All of the following procedures are recommended in dark
room processing except:
One of the most important requirements is that the darkroom be lightproof. If it is not, stray light can cause film fogging and loss of contrast. To make the darkroom lightproof, a light-tight door or doorless maze (if space permits) is used.
SAFELIGHTING
The processing room should have both white illumination and safelighting. Safelighting is low-intensity illumination of relatively long wavelength (red) that does not rapidly affect open film but permits one to see well enough to work in the area. To minimize the fogging effect of prolonged exposure, the safelight should have a frosted 15-watt bulb or a clear 7.5-watt bulb and should be mounted at least 4 feet above the surface where opened films are handled.
X-ray  films  are  very  sensitive  to  the  blue-green  region  of  the spectrum and are less sensitive to red wavelengths. The red GBX-2 filter is recommended as a safelight in darkrooms where either intraoral or extraoral films are handled because this filter transmits light only at the red end of the spectrum. Film handling under a safelight should be limited to about 5 minutes because film emulsion shows some sensitivity to light from a safelight with prolonged exposure. The older ML-2 filters (yellow light) are not appropriate for fast intraoral dental film or extraoral panoramic or cephalometric film.
 Reference: White and Pharoah's Oral Radiology Principles and Interpretation 7th edition page no 70, 71
Use of high intensity and short wavelength light (Red)
Light is placed 4 feet above the processing tank
Light is placed behind the processing tank
X-ray of red filter GBX-2 is used