ALL STACK STONE MUST BE SEALED WHEN LAYED EXTERNALLY AND NOT UNDERCOVER. Wether you use a penetrating or surface sealer to achieve the final result you are after is up to you BUT it must be sealed and resealed every 12 months. Also natural stone can naturally discolour overtime due to mineralisation or oxidation, this is a natural effect that will occur. Prior to installation of your stack stone always ensure batches ( crates) of stack stone are shuffled to ensure even colour distribution over the entire job. This will mean opening every box of stack stone prior to starting installation to ensure an even colour distribution is achieved when installation is commenced. We recommend the use of MAPEI adhesive (follow manufacturers guide lines for usage) for installing all stacked stone and that you follow the Australian standards for installation of all stack stone. Mechanically fixing of Ledgestone especially is expected every 2 mtrs in height, this practice should also be applied to the lesser weight stack stones as well.