2023- an update…
Since writing this post back in 2014, it has become one of the most viewed articles on my site (probably because most online advice refers to slate floor tiles). I’ve tried and tested a number of slate/stone cleaning (and sealing) methods in those seven years.
I don’t use oil, WD-40 or slate sheen anymore (though still clean in very hot soapy water) and generally only use two products; Lithofin MN Power-Clean and Lithofin MN Stain-Stop. I don’t receive any royalties or discounts from Lithofin (this isn’t a sponsored article!), I’ve simply found through much experimentation that these two products work best for my needs (and those of my customers).
I use Lithofin MN Power-Clean mostly on reclaimed slates and slabs that may have stains, paint marks, rust etc. and it’s proven to be way more effective than hot soapy water or any solvents I’ve tried (e.g. acetone, methanol, iso-propyl alchohol).
Lithofin MN Stain-Stop is used on nearly all of my finished slate products- from house signs to wall hangings to cheeseboards/trivets. It protects exterior products from water ingress and oils for up to 5 years (after which, wash and re-apply). It’s also food-safe when dry (NB- it’s recommended not to ‘apply in rooms where lightly wrapped food is stored’). Finally, I’ve found that it enhances the natural colour, grain and wonderful inherent properties of slate.
The above is my own personal advice and experience BUT I take no responsibility for your slate and stone! Read and follow the Technical Advice for the products before you even open the containers.
Follow this link to the Lithofin site.
My original 2014 article (with a couple of corrections);
Cleaning Slate- I’m often asked how to clean slate, so here are a couple of my top tips;
– although slate is porous, it has a relatively low water absorption property (think the slate tiles on a roof). However, polished and older slate can absorb more liquids. Furthermore, slate will absorb oils and these can stain slate products and pieces used in the home. I have some Cornish sea slate pebbles that will extract moisture from hands as you hold them.
– the simplest way to clean slate is using very hot soapy water- this should remove most stains, especially from newer slate.
– for cheeseboards, an effective way of preventing stains is to rub the whole surface lightly with olive oil. Be aware though- this will not only darken the slate, but also the carvings- they may end up not quite so obvious on the surface.
– for wall plaques/exterior trivets (for non-food items), you can rub lightly with WD-40 or a proprietary slate sheen or oil. This really brings out the natural qualities in each slate piece (but again, may darken down some carvings).
– or just leave the slate to age and form a natural patina over the years (the trivets that I use in my kitchen are un-treated).
– you can even put slate in your dishwasher. BUT- I won’t be responsible for either the slate, or your dishwasher should you want to try this out. Use your own discretion.
HATCH BURN CARVE 