Brick

Limewash vs Painted Brick

Apr 2, 2021 Justin Richardson

Limewash is not paint, and the difference matters more on brick than anywhere else. Brick is porous and needs to breathe. Paint it and you trap moisture between the surface and the brick — which gives you mold, peeling, and brick that can never be restored. Limewash lets the moisture through, which is why it has been used for centuries and why it is the safe option.

Using Limewashing to Stain Brick Header Image 2 1

Limewashed brick.

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A note on products: limewash is made from high-calcium hydrated lime and water — a general building material Direct Colors does not stock. What we do supply is the concrete pigment that tints it, which is what frees you from plain white.

Why not just paint it

Because brick needs to breathe. Painted brick traps moisture behind the film, and the result is mold, peeling paint, and brick that cannot be reused or restored afterwards. That is a permanent decision made with a temporary product.

paint on brick wall chips and peels

Paint on a brick wall, chipping and peeling.

Getting the lime right — the one thing people get wrong

You need high-calcium hydrated lime: At least 95% calcium content
In the US that is usually designated Type N
Avoid Type S: More magnesium than calcium — wrong for this
Avoid anything classified agricultural
Use hydrated, not quicklime: Slaking quicklime yourself generates a lot of heat and a very caustic solution. Hydrated lime skips that hazard entirely

Protect yourself properly. Limewash damages skin, eyes and other tissue. Goggles or a full face shield, long sleeves and trousers, gloves — and a dust mask while mixing, because the lime is extremely fine and you must not breathe it.

Mixing

Lime putty: Buy it pre-mixed, or make it at one part lime to five parts water
The limewash: One part putty to four parts water
The awkward bit: Lime is measured by weight and water by volume. Use 8.33 lb as the weight of a gallon of water and you can do the conversion
Easier in metric: A liter of water weighs a kilogram, so the ratios work out directly
For more opacity in fewer coats: Add Portland cement to the limewash
For color: Add concrete pigment — this is what gets you off white

Jackie's black limewashed wall

Jackie P. had a brick wall to limewash and did not want white, so she pigmented it black instead. Three coats took her about six weeks — and her practical notes are the most useful part of this article.

Her batch: 24 lb water · 4.8 lb lime · then iron oxide pigment, mixed in a 5-gallon bucket
Coats: At least three — hers took about six weeks
Brush: Natural bristle, inexpensive 3-inch wooden handle
Kit: A good scale, and several pairs of rubber dishwashing gloves

“Lime-wash is a multi-coat process with at least three coats. So, to cover all the bricks three times has taken me about six weeks to complete… The nice thing about multiple coats means you can try different amounts of color to know what you want the final coat to be.”
“It's a very messy project. It splashes everywhere and drips on everything. If you need to be careful you will want to put up tape and put down drop cloths.”
“It's helpful to have a broom to knock down spiders, their webs, and other insects from the bricks before you wet them.”
“Lime-wash is a great way to update the outside of your house with something that is safe and lets the brick breathe.”
— Jackie P.

Revitalizing an old red brick exterior with a fresh coat of gray limewash for a timeless look.

Weather matters

Never in hot direct sun: It dries too fast to work
Not too cold, not wet
Nothing in the forecast: Do not start if rain is due within three days
Ideal: Mild, dry, overcast — Jackie's words: “It really does help if it's an overcast day and not hot”
Brush, do not spray: You can spray it, but a brush gives a better result

Limewash or stain?

They do genuinely different things, and neither is simply better.

Limewash: Traditional, natural, breathable. Creates a chalky finish that changes the texture. Tintable with pigment. Less durable — expect to reapply periodically
Stain: More opaque, more consistent, and it does not change the texture. More durable. The right choice if you want an even color or want to keep the brick's surface as it is