i used caustic ( castrol super clean ) followed by washing it in hot water, then an acid nuetralizer ( wheel acid) then a cold water rinse, with lots of brushing with a stiff plastic brush and got a decent looking , and clean, block. i've blasted a few blocks over the years and its REALLY tough to get all that abrasive media out of all the nooks and crannies. especially if there is any residual oil left on it. if you have to have that "new" cast look. i would reccomend "peening" the block with #8 glass bead at around 30-40 psi. it'll seal up all the pores and give any metal a nice sheen. anything media that cuts just opens the pores up and makes it more prone to corrsion