A mosaic project is about more than just the tiles, stones, or colors you choose. The right adhesive, primer, grout, and maintenance products also determine whether your mosaic adheres properly, stays beautiful, and remains easy to maintain.
At Mosaicshop, you will find Mapei Ultramastic III and various colors of Mapei Ultracolor Plus, among other items. In this article, we explain what these products are suitable for. We also mention several other Mapei products that can be useful for specific applications, such as swimming pools, heat-resistant projects, or special substrates. These products are intended as a technical guide and are not necessarily all standardly available in our webshop.
Still, choosing is not always easy. A mosaic on a dry interior wall requires something different than a shower wall, swimming pool, terrace, or barbecue. The substrate also plays a major role: plaster, cement, existing tiles, wood, or natural stone each require a different preparation.
In this guide, we provide a clear overview of the most important Mapei products for mosaic projects. You will learn when to use which product, what to look out for, and when a product is less suitable.
Are you first looking for a general explanation of mosaic adhesive, such as the difference between PVA adhesive, silicone adhesive, adhesive paste, and cement-based adhesive? Then read our guide “Choosing the Best Mosaic Adhesive: A Complete Guide for Every Project”. This article focuses specifically on Mapei products and additional materials such as primer, grout, silicone, and maintenance.
Please note: this article is intended as a practical choice helper. When in doubt, always check the Mapei technical data sheet and the condition of your substrate before you begin.
1. Which adhesive do you use for mosaic?
We already have a separate guide about choosing mosaic adhesive per project type. In it, we compare PVA adhesive, silicone adhesive, adhesive paste, and cement-based adhesive, among others. In this article, we focus on Mapei products: for example, when do you choose Ultramastic III, and when does your project require a cement-based or specialist system instead?
In our webshop, you will find Mapei Ultramastic III, a ready-to-use adhesive paste for many interior applications. For certain specific projects, such as swimming pools or heat-resistant applications, other Mapei products are required. We discuss them below so you can better understand when Ultramastic III is or is not the right choice.
The right adhesive depends on the application. Are you working indoors or outdoors? On a wall or floor? In a dry room, shower, or swimming pool? And on what type of substrate is the mosaic being placed?
Mapei Ultramastic III: ready-to-use adhesive paste for many interior applications
Mapei Ultramastic III is available in our webshop. In our general adhesive guide, we discuss this type of product under the adhesive paste category: useful when you do not want to mix powder adhesive yourself and want to get started right away.
It is a ready-to-use white adhesive paste. You do not need to mix this adhesive yourself, which is convenient for smaller projects, hobby use, and DIY applications.
Ultramastic III can be used on various substrates, such as cementitious substrates, plasterwork, gypsum board, stable painted walls, and certain moisture-resistant wooden surfaces. The product can also be suitable in bathrooms and showers, depending on the substrate and application.
An interesting detail for creative mosaic makers: the white adhesive paste can be colored with pigment. As a result, in some artistic applications, the adhesive can also remain visible as part of the design, for example as negative space between mosaic pieces.
Do not use Ultramastic III for tiling that is permanently underwater, such as swimming pools or fountains. The product is also not suitable for substrates with rising damp.
In short: Ultramastic III is a practical choice for many simple interior applications, especially when you are looking for a ready-to-use adhesive. For permanently wet applications, it is better to choose a different system.
Mapei Adesilex P9: cement-based adhesive for indoors and outdoors
Mapei Adesilex P9 is not intended as a direct replacement for Ultramastic III, but as a technical option for situations where a cement-based adhesive is required.
Adesilex P9 is a cementitious tile adhesive that you mix with water yourself. This product is suitable for a wide range of indoor and outdoor applications.
Adesilex P9 can be used for ceramic tiles and mosaic on floors, walls, and ceilings. Applications such as underfloor heating, cement screeds, plasterboard, and existing tiled floors may also be possible, provided the substrate is suitable, dry, stable, and correctly prepared.
For plaster or anhydrite, pretreatment with Primer G is necessary. With existing tiled floors, the tiles must be securely attached and the substrate must not show any cracks.
Adesilex P9 is a good basic choice when you need a cement-based adhesive for a classic tile or mosaic project, indoors or outdoors.
