Ink-jet is a robust method for the production of tactile maps and diagrams for people with visual impairment and its use is likely to proliferate. As with visual images, tactile map features can be evaluated by their engineering properties such as mechanical robustness, longevity and precision. However, the quality of the tactile structure can also be evaluated on the basis of psychophysical parameters that can be used to measure the perceptual qualities of a tactile map. The classical retinal variables of shape, size, value, orientation, hue and texture are reworked to come up with a set of haptic variables; size, shape, elevation, texture, line profile and symbol location, by which the usefulness of a tactile map can be gauged. Examples of each of these variables have been manufactured and samples are presented for demonstration and critique. By better understanding the haptic processes it is intended that the amount of information that can be conveyed to a tactile map reader can be maximised, while the engineering resource of the map and its manufacture can be minimised.