wide variety of applications stemming from 
its wide variety of desirable physical properties, low cost and high 
simplicity in application.