Water soluble developers SHALL NOT be used on parts processed with water
washable, Method A, fluorescent penetrants or any visible-dye penetrants, unless
Wet, soluble developer in open immersion tanks is subject to evaporation. As the
water evaporates, the developer concentration increases. A solution concentration
level should be established and maintained by the addition of water and dry powder.
The developer may be applied by spraying, flowing, or immersion. If the immersion process is used, the part should
not remain in the solution any longer than required to provide complete coverage. The developer may be applied to
parts while they are still wet from the water wash after penetrant removal. Care must be exercised to prevent
entrapment of soluble developer in the part cavities or concave surfaces (pooling). The developer should wet the part
surface with no water break areas after application. After the developer is applied, the parts must be oven dried, since
room temperature evaporation is too slow. The developing action does not start until the developer is dry.
a. The primary advantage of water soluble compared to water suspended developer is the elimination of
the need for agitation to keep the particles in suspension.
b. The coating does not produce streaks or runs that often occur with wet suspended developers.
c. The developer particles, being soluble in water, are very easy to remove during postcleaning.
Water soluble developers are subject to bacterial growth. The susceptibility is
dependent on the geographical area and the type of local water. The first indication
can be a foul odor or visible growth.
a. Water soluble developers contain wetting agents that can act as penetrant removers and must be
carefully used. This removal action is accelerated with water washable penetrants. Therefore, water
soluble developers SHALL NOT be used on parts processed with water washable penetrant.
b. Even though a thick, white coating is produced, water soluble developers do not function well with
visible-dye penetrants. Water soluble developer SHALL NOT be used with visible-dye penetrants.
c. Like the wet suspendible developers, the biocides in water soluble developers only delay bacterial
growth. The water soluble developers must be discarded when bacterial growth is noticed and the tank
or container completely disinfected prior to mixing a new solution.