As a guide, an exposure of one second to a 25 watt incandescent lamp at two metres distance at around the end of the first minute of a 2-minute development can produce acceptable results. If the exposure is made with the developing print still in the tray of developer, it is important to stop agitation at least 10 seconds prior to exposure to allow any bubbles on the surface to disperse and to ensure that the print is lying flat. Pseudo-solarizing colour prints is more difficult because of the more careful control of temperature and timing that is required and because most amateur processing is undertaken in a processing drum rather than a dish. As lightsource also an enlarger without negative in the carrier can be used.