The workplace should be well illuminated, preferably by indirect natural light. It should be air-conditioned or heated according to the climate. In the latter case, a closed convector heater or radiator should be chosen that can be operated without fire hazard. The doors should open outwards and all fire and safety regulations should be respected.

The floor covering should be continuous, fireproof and easily washable. The walls, the furniture, and the frames of the windows and doors should also be easily washable. All these elements should be of a neutral colour (preferably white or pale beige) to facilitate the evaluation of colour reactions.