- Practical advice
- Warm up the room
- Preliminary steps
- A preparation in the rules of the art
- Subtle hues
- Decorative effects
- Prepare the wall
- Place the supply ducts
- Brush and moisten the wall
- Project gobetis
- Put in place the guide slats
- Apply the plaster
- Smooth the wall
- Control the flatness
- Remove the guide slats
- Recap and equalize the hollows
- Standardize the surface
- Harmonize corner stones
- Brush and clear the wall
- Lay the final layer
- Make the wash
- Apply with a brush
- Make the finishing patina
- Lengthen the preparation
- Complete with the pigment
- Apply touch-tinted wax
Covering the gable wall with a habitable roof, this plaster made of lime composes a Mediterranean decor where blue and ochres cohabit harmoniously. The final touch is provided by a tinted wax, applied hot.
All to do it
- Sand of grain size 0/4, 0/3, 0/2 or 0/1: 3,90 € approx. the bag of 40 kg, trades.
- Lime CL 90: from 11 to 13 € the bag of 35 kg (Balthazar and Cottes, Calcia, Chaubat...).
- Yellow and red ocher (earth decorations) and pigments compatible with lime: yellow and red cadmium, yellow and red of Mars, golden yellow (Liberon, Castorama): from 7 to 10 € the 250 g.
- natural beeswax: from 10 to 20 € per kilo. Essence of turpentine: 2,20 € approx. the l.
- Tools: concrete mixer, trough, trowels including cat-tongue, wooden floats of various sizes, mason rule, bubble level + 3 cleats of 10 x 20 m section.
- Overall cost: from 8 to 10 € the m2.
Warm up the room
In the category "natural deco", lime deserves the golden prize! Very economical, it is ideal for structural work as for finishing. In decoration, it displays its qualities, luminous and expressive. Its simplicity of implementation adapts to all types of interiors.
The coating presented allows towarm up the room, converted into a student room. Thanks to the aerial lime used in its composition, it offers a refection respectful of the existing masonry, limestone. Its application is traditionally carried out in three layers, supplemented with a whitewash weathered with beeswax.
- Cover the floor and remove the old friable chisel or flat chisel.
- Dig joints about 3 cm deep, fill in cracks and holes: to respect the existing one, it is advisable to use lime mortar and stones.
- Brush the masonry to remove residues. The railway is disadvised because it weakens the limestone blocks by attacking the cullet (protective gangue). In addition, he removes their beautiful patina.
- Once the wall is dusted, water it copiously the day before the work so that it becomes wet. Essential step to prevent the porous rock from pumping the water contained in the coating too quickly. It would follow a phenomenon of crazing (microcracks) and cracks would occur eventually. Effects in contradiction with the natural qualities of lime, its flexibility in particular, which allows it to withstand climatic variations well.
A preparation in the rules of the art
- Rewet the wall one to two hours before start-up.
- Thin and fluid, the first layer (the gobetis) is the link between support and plaster body, applied later. It consists of 1 volume of air lime CL 90 and 2 of sand (particle size 0/4) intimately mixed with water. It is possible to devote 10% of the volume of lime to the introduction of natural hydraulic lime (NHL 2 or 3.5), as did the old ones in order to make the coating more resistant. Thrown roughly with a trowel, the gobetis fills the joints and covers the stones to a thickness between 0.4 and 0.8 mm.
- The body of coating (or rough) is done "a fresco" (fresh on fee), which promotes a long enough drying. Composed of 1 volume of lime for 2.5 of sand (particle size 0/3), it is tempered to form a soft paste which is applied in thick layer (from 10 to 20 mm). This makes it possible to waterproof the wall, correcting the inequalities.
- After attaching guide slats, the mixture is thrown by trowel, then pulled to the ruler and smoothed.
- The topcoat is here implemented on the coating body still fresh. Quite thin, it is richer in sand (3 vol) than in binder (1 vol of lime). Its application is by trowelling or troweling, "tightening", to a thickness of 0.2 to 0.5 mm. The final appearance, more or less granular, depends on the fineness of the sand (particle size 0/1 to 0/2) and the tool used. We have chosen a rather rough, but raw, but many other processes are possible: brushed finish for a rough and homogeneous appearance, scraped with a special comb, smoothed with the trowel covered with felt, speckled with zip line, etc.
- The whitewash is perfectly adapted to this support. Composed mainly of aerated lime, dye and water, it is simple to manufacture and, again, very cheap. Its measure: 1 volume of lime for 3 of water. With 10 liters of mixture, we cover 15 m2 about, in three layers.
- Pour the lime into the water in rain, then knead using an electric mixer or a perforated cleat. There should be no lumps.
- Staining requires products that are compatible with the characteristics of lime. The ochres and the grounds provide watercolors (declination of yellow, orange, beige and brown...). It is also possible to play with more intense colors, based on metal oxides. To be used with moderation however (not more than 2% of the weight of the dry binder) because they have a strong chromatic power.
