Graphenstone Siena - Decorative Limewash Paint

The paints Graphenstone offer are some of the best you can buy in the UK, and we’re happy to have Graphenstone as one of our hero brands here at Greenshop Paints in Stroud, Gloucestershire

Lime interior paint, limewash effect. Part of The Earth Collection.

Siena is gorgeous lime based paint, and it dries to a matt finish. Soft, chalky, full of cloudy movement, it looks like the back room of a beautiful old farmhouse. I think it's one of the most characterful finishes we sell, and has been mega popular on the socials for a couple of years now, and still getting more interest daily, . Flat, even, modern colour is not what this does - gone are those days.

Proper old fashioned limewash can be powdery to the touch, and wiping a mark off is hopeless. Graphenstone build a bit of graphene into theirs, and once it's properly cured you can actually clean it. For a lime finish that's unusual, and it's the main reason I'd use Siena in a hallway or a child's room where ordinary limewash wouldn't be the next choice. 

Basically, all the character of an old limewash but to modern practical standards. 

Eco credentials

Cradle to Cradle Gold is a pretty good one. It grades the whole product, raw materials right through to whether the empty tub can go round again, rather than the single VOC figure everyone quotes. 

On air quality it's about as clean as paint gets. VOC content under 1 g/l, an A+ emissions rating, and trace VOCs under 0.1%. There's next to no smell in the room even while you're applying it. It also carries EUROFINS Indoor Air Comfort and a full Environmental Product Declaration, both independently verified.

Lime takes CO2 back out of the air as it sets. The wall pulls carbon in while it hardens, the same slow reaction that's held lime mortar together on old buildings for centuries.

Tubs are recycled polypropylene and recyclable again afterwards.

What's in it

Aerated lime with graphene reinforcement and bio binder.  Not much else. No acrylic binder, no vinyl, nothing plastic. Being a mineral paint, it bonds into the surface chemically instead of forming a skin on top, which is what lets it breathe and where the chalky depth comes from.

Wet, the paint is pH 13, so strongly alkaline. Gloves on, keep it out of your eyes, and don't breathe in the mist if you're spraying. Dry, none of that applies.

What to use it on

Interior walls and ceilings, on plaster, plasterboard, drywall, prefab boards or brick. New or already painted, it doesn't matter, as long as the surface is sound. New plaster needs 28 days to dry out before lime goes anywhere near it, and the same holds for any fresh mineral surface.

Prep depends on what you're starting with. Bare absorbent walls take a coat of Ambient Primer. Fresh plasterboard and filled repairs need spot-priming or a mist coat of Naturcolor first, or the patches drink the paint in and dry a different shade to the rest. Shiny or previously painted surfaces want a light sand to key them, and a primer wherever the old paint is slick.

Wood, metal and anything non-porous need Four2Four underneath. Lime has nothing to grab onto on those by itself.

Indoors only. Keep it off anything permanently sitting in water, the inside of a shower being the obvious one. Bathrooms and kitchens are fine with a couple of extra steps, which are in the questions below.

How to apply it

This goes on by hand, and the finish lives or dies on how you do it.

Thin with up to 5% water for a normal limewash. Stir it well but go gently, because over-shaking brings air in and the bubbles show up on the wall. 

Two coats, with a mitt, a sponge or a masonry brush. Loose rounded strokes, or criss-cross, and don't try to lay it on evenly. The patchiness is the point of the whole thing. Even it out too much and you've made standard matt emulsion.

Thin coats only. Lay lime on thick and it cracks as it dries and drags the curing out for ages.

Timings, at 25°C and 60% humidity: 2 to 4 hours between coats, 24 hours to dry. Colder or damper rooms stretch that out. Work between 7 and 35°C, out of direct sun, and don't start if the humidity's above 80%.

Lime is slow to show its colour. For the first 3 to 4 days the finish looks thin and blotchy as it carbonates.. Leave the wall alone and it fills in on its own. Full cure is about 30 days, and that's the point the Class 1 washability kicks in, so hold off cleaning it before then.

Brushes and mitts wash out in warm water.

It does a lovely faded whitewash on bare brick too. Damp the brick if it's dry, one coat on, let it go nearly dry for half an hour to an hour, then sponge it back while it's still soft until the brick shows through the way you want. Patch in anywhere that's gone too far.

Questions we get asked

Can I paint over my existing walls? Most of the time, yes, provided what's there now is firmly stuck down and not flaking. Lime needs to grip and it needs to breathe, so over standard matt emulsion in good condition give it a quick sand to key the surface and prime where needed. Over gloss or anything heavily plasticky, prime with Four2Four first. If the old paint is powdery or peeling, deal with that before you start or the lime comes away with it.

How much will I need? Around 5 to 6 square metres per litre over two coats. A 1 litre tin covers roughly 5 to 6 square metres, a 4 litre 20 to 24, a 12 litre 60 to 72. Thirsty walls and a generous hand will use more, so test on your own surface before ordering in quantity.

Do I have to buy the colour separately? The tin says that you need pigment, but we’re mixing all colours to spec when you order them, so you can use straight from the tin, 

Why's it patchy when I first put it on? It's lime, and lime is slow. The opacity builds over the first 3 to 4 days, so it nearly always looks thin and uneven at the start. People ruin it by adding coats too early. Give it those few days.

Can I use it in a bathroom or kitchen? Fine in both. I'd still want a decent extractor in a shower room, but the walls themselves cope. Keep water off it for the first 4 to 5 days while it cures.  The only no is anywhere in constant contact with water.

Is it washable? Yes, once it's fully cured at around 30 days. That's when it reaches Class 1, the top band. Before the 30 days are up, don't scrub it.

Will two coats cover a dark colour? Usually. Over a really dark or strong existing colour, lay a mist coat or a tinted basecoat first so you're not fighting it through two coats. A test patch answers it for you in no time. 

Is it safe around the family? Yes. Trace VOCs, A+ rated, barely any smell, so the room stays breathable while you work. The one thing to watch is the wet paint being alkaline, so gloves and eye protection on and keep it away from small children. Once dry it's completely inert.

Can I mix it with another paint? No. Don't blend it with other brands, it stops performing the way it should.

How do I store what's left? Reseal the tub and keep it cool and dry, out of the sun and away from frost, between 5 and 35°C. Unopened it's good for 24 months. If it thickens in the tub it hasn't gone off, just stir or shake it back.

Other info
Graphenstone Siena Limewash vs Bauwerk Limewash Paint