Surfaces that have been stripped of rust by a rust removal products (such as deox-C and deox-GEL) or by mechanical means, are susceptible to flash corrosion and rusting, especially in damp or humid conditions.
If you are unable to apply a primer or paint to the surface right away after the de-rusting process there are solutions to this problem.
Upon completing the de-rusting process, dry the surface with a compressed or warm air gun, or pat dry with a cotton cloth. Once dry, spray with ferrosol or atom-mac. This will protect the surface until you are ready to continue.
Degrease with white spirits and a brush before painting, cover the surface with white spirit and after brushing, remove white spirit with a lint free cloth.