The last stage is adding pigments in order to blend the barrel into its surroundings. These drums were destined for the Opel Blitz which was serving with the Afrika Korps therefore AK Interactive Desert Sand and Mig Productions Beach Sand were used. Taking an old soft brush, small amounts of dry pigments are worked into the surface concentrating in recesses where dust would accumulate.
These techniques will really add life to your model by adding extra detail to the piece making it more attractive to the eye. As you can see from the videos, armed with fast drying enamels (and a hairdryer) the process is quick and with a small amount of practice quite straight forward.