The actual sealing chemistry is a moisture curable product that is delivered in either a water or solvent carrier.  The carrier is designed to evaporate away leaving the sealing compound to cure and seal the pores.  Both product types can work, the difference is in the ease of application.  Solvent borne products can be applied in a quick wipe-on/wipe-off manner.  Waterborne products can require more care in removal of the excess.  If the excess material is not removed it will bond to the top of your stone and create a dulling or hazy film appearance.  Unfortunately, once this has occurred you will need a professional craftsman to remove and re-apply the sealant.