Radiography in Modern Industry - Kodak

Chapter 13: Special Processing TechniquesThere are a number of special techniques useful in the processing of x-ray films. Some areapplicable to both manual and automatic processing and others only to manual. Certainradiographic installations may use one or more of these routinely; others may employ them ascircumstances warrant.Intensification Of Underexposed RadiographsEvery industrial radiographic department occasionally encounters a radiograph that has beenunderexposed, either through an oversight or because of insufficient machine capacity. If theradiograph cannot be repeated because the time required for proper exposure would beprohibitively long, or if the item is no longer available, the underexposed negative can in manycases be salvaged. Chemical intensification of the completely processed film may, under certaincircumstances, result in a speed gain of a factor of 5 to 7, while still retaining acceptableradiographic quality.Films may be intensified immediately after fixation, or after they have been fully washed anddried. In either case, the films are washed in running water for 5 to 10 minutes, hardened inKODAK Special Hardener SH-1 (formula given below), and again washed for 5 minutes.KODAK Special Hardener SH-1Avoirdupois, U.S. LiquidMetricWater 16 fl oz 500 mLKODAK Formaldehyde, about 37% solution byweight2 1 / 2 fl oz 10.0 mLKODAK Sodium Carbonate (Monohydrated) 90 grains 6.0 gramsWater to make 32 fl oz 1.0 litreThey are then treated, one at a time, for up to 10 minutes in KODAK Intensifier In-6. The workingintensifier is mixed from the stock solutions (formulas given below) by taking one part of SolutionA, and adding in succession two parts of Solution B, two parts of Solution C, and finally one partof Solution A. The order of mixing is important and should be followed. The hardening andintensification can conveniently be done in trays. The film should be agitated frequently duringintensification, after which it is washed for 20 to 30 minutes in running water and dried normally.WarningAlways add the sulfuric acid to the water slowly, stirring constantly, and never the water to theacid; otherwise, the solution may boil and spatter the acid on the hands and face, causing seriousburns.The water used for mixing the solutions for the intensifier should not have a chloride contentgreater than about 15 parts per million (equivalent to about 25 parts sodium chloride per million);otherwise, the intensification will be impaired. If in doubt as to chloride content, use distilledwater.