Lime plaster has been used for centuries as a durable and eco-friendly wall finish. Its natural composition allows for breathability, moisture regulation, and a unique aesthetic that modern materials struggle to replicate. Whether restoring an old home or adding a rustic touch to a modern space, learning to mix and apply authentic lime plaster is a rewarding DIY project. This guide will walk you through the process step by step.
What is Lime Plaster?
Lime plaster is a traditional wall finish made from slaked lime (calcium hydroxide), sand, and water. When exposed to air, the lime reacts 漆喰DIY with carbon dioxide and gradually hardens into calcium carbonate, creating a strong and long-lasting surface. Unlike modern cement-based plasters, lime plaster is more flexible, making it less prone to cracking.
Materials and Tools You’ll Need
Before you begin, gather the following materials and tools:
Materials:
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Hydrated lime (also called slaked lime)
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Fine sand (washed and sieved)
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Water
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Natural fibers (such as horsehair, if desired, for extra strength)
Tools:
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Mixing bucket
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Trowel or hawk and float
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Paintbrush (for misting the surface)
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Sponge or damp cloth
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Protective gloves and goggles
Step 1: Preparing the Surface
For lime plaster to adhere properly, the surface must be porous and free from dust, grease, or paint. If working on drywall or modern cement, apply a rough base coat or a bonding agent to create the right texture.
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If plastering over brick or stone, dampen the surface slightly to prevent it from sucking moisture from the plaster too quickly.
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If working on wood lath, ensure that the lath is securely fastened and spaced for proper adhesion.
Step 2: Mixing the Lime Plaster
Proper mixing is crucial for achieving a smooth and workable plaster.
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In a large bucket, mix 1 part hydrated lime with 3 parts sand.
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Slowly add water while stirring until the mixture reaches the consistency of thick yogurt.
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Let the mix rest for at least 24 hours to allow for full hydration.
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Before applying, remix the plaster to ensure an even texture.
Step 3: Applying the Base Coat
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Apply the first layer (also known as the scratch coat) using a trowel. Spread the plaster evenly to a thickness of about 1/4 inch.
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Use a notched trowel or stiff brush to create a rough texture. This helps the next coat adhere properly.
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Let the coat dry for 24–48 hours, misting it occasionally to prevent rapid drying and cracking.
Step 4: Adding the Finish Coats
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Once the base coat is dry, apply a second layer (the brown coat) with the same technique but smoother.
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Let it dry for another 24–48 hours, again misting occasionally.
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For a polished look, apply a final thin finishing coat and smooth it with a damp sponge or trowel.
Step 5: Curing and Sealing
Lime plaster requires slow curing. Keep the plaster moist for about a week by lightly misting it daily. This ensures a strong and durable finish. Once fully cured, you can leave it as is for a natural look or seal it with a natural wax or limewash for extra protection.
By following these steps, you can achieve a stunning and authentic lime plaster finish that enhances the beauty and longevity of your walls. Happy plastering!