Annmarie and Holly,
I couldn't help but chime in here. How the concrete is prepared for staining is a function of the type of stain being used, old or new concrete as well as interior or exterior location. Not knowing the specific stain type you will use, acid based vs. water based, WILL affect the concrete prep treatment REQUIRED. This type of information is readily available from stain manufacturers. If memory serves acid washing concrete is not recommended for acid based stains. I haven't specified concrete stains in quite a while but I can't recommend strongly enough the need to prepare the concrete properly. Past conversations with concrete sub-contractors (who would also be a great source of definitive information) usually focused on prep work vs. actual stain application. This is because the preparation is actually far more critical to achieving an acceptable finished product.
Hope this helps.