Mapei Adesilex P10: for glass, ceramic, and marble mosaic
We mention Adesilex P10 primarily as a technical selection aid for specific applications, such as glass mosaic and swimming pool mosaic.
Mapei Adesilex P10 is particularly interesting for glass mosaic, ceramic mosaic, and marble mosaic. The product is suitable for vertical applications where the tiles must not slip during installation.
Adesilex P10 can be used, among other things, for mosaic on cement plasters, uneven substrates, and gypsum boards.
For swimming pools or basins, according to the product specifications, Adesilex P10 is combined with Isolastic, diluted with water according to the prescribed ratio. This combination is used for bonding mosaic onto plasterwork or onto substrates that have been waterproofed with Mapelastic.
Do not use Adesilex P10 on wood, particleboard, metal, rubber, PVC, or linoleum. The product is also not intended for applications where an adhesive layer thicker than 5 mm is required, or on concrete that has not yet sufficiently cured.
In short: Adesilex P10 is a targeted choice for glass mosaic, vertical installation, and certain swimming pool applications, but only when the complete system is applied correctly.
Mapegrout Refractaire: for ovens, barbecues, and fireplaces
Mapegrout Refractaire is a specialized product. We mention it because regular mosaic adhesive is not suitable for high temperatures. Check current availability when planning a project around an oven, barbecue, or fireplace.
For applications around high temperatures, do not use ordinary mosaic adhesive. Think of ovens, barbecues, fireplaces, chimneys, or flue pipes.
Mapegrout Refractaire is a heat-resistant mortar for brickwork that comes into contact with fire. The product can be used for bonding and grouting such applications.
The color is dark gray and the product is available as a pre-blended one-component mortar. For decorative mosaic projects around heat sources, this is therefore a different type of product than standard tile adhesives.
2. Primer: when do you need Primer G or Eco Prim Grip Plus?
Primer is not a product that you automatically use every time. Whether you need a primer depends mainly on the substrate.
An absorbent gypsum-like substrate requires a different preparation than a smooth, non-absorbent tiled wall. Applying the wrong primer can actually reduce adhesion instead of improving it.
Mapei Primer G: for absorbent substrates indoors
Mapei Primer G is used for preparing absorbent substrates, especially indoors. Think of gypsum plasters, spray plaster, anhydrite, plasterboard, and other substrates that must be treated before cement-based products are applied to them.
When using cement-based adhesive on certain interior substrates, Primer G is often an important step. On highly absorbent substrates, the product is applied diluted according to the guidelines.
Do not use Primer G outdoors. For outdoor applications, it is better to carefully follow the technical data sheet and substrate preparation guidelines. In practice, outdoor work often involves dampening the substrate instead of using Primer G.
Mapei Eco Prim Grip Plus: for smooth and non-absorbent substrates
Eco Prim Grip Plus is a ready-to-use primer for smooth or non-absorbent surfaces. Think of existing ceramic tiles, terrazzo, natural stone, or smooth surfaces such as certain resin floors.
This product is especially useful when you want to apply mosaic to a substrate that absorbs very little. An old glazed tile wall is a good example of this.
Eco Prim Grip Plus can be used indoors and outdoors, depending on the application and substrate.
3. Which grout do you choose?
In our webshop, you will find various colors of Mapei Ultracolor Plus. For many mosaic projects, that is the most relevant grout from this overview. The other grouting products below are useful for technical comparison, especially for situations where Ultracolor Plus is not the right choice.
Grout determines not only the appearance of your mosaic, but also the ease of maintenance and resistance to moisture, dirt, and heavy use.
For most ordinary projects, a cement-based grout is sufficient. For swimming pools, industrial applications, or environments where hygiene is important, epoxy grout can be a better choice.
Mapei Ultracolor Plus: all-round cement-based grout
Mapei Ultracolor Plus is available in our webshop in various colors. It is a fast-setting and fast-drying cementitious grout for joints up to 20 mm wide.
The product is suitable for floors and walls, indoors and outdoors. It can be used with various types of tiles and materials, including glass mosaic, ceramics, terracotta, stone, and marble.
Ultracolor Plus is water-repellent, mold-resistant, and developed to maintain a uniform grout color. This makes it a logical first choice for many mosaic projects.
Examples of applications include bathrooms, kitchens, living areas, facades, balconies, terraces, and other tiled surfaces.
