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Do Slate Patio Slabs Scratch?

We had friends who installed a black slate patio and it looked amazing – for about a month until the kids and outdoor furniture legs scratched the hell out of it. It still looked good, but the scratches were frustrating.

Slate patio slabs do scratch, and darker slates show them more visibly. To avoid scratching, choose high quality, dense slate that’s less porous and doesn’t absorb much water. This slate has a harder surface that’s less prone to flaking and deep scratching, which can be maintained more easily.

Let’s jump in and look at why slate scratches – and what we can do about it – and find out whether it really is a good choice for patios.

Do Slate Patio Slabs Scratch Easily? 

The short answer is – yes, it can

Slate began as a shale – a sedimentary rock made of very fine grains of quartz (silica) and other minerals. Shales, or mudrocks, are deposited in water in quiet settings, like the bottom of the ocean. Then, the shale is buried and subjected to heat and pressure. It metamorphoses into slate. It takes hundreds of thousands – or millions – of years to turn shale into slate.

Slate tiles do get scratched and scratches tend to show more on slate’s dark colors. To decrease the number of scratches, first try to choose slates that are higher quality – harder. Slates are not all created equal.

Key questions to ask are: is the slate outdoor grade (not indoor), where is the slate from and does it have low water absorption? Water absorption is important because it can cause the slate to cleave or flake. In freezing climates, water absorbed by the slate freezes and the slate can crack. 

Slates come from all over the world. Natural stone experts say that slate from Vermont and New York is smoother and denser, with low water absorption.

Slate from Portugal, Wales and the U.K. are high-quality and dense. Chinese (“Mandarin”) and Indian slate is colorful but soft and tend to absorb water. Brazilian slate is colorful, dense and has low water absorption. 

If slate comes from so many places and in lots of grades – how do you choose? Before committing big bucks, ask for free samples or buy one or two of the slate tiles you are considering.

Take them home, and experiment with them. Do they scratch under a chair or heavy table? If they do scratch, will one of the treatments listed below decrease the damaged look? 

Soak the tiles in water for a day (or a week!) and try to chip off layers. If the soak water turns orange or red, there may be an iron mineral in your slates. Water pooling on the patio may turn an unsightly orange color.

Spill wine or food on the tiles, then see how well the tiles clean up with dilute dish washing soap. Walk on them and try to scuff them. If you blast them with the high-pressure nozzle on your hose, what happens? 

Lay the tiles in the patio space in your backyard and see if you like the aesthetic. Do they go with your patio furniture? Do you like the texture – the unevenness? Watch as the color changes during the day. Who knows? You may dislike your tiles – or you may love them.

Slate tile patios can be sophisticated or earthy, and they will last a lifetime – with some care.

Is Slate Good For Patios if it Scratches?

Yes! It looks fantastic. Slate tiles are a beautiful, natural and durable choice for your hardscape. Every slate tile is one-of-a-kind: from the color range to the shape of the surface. Slate tiles give the patio a unique and interesting texture, like this. A patio made from slate complements a garden’s natural beauty. 

Slate has many good qualities: strength, durability and stain resistance. It has a color range from grey to black, cyan to striking greens and purples. Flakes or thin layers of slate cleave off, giving slate a unique texture. Slate is not slippery underfoot – unlike marble and some ceramic tiles. Natural stone can enhance your home’s style, from traditional to modern.

A slate patio is not perfect. Slate’s surface is naturally uneven. Tables and chairs may wobble. For some, the uneven surface may be hard to walk on. You may not like the uneven look. Also, dark-colored slates may be hotter underfoot.

How Do You Remove Scratches From Slate? (Slate Scratch Repair)

Scratches in natural stone can blend in, or they can even add character. Other scratches look unnatural and unsightly. Linear, light grey scratches in dark grey slate stand out. Scratches in slate can be concealed or sanded out.

To conceal scratches and scuffs in slate, first try a stain – or touch up – pen. Hardware stores carry a variety of indelible pens in many colors. Stains and scuffs can be minimized by rubbing mineral oil into the scratch. The lighter colored scratch will darken. 

To get rid of scratches, use sandpaper or steel wool. Start with a fine-grit sandpaper (like 400) and gentle pressure. For deeper scratches, use harsher sandpaper or steel wool but finish with a fine grit.

Slate patio
How To Get Scratches Out of Slate Patio Slabs

Can You Pressure Wash Slate Patio?

Yes, but carefully. A good sweeping will often be enough to clean your slate patio. Full-pressure washing may be too hard on the natural stone – sending chips flying. Medium pressure hose attachments may work without any damage. Brush attachments on hoses work well.

If your patio has black spots that don’t come off with power washing, then you may have mildew. For a “green clean” solution, try a diluted hydrogen peroxide or scrubbing with baking soda. Try a mild solution of vinegar on a small moldy area. Leave the vinegar on for ten minutes. If the vinegar fizzes, dissolution is occurring, and you should use something else.

Should I Use Sealer On My Slate Pavers?

Many experts recommend sealing natural stone – but natural stones are not all created equal. Sealants work well when a stone has lots of tiny holes – pores. Flagstones are often made from sandstone, a grainy sedimentary rock that is extremely porous. 

Limestone and travertine, also sedimentary rocks, are very porous. Granite is an igneous rock and not porous at all. Marble and quartzites are metamorphic and not porous. Slate is metamorphic and not usually porous – hence the use in roofing.

Applying sealants every year is a commitment. Slates do vary in quality – so test if your slate needs sealing first.

If you live in a wet place without glaring sun, sealants may be a good choice. Try some sealant on a leftover tile and see if you like the look (sealant darkens stone). Leave it outside in the rain.

Be aware that once you apply a sealant, experts recommend a reapplication every year – some slates more often. Spill some food or wine on your test slate and compare it to an unsealed piece. Do stains come off easier?

Mother Nature can be tough on sealants. In dry, sunny climates, harsh UV rays tend to make sealants yellow, flake and peel. When this happens, the sealant has to be stripped off and then reapplied. Depending on the sealant, stripping may not work, and the tile may have to be replaced. Generally, for dry, sunny climates, sealants are not recommended.

Slate is a natural, strong stone. Building a patio with slate is an investment – but slate will last for decades. Your pieces of slate have already been around for hundreds of thousands – even millions -of years. Using slate for a patio in your garden is a timeless, natural, organic choice. 

Summary: Do Slate Patio Slabs Scratch?

While slate slabs do scratch and mark, they are still a good choice for patios if you’re careful to buy high quality stone. Top standard slate looks completely stunning.

Select dense, non porous slate from the UK, Portugal, New York or Vermont – and their low levels of water absorption will mean you get a harder surface less prone to flaking and deep scratching. 

This in turn will mean any scratches you do get (and you will), can be dealt with more easily so your slate surface looks great for a longer time.

Mark H.

Homeowner and property investor Mark H. aspires to bring you the very best outdoor living content, based on his years of experience managing outside spaces. Read more >