A jigsaw puzzle is a tiling puzzle that requires the assembly of numerous small, often oddly shaped, interlocking and tessellating pieces. Each piece usually has a small part of a picture on it; when complete, a jigsaw puzzle produces a complete picture. In some cases more advanced types have appeared on the market, such as spherical jigsaws and puzzles showing Optical Illusions.
Jigsaw puzzles were originally created by painting a picture on a flat, rectangular piece of wood, and then cutting that picture into small pieces with a jigsaw, hence the name. John Spilsbury, a London mapmaker and engraver, is credited with commercialising jigsaw puzzles around 1760. Jigsaw puzzles have since come to be made primarily on cardboard.
Typical images found on jigsaw puzzles include scenes from nature, buildings, and repetitive designs. Castles and mountains are two traditional subjects. However, any kind of picture can be used to make a jigsaw puzzle; some companies offer to turn personal photographs into puzzles. Completed puzzles can also be attached to a backing with adhesive to be used as artwork. Tetris could be considered a virtual jigsaw puzzle.
During recent years a range of jigsaw puzzle accessories including boards, cases, frames and roll-up mats has become available that are designed to assist jigsaw puzzle enthusiasts.
Most modern jigsaw puzzles are made out of cardboard, since they are easier and cheaper to mass produce than the original wooden models. An enlarged photograph or printed reproduction of a painting or other two-dimensional artwork is glued onto the cardboard before cutting. This board is then fed into a press. The press forces a set of hardened steel blades of the desired shape through the board until it is fully cut. This procedure is similar to making shaped cookies with a cookie cutter. The forces involved, however, are tremendously greater and a typical 1000-piece puzzle will require a press which can generate upwards of 700 tons of force to push the knives of the puzzle die through the board. A puzzle die comprises a flat board, often made from plywood, which has slots cut or burned in the same shape as the knives that will be used. These knives are set into the slots and covered in a compressible material, typically foam rubber, the function of which is the ejection of the cut puzzle pieces.
New technology has enabled laser-cutting of wooden jigsaw puzzles, which is a growing segment of the high-end jigsaw puzzle market.
Jigsaw puzzles typically come in 300-piece, 500-piece, 750-piece, and 1,000-piece sizes, however the largest commercial puzzle has 32,256 pieces and spans 544 cm by 192 cm. The most common layout for a thousand-piece puzzle is 38 pieces by 27 pieces, for a total count of 1,026 pieces. The majority of 500-piece puzzles are 27 pieces by 19 pieces. Children's jigsaw puzzles come in a great variety of sizes, rated by the number of pieces. A few puzzles are made double-sided, so that they can be solved from either side. This adds a level of complexity, because it cannot be certain that the correct side of the piece is being viewed and assembled with the other pieces.
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