Stacked limestone walls---outdoors in a garden or indoors on a fireplace---provide a note of rustic beauty to any design. Limestone can come in a variety of natural colours---grey, tan, yellow---or a combination of all three. If you want to give your limestone wall a single, unifying colour, you can stain the stone with a colourant compound, available at most landscape supply stores or online. You can also use colourants to artificially "age" limestone by adding telltale streaks of green to represent the development of moss.
- Skill level:
Things you need
- Stone colourant products (base colour and green)
- Power sprayer
- Two spray applicator bottles with adjustable nozzles
- Watch or timer
- Clean cotton rags or cloths
- Garden hose
Purchase stone colourant products, not "color enhancers." Colour enhancers revive the stone's natural colours. You want to change the colour altogether. Read the package carefully so you're sure to get the right product. You can use colourants meant for "concrete" staining on limestone walls.
Study the directions for the product carefully before proceeding and gather all the recommended tools for the job ahead of time. Limestone is extremely porous and you won't have time to "stop" the recoloring process to fetch another tool.
Clean the limestone surface with a power sprayer, with the sprayer head set on "broad" or "wide." Don't use a fine setting: you could accidentally etch the stone. Let the stone dry completely before proceeding, unless your product directions tell you to apply the product to wet stones.
Pour the "base color" (grey, tan or yellow) colourant product into a clean spray applicator bottle. Set the nozzle to "wide." Spritz the product onto a test stone (or a less visible area of the wall or walkway). Let the product settle onto the limestone for a few minutes, or according to the product recommendations. Since limestone is so porous, longer "setting" times will usually increase the colour effect. Wipe off any excess colourant with a thirsty fabric rag.
Evaluate the effect of this first trial "setting" time. If the colour isn't deep enough, apply a second coat and let it set longer before wiping it off. If the colour is too deep, reduce the setting time and test this theory on a second trial stone.
Colour only two or three stones at a time across the wall until the entire project has been treated with the base colourant. Let the colourant dry completely.
Pour a green-toned colourant product into another empty spray bottle. Set the nozzle on "narrow" or "fine." Choose areas along the wall where you want to apply faux moss to the surface of the stones. To make this choice, think of the behaviour of real moss. Real moss on a wall follows a path of water as it flows down the face of the wall and so cascades down stones in an inverted pyramidal shape. The top stones on the walls will have the most moss, and the width of the moss will taper as the moss goes lower on the wall.
Spray the green "aging" faux moss colour on the stones and let the colour set for a predetermined amount of time. Wipe away any excess. Let the colour dry.
Gently rinse the limestone with a garden hose, not a power sprayer. You will likely remove the colourant you just applied if you use a power sprayer.
Apply a sealant if your colourant product recommends it, and do so according to the product directions. Sealants generally retard fading of colours due to water and sun.
Tips and warnings
- Look at pictures of aged limestone walls for keys to what aged limestone looks like.
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