- Here, the coloring is done with ochres, at a rate of 15 to 25% of the mixture. They are diluted with very hot water, with a few drops of dishwashing liquid.
- To fix the color and ensure its longevity, add to the preparation, by bucket, a handful of salt alum (found in pharmacy) or two coarse salt. The addition of an adjuvant plug (Sikalatex...) softens everything and promotes adhesion to the substrate.
- The application is carried out in three stages with a wallpaper brush (or a large spalter) so as to cover the coating by emphasizing its asperities. After the first pass and 24 hours of drying, gauge the color. The second and possibly the third pass can be more or less sustained.
- Wax is commonly used to skate and give personality. It can be made yourself with natural beeswax (in drugstores or beekeepers). To be prepared in a bain-marie so that the flame is never in contact with the preparation, volatile and highly flammable.
- Melt 500 g of beeswax in 75 cl of turpentine until completely dissolved. To extend again with 75 cl of turpentine and to pour, filtering, in a glass pot. The pigmentation (in small quantities) takes place just before the total cooling, and it can change. Make tests in an inconspicuous place, knowing that on a small surface, the effects produced are often accentuated.
- Apply the preparation hot, after complete drying of the coating. Two weeks are required on average.
- Divide the pot of wax in boiling water, to liquefy it. Spread it in circular motions with a scrub brush. The structure of the plaster, smooth or rough in places, produces the watercolor effects. Leave as is for a matte effect, or polish with a woolen cloth (lint-free) after one hour of drying.
Prepare the wall
The wall to decorate, limestone, is in good condition and already almost bare. Remnants of friable plaster are removed, large holes filled with salvage blocks sealed with lime mortar.
Place the supply ducts
We take the opportunity to embed the power supply ducts. For this, it is sometimes necessary to rework the stones in order to pass the pipes without damaging them.
Brush and moisten the wall
Brush the wall from top to bottom to prevent waste from redeposing on the treated parts. The day before the work, water it copiously using a sprayer (without flooding the room!).
Rewet one to two hours before applying gobetis. Then prepare the mixture and trowel it in a thin layer, which must fill the gaps and adhere to the masonry at all points.
Put in place the guide slats
In the still fresh gobetis, embed the guide slats spacing them by about one meter. Be sure to adjust them level with each other and with the wall, and keep them on the ground on a bed of mortar.
Apply the plaster
Mix the plaster body until a soft paste is obtained. Place small amounts on a trowel and bring it close to the wall to trowel the mixture from bottom to top. Work from one end of the wall to the other, packing as needed to consolidate the outfit.
Smooth the wall
Using a mason's ruler, smooth the surface, always from the bottom up, by printing oscillating movements.
Control the flatness
Check flatness as you go. Bridging the gaps and smoothing the rule again. In the process, to make the surface uniform, pass a wooden trowel.
Remove the guide slats
Wait a few hours for the coating to set before carefully removing the guide slats. Use a trowel to keep the mortar adhering to the wood, and pack well.
Recap and equalize the hollows
After rewetting the voids and surrounding areas, cover with a mortar of the same consistency. Tighten with a trowel, slightly exceeding the level of the already floated surface.
Standardize the surface
Finally, carefully float the fittings to make them invisible. If necessary, rewet the entire wall in order to raise the rinds of lime and, thus, standardize it.
Harmonize corner stones
The corner stones, at the entrance to the room, are highlighted. With a cat's tongue, the mortar is inserted into the joints and then smoothed, being careful to end with a slight roundness.
Brush and clear the wall
The finish is paramount. To leave no demarcation, brush the joints stones / plaster as soon as the grip is made. The roundings are reworked to clear the blocks to the maximum.
Lay the final layer
Apply the final layer with a trowel, about 0.5 mm thick. Wait half an hour and then float, moistening if necessary the tool, to raise the surface water by capillarity.
Make the wash
For the whitewash, pour 1 part of lime for 3 volumes of water. Dilute the dye with boiling water and a few drops of washing up liquid. Add the adjuvant, a handful of alum salt, and mix.
Apply with a brush
A wallpaper brush is ideal for applying whitewash. The first layer, passed fresco in all directions, allows the pigments to well impregnate the coating by creating watercolor effects.
Make the finishing patina
Place 500 g of wax in a glass container and 75 cl of turpentine. Heat everything in a bain-marie, without contact with water, and let it melt.
Lengthen the preparation
At the end of the heat, lengthen the melted wax by pouring another 75 cl of turpentine. Tip: Wrap the top of the container with a tights to filter out impurities.
Complete with the pigment
Before complete cooling, add the coloring powder at the rate of one teaspoon to 250 g of wax until you get a raspberry pink pretty bright. Mix well because the pigment sediments.
Apply touch-tinted wax
Heat the wax in a bain-marie and apply with a quack brush. As it gels on contact with the cold wall, it is necessary to work in rapid circular motions to penetrate the coating.