Looking at installing cedar siding (shakes); we want the natural weathering look but are we making a mistake if they are not purchased pre-treated.

I take it by natural you mean the grayed weathered look. The Cabot stain company has a weathering stain that will give you this look quicker than just plain weathering will do but it still will protect the wood and keep it from curling and cupping.

thank you for responding; how often would the stain need to be re-applied and should it be put on both front and back sides of shingles?