Blue print
In addition to the plaster cast , the blue cast is a method for taking measurements of the foot when making custom insoles. The patient steps into a box with the blueprint with his foot . This in turn acts like an ink pad . The paper is placed on top. You can see the surfaces in contact with the ground, graded according to stronger (darker) or lesser (lighter) pressure on the paper. This procedure mainly depends on the outline of the foot under stress. (Note: The loaded feet are always longer than in the unloaded state, approx. 0.5 to 0.75 cm, therefore, and because of the shrinkage tolerances of the positive cast, it makes sense to also make a blue cast with the cast.)