Deco&Design - DIY Finishing - Finishing Techniques

Natural lime-based plasters and paints ideal for bedrooms and children's rooms

Lime is a material with a lot of qualities, unfairly forgotten. Although there was a time when no one could conceive of general cleanliness without lime, it is now being replaced by other materials and few would think of the lime option if they had to paint. Even more so if they were to finish the wood. And yet such primers and paints are still used for walls, ceilings or floors to achieve a healthy environment, very suitable for children, people with allergies or respiratory conditions. Let's take a closer look at lime.

Once upon a time...

There was once a village in the Bărăgan where in spring all the houses were shaken, swept and painted, inside and out, to be clean, tidy and smell nice for Easter. Where the trees were cleaned of the dryness, the trunks were varnished up to 1 m from the ground, and the dryness from the trees and the garden was gathered in the middle of the garden where a big, purifying fire was made. And it smelled beautiful, spring-like and clean!

Fortunately there was not just one village in the Bărăgan but many villages here and elsewhere. Unfortunately, I don't know how many of these villages still do such activities and how many still enjoy the smell of freshness and cleanliness that freshly painted walls give off.

Our elders knew, without chemistry or biology lessons, that lime is a natural antiseptic, that fungus and mould don't grow on painted walls, and that those in the house are less likely to get "chest" (respiratory problems). They also knew that the varnished trees would not be attacked by insects. But it began to bother us that the lime on the wall sometimes got on clothes, that it was harder to work with, and we invented new products, easier to use, more resistant, but not always as healthy. Lime slowly got out of our idea of cleanliness and we forgot how many qualities it has. I think it's not too late to remind ourselves of the qualities of lime and as far as possible, start using it again.

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somewhere in the Bărăgan
What is lime and how to use it

Lime can be considered the most versatile building material of the civilized world. The Egyptians, Mayans, Greeks and Romans used it as a binder in mortars, plasters and paints, and the buildings have stood the test of time. Although it was originally used more as a mixing material, since the middle of the last millennium (1500s) it has also been used for interior and exterior wall finishes. It was used by Leonardo da Vinci, Michelangelo and Raphael, and is mentioned to have been used for works of the time.

Heavy use continued until after the Second World War, when it was overshadowed by the advent of cement, a harder material that hardened much faster than lime. But now lime is making a comeback because of its properties.

The wall lime, after drying, is the same as the natural rock from which the finishing material - calcium carbonate CaCO3 - is made. The process of obtaining and using lime is comparable to a hoop. Calcium carbonate is a natural rock formed millions of years ago from the shells of sea creatures. It is also called limestone. In order to be used, it is burned at temperatures of 800ºC and converted into calcium oxide CaO - unbound lime, a substance that is unstable in the presence of water.

In reaction with water the un slaked lime "quenches", turning into calcium hydroxide Ca(OH)2 - slaked lime. The reaction is very violent, with a strong release of heat, and the process can be quite dangerous if the lime slaker is inexperienced. Slaked lime is used for plastering and to make lime milk, which is applied as a final finishing coat. Once applied, the lime (calcium hydroxide) slowly reacts with the carbon dioxide in the air and returns to its original form of calcium carbonate CaCO3, the hard solid layer that remains on the wall. And so the circle closes. Lime is considered a natural zero-carbon dioxide material precisely because what is released during its production is consumed during curing (drying).

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Benefits of using lime when finishing the walls of the house

In addition tozero carbon dioxide balance, lime also has other advantages. Has alkaline pHwhich prevents fungi and mould from growing, making the air in the painted rooms very healthy. It is recommended for wall coverings in children's rooms, people with respiratory problems or allergies.

The walls are painted to allow water vapour to pass through acting as a permeable barrier. This prevents moisture from being trapped inside the wall, which prevents damage to the building (masonry or structural timber).

Mix well with clay, gypsum and cement being a very good binder for these materials.

It is white with a slight natural glow. Thanks to this bright colour it gives the feeling of cleanliness. But it can be mixed with pigments to be coloured if you want walls other than white.

Last but not least, lime does not burn. It is a flame retardant material protecting the substrate on which it is deposited.

The weak point is that the lime shrinks when drying and cracks can appear. This is why it should be applied in a thin layer and the next layer applied only after the previous one has dried completely. This leads to a longer working time compared to other materials.

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Modern natural products with the same qualities but without application or cracking problems

The use of natural products in building and finishing homes is a growing trend lately. Lime is also being targeted, but its use no longer involves extinguishing it as it used to. Lime is ready to use - like modern paints - or in powder form that is mixed with a well-determined amount of water to make a strong, healthy plaster.

Naturalpaint is one of the companies that aims to return to healthy natural products. In addition to natural insulation for wooden and brick houses or waxes and natural oils for wood, lime has also made its way into the company's portfolio. Whether it's in the form of plaster, render or paint, lime retains all the qualities of the lime used in the past, adding new ones through the manufacturing process. For example, the addition of cellulose - a natural binder - makes the plaster much better fixed and no longer easily catches on clothes when we lean against the wall.

The antiseptic properties of lime products from Naturalpaint are also confirmed by Oko-test magazine in Germany, which focuses on environmental friendliness. This magazine tests products on the market and gives them marks. In the case of lime-based paint the rating was Sehr Gut (very good).

So there is the possibility of going back to lime without the work and risks that this has entailed in the past.

How lime looks on wood. Limewash finish

Also from the past comes the limewash finish for wood. When they varnished, grandparents didn't limit themselves to clay walls, but also covered the ceiling or the parquet floors made of glazed boards. Sometimes even the furniture. Lime protected the wood from insect attack, they knew this from the trees in the garden. Over time, the lime would melt and the wood would begin to show underneath. This is what the finish looked like limewash.

Some consider it to be identical to whitewashothers see it differently. From my point of view it is different, whitewash being the softer, less rustic, more elegant version. Limewash retains the roughness of lime with a less elaborate, more raw look.

The look can be achieved using lime paints or other materials that are not very fine-grained. After applying the material and processing to achieve the desired effect, the finish is fixed with transparent wax. In this way it will also be protected and easier to maintain.

White wax can also be used to reproduce the limewash effect. The content of white pigment or calcium carbonate in the wax must be high for a very good coverage. It is a very good material for marking large pores in wood. For a good result apply in excess, then wipe off the excess with a cloth.

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The cousin is a material whose return to our lives has only beneficial effects. Used to paint walls, it protects them from fungi and mould, lets them 'breathe' by allowing moisture to pass through and restoring balance, improves the air in the room, making it easier to breathe for those with respiratory problems or allergies. And the wood is protected from insects with the "price" of a very interesting finish - limewash.

Thinking of painting and not decided on wall paints? Varnish may be the solution!

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About the author

Mihaela Radu

Mihaela Radu is a chemical engineer but has a great passion for wood. She has been working in the field for more than 20 years, wood finishing being what defined her during this period. She gained experience working in a research institute, in her own company, as well as in a multinational. She wants to continuously share her experience with those who have the same passion - and more.


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