I've added the first stage of mud. It is made up of squadron green putty, Liquid cement, and very fine sand blasting sand used in train modelling.
Mixed together it forms a very nice texture which can be thinned as desired.
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let me know what you think. I'm going for a medium light covering that has dried out somewhat. I'll use pigments once I've painted the model to highlight things better.
Please tell me I haven't screwed this up!
Thanks
Sean
P.S. any additional hints are welcome.