With two or more coats (like we did), you get an opaque finish that won’t readily weather. You remember – the ones that looked like they got caught in the middle of a three-way gorilla fight. By doing so, they’re trying to replicate how a single coat of limewash would naturally distress over time, but to my eye, when done indiscriminately, it can look just as awful as those overly-distressed “shabby chic” pieces of furniture that polluted everyone’s social media feeds last decade. Most people tend to favor a distressed look achieved by applying one coat of limewash paint and then selectively removing areas of limewash with a garden hose. Limewash paint can yield a slight translucent whitewash look all the way up to completely opaque coverage. All commercially available limewashes contain aged slaked lime! I’ve read some articles by other DIYers claiming this brand or that brand “ages the slaked lime to perfection” like it’s some sort of fine wine or cheese. This aging period improves its binding properties, and this is what plain old calcium carbonate lacks. The calcium hydroxide remains stored in water for up to two years. The result of the slaking process is the conversion of the CaO (calcium oxide) into Ca(OH) 2 (calcium hydroxide). But with a little more water added, a more optimal lower temperature results – perfect for slaking. With the right amount of water, quicklime will almost instantly reach 300 degrees Fahrenheit. This is a massively exothermic process, meaning it gives off heat. To get a step closer to limewash paint, water is added to the quicklime in a process called slaking. Okay, we’re almost there, so stay with me! Slaking What those goons and despots got wrong was that quicklime is actually a preservative – it didn’t help decomposition one bit! But it did help control the odor, so after they filled in the graves, they wrongly assumed they’d destroyed the evidence of their wrongdoing. This resulting calcium oxide, known as quicklime, is a highly caustic and alkaline substance.īack in the crummy old days of unhinged tyrants, mass graves and gangsters who loved nothing more than to “moider da rat bastid,” quicklime was often sprinkled over the recently deceased to speed decomposition and help the bad guys get away with their crimes. Calcinationįirst, the calcium carbonate needs to undergo a calcination reaction, or put simply, you gotta cook the crap outta the rock at about 1300 degrees Fahrenheit until it decomposes into calcium oxide (CaO) and carbon dioxide (CO 2). Limestone is primarily calcium carbonate (CaCO 3) – the very same ingredient we use for our beloved DIY Chalk Paint Recipe.Ĭalcium carbonate, while helpful in making chalk paint and about a thousand other things, is not enough to make limewash paint. Despite the marketing efforts of certain brands, limestone is nothing exotic, and the limestone from this mountain range is no better than the limestone from that mounting range. Okay, let’s dig a little deeper, because science is cool and knowledge rules! How is Limewash made? Limewash has been used for millennia – largely unchanged for most of that time because at its core, it requires only two ingredients: hydrated (slaked) lime and water. This alkalinity makes it an inhospitable environment for bugs and other pests. On top of that, lime is naturally alkaline, with a pH around 12. As a bonus, the calcified coating of lime further acts to preserve the brick and extend its useful life. Limewash paint, as noted above, allows air and water to flow in and out of the brick unimpeded, just as nature intended. Trapped moisture weakens the brick over time, and the freeze/thaw cycle hastens deterioration in cold climates. If this sounds a bit murderous to you, well, it is!īy suffocating the brick, you quicken its demise. Modern paint suffocates the brick, as the latex (or other) film forms a barrier that interrupts its natural breathing cycle. This is the natural way of brick, and it needs to take place for the brick to retain its integrity. It draws water in when it rains and then allows that water to evaporate out. But lest I get too broad in scope, I’m just going to focus on brick houses.īrick, as a construction material or a non-structural cladding, breathes. Before I answer this, I’d like to mention that limewash paint has benefits far beyond brick and masonry, both inside the house and out.
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