Mapei Kerapoxy: epoxy grout for heavy duty use and swimming pools
Kerapoxy is a specialized epoxy grout. We mention this product primarily to make it clear when a regular cement-based grout like Ultracolor Plus might not be sufficient.
Mapei Kerapoxy is a two-component epoxy product. It is more resistant to chemical exposure and is easier to clean thoroughly than a standard cement-based grout.
Kerapoxy is particularly interesting for swimming pools, industrial floors and walls, kitchens, laboratory benches, food preparation areas, and other environments where hygiene or chemical resistance is important.
For swimming pools, Kerapoxy is a strong choice, especially with salt or thermal water.
On the other hand, epoxy grout is more expensive and less easy to work with than cement-based grout. Therefore, choose Kerapoxy primarily when the application demands it.
Mapei Fuga Fresca: recoloring existing grout joints
Fuga Fresca is not a traditional grout, but a ready-to-use polymer paint for existing cementitious joints.
You use it to refresh old grout joints or change their color indoors. It is suitable for walls and floors inside.
Fuga Fresca does not replace damaged, loose, or crumbling grout. In such cases, the joint must first be technically repaired.
Mapei Keracolor Rustic: wide joints with a rustic look
Keracolor Rustic is intended for wide joints from 5 to 50 mm. The product has a coarser grain and provides a rustic appearance.
It is used for terraces, pool decks, and wall claddings, among other things. Suitable materials include natural stone, porcelain tiles, terracotta, facing bricks, marble, and granite.
Keracolor Rustic is particularly interesting when the joint is intentionally allowed to be wide and visible.
4. Quick choice helper for grouts
| Situation | Recommended product | Why |
|---|---|---|
| General mosaic project indoors or outdoors | Ultracolor Plus | Versatile cement-based grout |
| Bathroom or shower | Ultracolor Plus | Water-repellent and mold-resistant |
| Swimming pool or basin | Kerapoxy | Suitable for heavy moisture loads and swimming pools |
| Kitchen or hygienic space | Kerapoxy | Easy to clean and suitable for hygienic applications |
| Wide rustic joints | Keracolor Rustic | For joints from 5 to 50 mm |
| Recoloring old interior joints | Fuga Fresca | For refreshing cement-based joints |
5. Protecting tiles before grouting
With porous tiles, grout can seep into the pores. This can cause staining or make cleaning up after grouting more difficult.
UltraCare Grout Release
UltraCare Grout Release is a water-based product that is applied before grouting. It forms a thin, temporary protective layer on the tile, so that cementitious grout is less likely to penetrate into the micropores.
This is especially useful for porous materials such as marble, terracotta, clinker bricks, natural stone, composite, or textured tiles.
Apply the product very thinly. It is intended as temporary protection during grouting and is removed afterwards during cleaning.
Important: UltraCare Grout Release is only suitable for cement-based grouts, not for epoxy grouts.
6. Silicones for finishing and joints
You do not use silicone as a grout for the entire tiled surface. It is used for sealing between two elements, for example in corners, along edges, around sanitary fittings, or between walls and floors.
Mapesil AC
Mapesil AC is an acetic-crosslinking (vinegar-based) silicone. The product is available in a wide range of colors, including transparent. This allows it to be matched well with the color of the grout.
Mapesil LM
Mapesil LM is low-odor and neutral (neutral-cure, without vinegar). It is available in a more limited number of colors, plus transparent.
Mapesil AC therefore offers the widest color choice. Mapesil LM can be more pleasant when you are looking for a low-odor product. Which variant is most suitable also depends on the substrate and application.
7. Cleaning and maintenance of grout joints
Maintenance remains important after installation. Grout joints in particular can absorb dirt or become discolored over time.
UltraCare Grout Cleaner
UltraCare Grout Cleaner is a cleaner for both cement-based and epoxy grouts. The product can be used on walls and floors, indoors and outdoors.
It is suitable for various surfaces such as ceramics, porcelain tiles, terracotta, clinker bricks, glass mosaic, cement tiles, and certain natural or engineered stones.
Do not use it on polished natural or engineered stone, and do not use it on surfaces treated with wax.
UltraCare Grout Protector
UltraCare Grout Protector protects cementitious grout joints and porcelain tiles against stains. The product does not form a visible film and does not alter the appearance of the surface.
