LAYING AND GROUTING MOSAICS

Transcription

1 SEPTEMBER/OCTOBER LAYING AND GROUTING MOSAICS C O NTENTS: Introduction 1 Checking the substrates 2 Installation 3 Product classes according to UNI EN Grouting 5 In this issue of Focus on we would like to provide adequate information regarding the methods to be used for laying and grouting mosaics. Indeed, over the last few years mosaics have been increasingly applied in many design situations in both private and public sectors such as bathrooms, saunas and steam baths, swimming pools, bathtubs, kitchens or even as inserts in tiled walls. The large request for this type of materials has stimulated a number of companies to create mosaics made with alternative and innovative materials compared to traditional mosaics made with glass, ceramic or natural stone. So different types of mosaics have appeared on the market, made of wood, metal, resins, often in formats that differ from the usual square tile. In relation to this evolution today architects, designers and private clients can find endless furnishing solutions that stand out for their colours, shapes and materials. In order to guarantee an aesthetic and efficient result, it is necessary to follow some laying requirements and choose the more appropriate adhesives and grouting mortars according to the target environments, the type of mosaic and expected stress levels. The purpose of this article is to provide the correct information to achieve an optimal result. Mosaic wall spacers Profiles for mosaics 6 7

2 2 Checking the substrates Regardless of the type of mosaic chosen for the installation, the substrates need to have the following requirements: Flat: especially for laying glass mosaics, characterized by a limited thickness of about 3 mm, is essential that the substrate is perfectly flat and does not present any depressions. Small irregularities can be corrected using the glue itself as a levelling layer, while major irregularities (> 5 mm) must be removed by using suitable cement levelling layers such as Litoplan Rapid. FOCUS ON to check the level of residual humidity of the substrate with a carbide hygrometer or a conductivity hygrometer. Usually a cementbased substrate allows for a maximum humidity content of no more than 3-4%. For gypsum-based plaster this needs to be less than 1% and in the case of floorings made with auto-levelling anhydrite it must not exceed 0.5%. Clean: all substrates must be clean, free from dust and any substance or deposit that may affect the adhesion of the glue. Mature: for cement-based or gypsum-based substrates, an adequate maturing time must pass before installation in order to avoid the creation of humidity shrinkage cracks after installation, which may affect the final outcome of the work. Resistant: in order to ensure a good degree of adhesion the substrates must be strong enough and with a non-powdery surface. To improve this feature appropriate consolidating primers can be used, like PRIMER C, which is compatible with any cement-based adhesive. Dry: before installation, it is always advisable PRIMER C Consolidating and insulating primer in aqueous dispersion for indoor use. LITOPLAN RAPID Thixotropic cement-based levelling layer with ultrarapid drying and hardening for vertical and horizontal applications from 1 to 25 mm thicknesses.

3 3 INSTALLATION For mosaics glued on net or paper sheets with the classic format of approximately 30x30 cm, before proceeding with the laying, it is advisable to draw on the surface to be coated lines that help to put the sheets properly. After lying them on the floor, measure the total size of 3 sheets, placed in such a way that the distance between the sheets is equal to the distance that between the tiles; report this measurement on the surface to be coated, both horizontally and vertically, in order to trace a grid using the straight edge and the level. The wall will be divided into several squares, each of which corresponds to nine sheets of mosaic. If the mosaic represents a drawing or has to follow a particular direction follow the laying instructions indicated by the manufacturer. Even in case of mosaics with tiles that do not have a square shape and therefore with irregular edges on the sheet, it is important to FOCUS ON make sure that the distance between one sheet and the other is equal to that between the individual tiles, so that all the joints are identical. Let's now turn to the choice of the adhesive, which, as already mentioned, must be made by taking into account the type of mosaic to be installed, the nature of the substrate and the intended operating conditions. You should generally prefer white adhesives with no vertical slip in order to prevent the sheets from sliding when installed on a wall and achieve a perfect alignment. White adhesive should be preferred for clear glass mosaics in order to avoid unwanted shades of colour on the finished surface. Shown in Table 1 below is a list of the adhesives offered by Litokol according to the different types of substrates. SUBSTRATES Litoplus K55 Litoplus K % Latexkol diluted 1:1 with water Litochrom Starlike Litoelastic Cement-based substrates Gypsum-based substrates (*) Primerized with Primer C * * Gypsum-boards Wooden or metal substrates Swimming pools and bathtubs waterproofed with Elastocem and Coverflex Internal moist areas waterproofed with Hidroflex Substrates consisting of old ceramic tiles Lightweight panels Tab. 1: chart to choose the adhesive.

