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     Q. -   What about sidewalks and  concrete slabs with deep scores?  Can I keep them, but ensure that they are  perfectly clear of dirt and dust before staining?  Would I need to fill the  scores?  What do I fill them with?
Hello Cathi,   
    A . -  I  wouldn't suggest filling the scores, or saw cuts, unless that's the  structurally correct thing to do. They could be expansion areas and any  filler would just pop out later, or they could be water access points causing  damage and need to be filled. 
    So first, ascertain whether or  not and/or which ones should be addressed. If you do decide to fill them  then you can use a concrete patching material, mortar, or crack repair  material. Though you may want to consider using Deco-Seal. It's what they  put between a pool deck and the pool coping at the inside edge of the pool. It  allows for contraction/expansion, is custom colored at the time of application  so it can be made to blend in or stand out artistically, is topped with a  light sand covering which increases the attractiveness and the traction, and  it's fairly inexpensive. Though it will usually need maintained about every two  to three years, which can include repairs and/or complete  removal/redo.
  
    Of course, you could also use hot oil,  which would last longer, but would tend to be quite messy and much less  attractive.
  
    If you use mortar or a concrete patching  material and want to stain it as well, then you need to first know that it will  likely stain a different color from the concrete, so you should make sample  boards using a few potential filler materials, allow them to  dry, and stain them to see what the colors will be, before doing  the entire project.
  
    Once ready, you will clean the concrete  well such as powerwashing and/or scrubbing with a stiff straw scrub brush and  T.S.P. (tri sodium phosphate), rinse well and allow the concrete to  dry. 
  
    You can use leaf blowers to speed up the  drying and also prior to applying the filler material to remove any  dust.
  
    If you use a cement filler and want to  stain it also, then apply the filler material before acid staining the project.  
    If you use a non cementious filler like  Deco-Seal or caulking, that can't be stained, or if you use a cement filler  but don't want to stain it, then you should acid stain the concrete first,  neutralize and rinse, allow to dry and then apply the filler.
  
    It is highly recommended that  you seal the entire area, at least the first time, to help enhance and lock  in your new look.