The protection can be renewed periodically, depending on use and exposure. The product can be used indoors and outdoors on walls and floors.
A logical maintenance sequence is: first clean with UltraCare Grout Cleaner and then protect with UltraCare Grout Protector, if the application is suitable for it.
8. Practical choice table per project type
The table below helps you choose. Products available in our webshop, such as Ultramastic III and Ultracolor Plus, can be viewed directly. For specialized products or applications, we recommend checking current availability and the technical data sheet.
| Project type | Adhesive | Primer | Grout | Extra product |
|---|---|---|---|---|
| Mosaic on dry interior wall | Ultramastic III or Adesilex P9 | Primer G for suitable absorbent substrates | Ultracolor Plus | — |
| Mosaic in bathroom or shower | Ultramastic III or Adesilex P9 | Dependent on substrate | Ultracolor Plus | Mapesil AC or LM for expansion joints/edges |
| Glass or marble mosaic vertically | Adesilex P10 | Dependent on substrate | Ultracolor Plus or Kerapoxy | Grout Release for porous tiles |
| Mosaic outdoors | Adesilex P9 | No Primer G; follow outdoor guidelines | Ultracolor Plus or Keracolor Rustic | — |
| Swimming pool mosaic | Adesilex P10 + Isolastic according to instructions | Dependent on system | Kerapoxy | Verify complete technical buildup |
| Mosaic on existing tiles | Adesilex P9 or Adesilex P10 + Isolastic, depending on application | Eco Prim Grip Plus | Ultracolor Plus | — |
| Mosaic around oven or barbecue | Mapegrout Refractaire | — | Mapegrout Refractaire | Only use a system suitable for heat |
| Porous tiles or natural stone | Dependent on tile and substrate | Dependent on substrate | Ultracolor Plus | UltraCare Grout Release before grouting |
| Refreshing old interior joints | — | — | Fuga Fresca | Only on existing cement-based joints |
9. Frequently Asked Questions
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No. Ultramastic III is not suitable for tiling work that is permanently underwater, such as swimming pools or fountains. For swimming pool mosaic, Adesilex P10 combined with Isolastic is recommended for bonding. For grouting, Kerapoxy is a suitable choice, especially with salt or thermal water.
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No. Primer depends on the substrate. Gypsum, anhydrite, or smooth existing tiles often require preparation, but that does not mean the same primer is suitable everywhere. Primer G is intended for indoor use on suitable absorbent substrates. Eco Prim Grip Plus is intended for smooth or non-absorbent substrates.
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Ultracolor Plus is a cement-based grout for many general applications. Kerapoxy is an epoxy grout for harsher conditions, such as swimming pools, hygienic spaces, industrial applications, or places where chemical resistance is important.
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No. Fuga Fresca is intended for indoor use. It is a product to refresh existing cement-based joints or change their color, not to apply new joints outdoors.
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Use UltraCare Grout Release before grouting when working with porous or textured tiles that are prone to staining from cement-based grout. The product helps to remove residues more easily after grouting.
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Silicone is used for connections, edges, and movement joints, for example between walls and floors or around plumbing fixtures. Do not use silicone as a replacement for grout across the entire tiled surface.
10. Conclusion
Choosing the right Mapei product starts with your project. A dry indoor wall, shower, terrace, swimming pool, or oven requires a different approach each time.
Are you not yet sure what type of adhesive you need in general terms? Then start with our guide “Choosing the Best Mosaic Adhesive: A Complete Guide for Every Project”. If you already know you want to work with Mapei products, then this guide will help you better place the right adhesive, primer, grout, and maintenance products.
Pay close attention to these factors in particular:
- the substrate;
- indoor or outdoor application;
- dry, wet, or permanently underwater environments;
- the type of mosaic or tile;
- the joint width;
- the load and maintenance requirements;
- any heat, hygiene, or chemical requirements.
For many general mosaic projects, Mapei Ultramastic III and Mapei Ultracolor Plus are practical products that you can find in our webshop. For more specific situations, such as glass mosaic, swimming pools, porous tiles, or high temperatures, other Mapei products may be required. These are not necessarily standard in our webshop, but we can help assess which system is technically suitable.
View the available Mapei products in our webshop or contact us if you are unsure which product is right for your project.
