Smooth application, stunning results

How to Prepare Surfaces for Lime Paint Application: A Complete Guide

          Lime painting is a popular choice for both exterior and interior surfaces due to its natural aesthetic, breathability, and durability. However, to achieve the best possible result, it's essential to prepare the surface properly before applying the paint. In this blog post, we’ll guide you through the step-by-step process of preparing different surfaces for lime paint, considering the material and condition of the surface.

          As with any similar project, always ensure that the surface is stable and not too wet. Lime paint, thanks to its natural and breathable properties, can tolerate slight moisture on the surface. The surface must be cleaned of any dirt, loose areas should be removed until a solid base is reached, and peeling paint or plaster must be scraped off. If necessary, the surface should be repaired. Old paint should always be sanded as much as possible, and the dust from sanding should be cleaned up.

1. Surface Preparation Without Priming: Fresh Mineral Materials Only

          To better understand whether or not priming is necessary before painting, and which primer to use, it's important to know why primers are used in construction projects in the first place.

          The main functions of primer are:

• Improving adhesion – useful when the surface is very smooth (e.g., smooth concrete, glass, tiled surfaces).
• Balancing moisture absorption – necessary when the surface has different materials (e.g., plasterboard with filled seams or old plaster patched with new plaster).
• Strengthening the surface – for old, crumbling plaster (in such cases, remove the plaster where it easily separates or is not in contact with the base wall, and then prime the remaining surface before continuing with the work).

          If your surface has been recently made with lime or lime/cement materials, priming is not necessary. This applies to both interior and exterior surfaces. It's important to understand what is meant by "recently made." In this context, it means the surface was created within the last month and has not yet been affected by external factors such as weather, dirt, or chemical reactions. To paint without prior priming, it's crucial that the entire surface has been prepared with a single type of mineral material to avoid areas with varying moisture absorption levels.

When Priming is Not Necessary:

• New constructions: If you’re building from scratch and using lime or other mineral-based plaster, you don’t need to prime before applying lime paint. This doesn’t apply to cases where the mineral surface is very smooth concrete.
• Major renovations: If a major renovation is being done and all walls or ceilings are being completely renewed with mineral materials, you can start painting with lime paint right away.

Remember, if you're unsure whether the surface is suitable for painting without priming, it's always better to prime first.

2. Priming for Cosmetic Renovations

          If the surface was previously painted with lime, lime/cement, silicate, or other mineral paints but not recently created (older than a month), priming will be necessary. In such cases, use KULTA Base Coat or a similar primer that is not based on acrylic or other polymers and does not form a film on the surface. This applies to situations where cosmetic renovations are being made without completely renewing the walls or ceilings or removing and reapplying new plaster. If you're unsure whether the surface was previously painted (or filled) with mineral materials (lime, lime/cement, silicate), it's best to remove the old paint (and filler) as much as possible by sanding to expose the mineral surface (lime, lime/cement plaster).

3. Non-Mineral Surfaces: Plasterboard, Silicone, and Acrylic Paints or Fillers

          KULTA is committed to natural and sustainable materials, focusing on mineral and natural surfaces. However, we understand that, for various reasons, it's not always possible to completely remove existing plasterboard structures or surfaces that have been filled and painted with polymers, and replace them with mineral materials. Therefore, we've developed a surface preparation method that allows you to paint with KULTA products and make your environment more natural.

          If the surface isn’t fully mineral-based, for example, if it’s painted with silicone or acrylic paints, or if it's a plasterboard wall filled with gypsum and acrylic or other polymer materials, a slightly different preparation process is required. In such cases, use an acrylic primer with quartz sand.

Acrylic Primer with Quartz Sand:

          This type of primer, often called "putzgrund," improves the adhesion of lime paint to both mineral and non-mineral surfaces. Some popular manufacturers offering such primers include Knauf, Weber, Sakret, Caparol, and Baumit.

After applying this primer, there are two options depending on the surface condition:

• Unstable surface with risk of cracking: If the surface is unstable with a risk of cracking or other defects, it can be reinforced with a mineral-based (preferably lime/cement-based) reinforcement mortar or plaster, where mesh can be embedded. This process involves embedding a fiberglass mesh into the mortar to provide stability, impact resistance, and long-lasting durability. This type of surface preparation is ideal for plasterboard surfaces, making the structure impact-resistant, more stable, long-lasting, and crack-resistant, while also giving walls a more natural feel. In this case, before applying this plaster layer, the entire surface should be primed with acrylic/quartz sand primer. After applying the plaster and before painting with KULTA, no further priming is necessary.
• Stable and even surface: If the surface is stable, smooth, and even with no cracks, then after the acrylic primer has dried, you can start applying lime paint right away. This method of painting is simpler and quicker, making it a good choice when you want to do a small cosmetic renovation without investing heavily in reconstruction, but still desire a more natural and aesthetic environment with KULTA paint.

Product Recommendations for Surface Preparation

          Here are some recommended products to help you prepare surfaces for lime paint application:

• Acrylic primer with quartz sand:
  • Knauf Putzgrund: Ensures good adhesion to both mineral and non-mineral surfaces.
  • SAKRET PG: With adhesion-enhancing additives.
  • Caparol Putzgrund 610: Widely used primer suitable for various surfaces.

• Mineral-based reinforcement mortar:
  • Baumit StarContact White: Ideal for reinforcement and leveling.
  • Knauf Multi-Finish: A versatile mortar that can be used for reinforcement and surface leveling.
  • SAKRET KAM: For leveling wall and ceiling surfaces, creating a finish layer before painting.

          Applying lime paint is a fantastic way to give your walls and ceilings a natural and long-lasting appearance, making proper surface preparation essential. Remember that the type and condition of the surface determine the necessary steps:

• If the surface is recently created with mineral materials, you can start painting as soon as the surface has hardened.
• If the surface is not recently created or is made from different mineral materials, patch-repaired, then priming with KULTA Base Coat is necessary.
• If the surface isn’t mineral-based and is unstable and fragile, like plasterboard, then priming with acrylic primer and possibly applying a plaster layer is required.

          By choosing the right products and carefully following the steps, you’ll achieve a high-quality result that will last for years.