Model scale tests have been undertaken to find a model material which can give scaled fragmentation in sublevel caving blast models where the purpose is to study the swelling and fragmentation of the burden when blasted against waste rock and also to study the gravity flow of the blasted burden when being discharged into the drift. To achieve a wished Rosin Rammler distribution of the blasted material in the blasted model, it was shown necessary to introduce weakness plans of different size and stochastic orientation in the model material. Crushed microscopic glass plates or coarse magnetite grains were used for that purpose with success