Sandcastle

Sand art is the practice of modelling sand into an artistic form, such as a sand brushing, sand sculpture, sandpainting, or sand bottles. A sandcastle is a type of sand sculpture resembling a miniature building, often a castle.

The two basic building ingredients, sand and water, are available in abundance on a sandy beach, so most sand play takes place there, or in a sandpit. Tidal beaches generally have sand that limits height and structure because of the shape of the sand grains. Good sculpture sand is somewhat dirty, having silt and clay that helps lock the irregular-shaped sand grains together.

Sand castles are typically made by children for fun, but there are also sand-sculpture contests for adults that involve large, complex constructions. The largest sandcastle made in a contest was 18 feet tall; the owner, Ronald Malcnujio, a five-foot-high man, had to use several ladders, each the height of the sandcastle. His sculpture consisted of one ton of sand and 10 litres of water to sculpt.

Sand grains will always stick together unless the sand is reasonably fine. While dry sand is loose, wet sand is adherent if the proper amounts of sand and water are used in the mixture. The reason for this is that water forms little "bridges" between the grains of sand when it is damp due to the forces of surface tension.

When the sand dries out or gets wet, the shape of a structure may change, and "landslides" are common. Furthermore, the mixture of fine (mostly sharper) and coarse sand granules is very important to achieve good "sand construction" results. Fine granules that have been rounded by the natural influences of seas, rivers or fluvials, in turn negatively influence the bonding between the individual granules as they more easily slide past each other. Research is thus necessary to find the most suitable sand to achieve an optimal, landslide-free construction.

Shovels and buckets are the main construction tools used in creating sand castles and sand sculptures, although some people use only their hands. A simple sand castle can be made by filling a bucket with damp sand, placing it upside-down on the beach, and removing the bucket. For larger constructions, water from the sea to mix with the sand can be brought to the building site with a bucket or other container. Sometimes other materials, such as pieces of wood and plastic are constructed to hold piles of sand in place and in specific shapes - these are called forms.

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Wikipedia