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CASTING 2000 MIX
TECHNICAL BULLETIN
(Updated July. 2000)
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PRODUCT OVERVIEW
WINTERSTONE Casting 2000 is a new formulation suitable for a variety of art-related and commercial casting applications, and architectural restorations. It has improved strength and shrinkage resistance with fine detail reproduction capabilities. It is ideal for casting of thin shell multi-dimensional or baf-relief forms either by slush casting or lay-up.
WINTERSTONE Casting 2000 is a dry white powder a complex multi-component cementitious mixture which when mixed with a nominal amount of water and cast into a mold sets into a stone hard material with faithful reproduction of detail. The hardening process is a result of the internal reactions taking place between the water and the various components. The inclusion of proper reinforcing mesh, either metallic hardware cloth or alkali resistant fibreglas, as backing to the casting; or chopped strand (e.g. fibreglas, polypropylene) mixed integrally into the back-up mixture produces a structurally sound composite shell with increased strength characteristics. This surface shell combined with proper back-up reinforcing rods ( particularly in larger 3 - dimensional sculptures or bas-relief panels ) results in a light and efficient overall structural system and allows considerable freedom in complexity and intricacy of shape.
WINTERSTONE can be integrally pigmented during the mixing stage or can be externally patinated after de-molding. Hardened WINTERSTONE can be refined with abrasives and polished if necessary. Finished and sealed WINTERSTONE is weather stable and may be founded in an outdoor environment. With proper care and maintenance it can be expected to last many years.
PREPARATION
WINTERSTONE is supplied as a one part dry mix. It has at least a one year shelf life provided it is kept in a sealed container in a dry place.
WINTERSTONE is easily prepared by mixing water in the ratio of 16
to 17 parts by weight of water to 100 parts by weight of dry mix. ( This
is equivalent to an approximate volumetric measure of 19 to 20 parts
of water to 100 parts of loose dry mix. The dry mix in the supplied
bag is generally compacted due to shipping and handling and should be fluffed-
up into a loose condition before measuring volumetrically. ) Care should be
taken in the measurement process as the WINTERSTONE mix is extremely
sensitive to very small differences in the quantity of mix water. It should
be kept in mind that the strongest and most durable end product results from
using as little mixing water as possible. One pound of dry mix produces approximately
17 cubic inches of mixed product.
Generally, even for small sculptures, several pounds of mix is required and
therefore mixing with an electric or air-powered tool is recommended ( e.g.
1/4 electric drill with propeller type mixer attachment ).
Place the water and the dry WINTERSTONE into a suitably sized plastic
container ( e.g. 2 gal. pail ) and mix thoroughly with the mixing tool for 1
1/2 to 2 minutes then let the mix rest for 1 minute, and then re-mix for
at least another 1 minute.
CASTING TECHNIQUES
WINTERSTONE may be cast in numerous types of molds . The type of mold and mold material to be used generally depends on the type, size, shape, and intricacy of the item to be cast, and this is well covered in numerous technical mold literature. The critical aspect in selecting the appropriate mold for casting WINTERSTONE is that the mold in no way takes water away from the mixture once it is applied or poured.
The most suitable are polyurethane and silicone type molds. For instance, Smooth - On molding compounds such as Brush-On Series, PMC121 Series and Evergreen Series provide superior molding capabilities and full compatibility for casting applications with WINTERSTONE . Releasing agents may be required depending on the choice of mold.
The mixing of WINTERSTONE should be done in two or more batches. The
initial batch should be small enough to use within its open pouring time
and yet sufficient to cover the mold surface or face up to a thickness of
1/16 - 1/8 inch. The open pouring time of the casting mixture is
of the order of 5 minutes . An additional few minutes of open time if required
can be achieved with occasional agitation of the mixture in the mixing container.
In all casting techniques care should be taken to remove entrapped air from
the mixture. This can be done by pouring or applying the face mix into the
mold and slushing, brushing or vibrating. Allow the face mix to thicken and
set but still be finger-print sensitive and damp. Generally this should
take about 8 to 10 minutes.
During this interval another batch of mixture can be prepared. This back-up
mix can be applied in different ways depending on the size and intricacy of
the piece being cast and the accessibility into the mold. Chopped strand (e.g.
fibreglas, polypropylene) may be incorporated into the mixture ( up to 1 % by
wt. ) and then slush cast in a manner similar to the face mix.
Another option is to use short lengths of fibreglas mesh, impregnate these with
mixture and build onto the back of the face mix. In either case the build-up
can be repeated layer upon layer until the desired thickness is achieved. The
overall thickness need not be greater than 1/4 to 3/8 inch for smaller
pieces and 1/2 - 3/4 inch on large life-size castings, depending on the
shape and size, and back-up reinforcing. Care should be taken throughout the
process to ensure that the thickness is relatively even and consistent.
In casting some sculptures by lay-up such as large sculptures using multi-segmented
molds or haut-relief type panels, run-off on vertical surfaces might be a problem.
In such cases the use of a 50:50 mixture of Casting 2000 and Sculpting
Mix is recommended. It is placed in the mold and compacted by hand or trowel.