4 4 Product classes according to UNI EN LITOPLUS K55 (C2TE) Completely white high-performance (C2) cement-based adhesive with no vertical slip (T) and extended setting time (E). A special mention must be given to the LITOCHROM STARLIKE epoxy mortar, which can be used both as an adhesive and as a grouting mortar. There are several benefits associated with this product, namely in the case of very thin glass mosaics there is the possibility of using the same product both as glue and filler. It allows to use any colour without the risk of interferences between the grouting colour and the adhesive used for installation. LITOPLUS K % LATEXKOL diluted 1:1 with water (C2TE-S1) Completely white high-performance (C2) cement-based adhesive with no vertical slip (T) and extended setting time (E), deformable (S1). LITOELASTIC (R2T) Completely white (R2) improved reactive adhesive with no vertical slip (T). LITOCHROM STARLIKE (R2T) Improved reactive adhesive (R2) with no vertical slip (T). Compliant with RG class according to UNI EN reactive grouting mortar. As shown in the table it is a very versatile product and can be used on a variety of substrates both indoors and outdoors. Once you have selected the most suitable adhesive and prepared the mixture as indicated on the packaging and on the data sheets, we recommend applying the adhesive mortar on the substrate with the smooth side of the spatula in order to make the colour of the substrate even and immediately after apply an additional amount of product using the 3.5 mm notched spatula. It is preferable not to cover areas that are too wide with the adhesive in order to prevent the formation of a film on the surface. For particularly thin mosaics (<3 mm) a spatula with a thinner notches can be used (see photo). Apply the mosaic sheets by tapping the tiles with a rubber spatula to ensure a perfect adhesion, preventing the adhesive from leaking into the joints between the tiles and leaving enough thickness for the subsequent grouting. If a paper-mounted mosaic has been applied, the paper must be removed after approximately 24 hours or anyway when the adhesive is completely set. The paper, moistened with a sponge, can be easily removed after a few minutes by slowly pulling it diagonally and close to the wall. At this stage we recommend removing the surface of the mosaic completely by washing away with clean water any residue of the paper adhesive that may interfere with the subsequent grouting.

5 5 GROUTING Before starting to grout the joints, it is necessary to ensure that the adhesive used previously is completely dry and hardened. After checking this, mechanically remove from the joints any adhesive that may have leaked into them. The grouting can be carried out either with coloured cement-based mortar like LITOCHROM 1-6 or with epoxy mortar like LITOCHROM STARLIKE that guarantees a perfectly even colour and total non-absorbency. For a correct application follow the directions reported on the packaging and the data sheets. LITOCHROM 1-6 High-performance cement-based sealant for grouting 1 to 6mm joints. Compliant with class CG2 according to UNI EN Epoxy mortar with two anti-acid components for laying and grouting ceramic tiles and mosaics with joint widths from 1 to 15mm. Patented product b1. Compliant with RG class according to UNI EN SPECIAL CASES In this section we list some warnings to watch out for in the case of special mosaics or when the installation is more critical in terms of application. Natural stone mosaics For this type of material, consisting of many morphological variants, it is necessary to carefully choose the most suitable grouting mortar. For instance, apart from having to be glued with white cement-based adhesives (LITOPLUS K55), white crystalline marbles can not be grouted with epoxy mortar: as they are absorbent, they tend to absorb the epoxy resin contained in the mortar, causing irreversible stains. It is also necessary to consider the type of surface finishing (polished, hammered, etc.) in order to determine potential risk factors beforehand. Therefore, we recommend conducting a preliminary test to see exactly what the final appearance of the surface will be. Wooden or metal mosaics For this type of products, reactive adhesives (R2T) are usually recommended for gluing, such as LITOELASTIC or LITOCHROM STARLIKE, even if the back of the tile is made of plastic or resin. The most suitable choice of adhesive depends solely on the type of substrate (see Table 1). For grouting, you should always prefer an epoxy mortar like LITOCHROM STARLIKE. For the subsequent cleaning it is necessary to use detergents with an alkaline ph, such as LITONET New formula universal to avoid damaging the surface. Laying glass mosaic in bathtubs and swimming pools Leaving aside the choice of adhesive systems, already explained in Table 1, it should be highlighted that for this type of operation it is imperative to use mosaics mounted on paper or plastic film. Therefore mosaics mounted on nets must be avoided, since the adhesive usually employed to secure the net to the back of the tiles tends to emulsify due to prolonged contact with water. In this case too, it is best to use epoxy mortar for grouting operations, because it definitely extends the durability of the grouting.

6 6 MOSAIC WALL SPACERS As well as offering a wide range of products for laying and grouting mosaics, thanks to the well-established synergy with GENESIS, a UK leader in the production of profiles for ceramics, Litokol is able to offer a series of products dedicated to this type of materials. Namely, we would like to focus on an innovative system designed to facilitate the installation of mosaics in combination with ceramic tiles called MOSAIC WALL SPACERS. Stackable perforated PVC sheets measuring 15x30 cm that, when inserted in the layer of adhesive during installation, can recover thicknesses that vary from 2.5 to 5 mm, depending on where they are placed. In this way for the installer is much easier to match two materials, ceramic and mosaic, with two different thicknesses, without resorting to preventive levelling that would be difficult to carry out and would extend the installation time. This product may be used advantageously if you want to apply mosaic strips on walls covered with ceramic tiles. The sheets of MOSAIC WALL SPACERS are available in packs of 5 sheets each. WITHOUT Mosaic wall spacers WITH Mosaic wall spacers

7 7 There are also four types of aluminium profiles (art. EAM050, EMS050, TMG050, EMI050) to create interior and exterior angles of surfaces covered with mosaics, either right angles or rounded angles that are 5mm-thick. By inserting these profiles during laying operations, it is possible to give enhance the aesthetic value of the surface. Aluminium profile for EAM mosaic Jolly profile for EMS mosaic Aluminium profile for TMG mosaic Aluminium profile for EMI mosaic A valuable help for your work: view and download the technical insights FOCUS ON at LITOKOL S.p.A. Via G. Falcone 13/ Rubiera (RE) Italy Tel: Fax: info@litokol.it