Mixing and application procedures as outlined in the WINTERSTONE
Regular Sculpting Mix Technical Bulletin should be followed. The demolding
of the sculpture when using this combined mixture will vary from 10 - 24
hours depending on the characteristics of both the sculpture and the mold.
The techniques and materials mentioned in the foregoing is sufficient to form
the basis of approach to any type, size or complexity of sculpture. The final
choice of the process to be used remains with the sculptor/caster.
CURING
At the completion of the casting process the entire piece should be wrapped with plastic sheeting to maintain the moisture and cure properly. The piece may be demolded generally after 4 to 16 hours and will depend on the shape and fragility of the detail and on the flexibility of the mold material. If the piece is demolded before the recommended 24 hours of moist curing, it should be immediately re-covered in plastic sheeting. The dampening and plastic covering to preserve moist curing conditions for the initial 24 hours is critical to the development of the overall strength and durability of the finished product. After the initial 24 hours of moist curing the piece should be uncovered and allowed to air dry. The air-drying triggers other internal reactions leading to further strength development.
FINISHING
Regardless of the type of mold or casting technique used, some minor imperfections may occur which require a certain amount of repair work. the repairs should be carried out before applying any finishing or sealing coatings. Before starting with this work, any mold release residue should be removed with the appropriate solvent as may be recommended by the mold supplier, or by fine sanding. Seam feathers can be sanded down carefully. Any air holes or other surface defects may be patched with some WINTERSTONE Casting 2000 which has been freshly hand-mixed in a small batch to a creamy consistency. Surface defects should be roughened slightly and dampened with a light fog spray before applying the mixture. Air holes may be readily filled by rubbing the mixture into the surface using a fine sponge. Allow to cure for 24 hours before fine sanding.
After 2 to 3 days of air-drying give the piece a light water spray and inspect the surface closely. Occasionally irregular lines may appear which although invisible to the naked eye when dry, become evident on wetting and are due to the differential surface absorption along the lines . These lines are very fine shrinkage cracks which are generally the result of the use of excess mixing water and/or inadequate curing. A creamy mixture of the Casting 2000 should be rubbed well into these areas with a fine sponge and the excess rubbed off. After curing follow up with a very light fine sanding before applying any sealers.
Many kinds of surface coatings can be applied to hardened WINTERSTONE with excellent adhesion, including water, oil or solvent based materials. The sculpture must be thoroughly dried if coatings other than water based materials are applied. On completion the piece should be sealed with two coatings of sealer, particularly if it is to be exposed in an outdoor environment. Breathable sealers are recommended, either water-based acrylic, silicone or siloxane. This may have to be repeated every few years on outdoor pieces and will depend on the sealer used and on the severity of the climatic conditions and airborne pollutants.
PIGMENTATION
WINTERSTONE can be integrally pigmented to brilliant or soft colours. In general, pigments that are suitable for use in cement mortars such as iron oxides (reds, yellows, browns, blacks, terra cottas) can also be used in WINTERSTONE. All pigments added should be pure, dry powders and not liquid dispersions or mixtures with other fillers. In general, do not use more than 5 parts of pigments per 100 parts of dry WINTERSTONE. To check whether a pigment is compatible, try it first in a small test batch of WINTERSTONE. If adding the pigment causes the WINTERSTONE to set either too quickly or too slowly, the pigment is not compatible and should not be used.
WEATHERABILITY
The life span of WINTERSTONE sculpture placed in an outdoor environment cannot
be assigned accurately because WINTERSTONE as we know it is not old enough to
provide us with examples of any age. Modern buildings and structures constructed
of materials based on present day cement/concrete technology generally have
an estimated life span of 100 years. It is safe to assume that WINTERSTONE sculpture
utilizing similar but more complex and up-to-date technology/materials should
last that long. Proper sealing and maintenance optimizes the sculptures outdoor
performance.
Extra care and caution should be taken throughout the whole casting process
for any sculpture or ornamentation which is subjected to the climatic rigors
of an outdoor environment. All aspects of the process are critical : using minimal
mixing water, proper and adequate curing, proper embedment of reinforcing mesh,
and particularly final surface finishing and sealing.
ADDITIONAL TECHNICAL NOTES
Casting 2000 may be combined in varying proportions with the Sculpting Mix to suit specific project requirements or sculptors techniques. By also varying the amount of mixing water the sculptor/caster has considerable latitude of choice with respect to working consistency, pot-life and set times.
Example:
50/50 mixture of Casting 2000/Sculpting Mix @ approximately 14 parts water - produces a workable mixture with approximately 20 minutes pot-life and which sets within one hour. Ideal for fast-paced rough build-up of a sculpture.50/50 mixture of Casting 2000/Sculpting Mix @ approximately 16 parts water - produces a workable mixture with additional open time and a workable consistency for lay-up casting. Ideal for large multi-segmented mould application.
The Material Safety Data Sheet for this product should be read before using and is available upon request.
This product is safe to use with proper handling and precautions. Read and follow directions carefully.
IMPORTANT- The information contained in this Technical Bulletin is
considered accurate. However, no warranty is expressed or implied
regarding the accuracy of the data, the results to be obtained from the
use thereof, or that any such use will not infringe a patent. User
shall determine the suitability of the product for its intended application
and assumes all risk and
liability whatsoever in connection therewith.