Why protect decorative concrete?
First of all, it must be understood that concrete, decorative or not, is a porous material. When used for decorative purposes, it still requires protection suitable for the final destination of the project. A multitude of products exist for the protection of concrete.
They can be categorized according to their level of protection.
1. Aqueous phase or solvent ?
At first, it is necessary to become familiar with the essential vocabulary to know and recognize these different products.
The so-called "aqueous-phase" or "aqueous-based" products are formulated on a water basis. This means that they have a very light smell and that they release little or no VOCs (Volatile organic compounds).
"Solvent phase" products are mainly derived from petrochemical. They consist of an organic solvent which serves as a base for an assembly of resins. These products are generally more harmful and all contain VOCs. The performance of a solvent-based varnish depends on the percentage of resin contained in it: a varnish containing 50% resin performs better than one containing only 40%. Their use is reserved for professionals and require appropriate respiratory protection and clothing.
Note: As a general rule, water-based products are not compatible with solvent-based products. If you have to apply several successive coats, apply products from the same family.
2. Penetrating sealers
These products must be considered as the first level of protection for concrete. They offer minimum protection against water and base oils. These are very liquid products which are applied as the first coat. They will be completely absorbed by the porosity of the concrete. As a general rule, they are invisible and do not or only slightly change the initial appearance and color of the concrete.
- Advantages: Invisible protection without change in appearance
- Cons: Time-limited protection
3. Single-component products - Varnish or resin
These are products consisting of a single component. In aqueous or solvent phase, they are easy to apply because they are ready to use. They can be applied in addition to a pore sealer or in several layers.
- Pros : Economical and easy to use
- Cons : Fairly limited level of protection against stains
4. Bi-component products - Varnish or Resin
As the name suggests, these products consist of two components : a resin and a catalyst. A precise mixture between these two products is necessary before application. The use of a scale is essential because the proportions to be respected are always given by weight. Once the mixture is assembled, it should be applied fairly quickly and carefully using a paint roller.
A two-component varnish constitutes, beyond measure, the best durable and maintenance-free protection of decorative concrete against all types of stains: water, oils, wine, coffee, lemon, vinegar, etc...
- Advantages: Film-forming protection with exceptional protection
- Cons: Precision mixing to be done before application
Note: A two-component product is always more efficient than a single-component. The assembly of the two components (resin + catalyst) generates a phenomenon of polymerization which optimize the resistance of the final product.
5. Polyurethane or epoxy varnish ?
The two-component varnishes described above are generally formulated on a polyurethane or epoxy base. These products both offer excellent performance in terms of resistance and protection against stains. On the other hand, the epoxy component has a major defect: it yellows when exposed to UV rays. ALL epoxy-based varnishes, without exception, yellow to a greater or lesser extent under UV.
Consequently, it is not recommended to use these varnishes outdoors, and even indoors, in spaces exposed to direct sunlight. Preferably use polyurethane-based varnish.
6. Impregnator and vitrifier
These products are two-component intended for the protection of so-called "closed" supports. Unlike "classic" two-component products that are often quite thick, they are, on the contrary, very fluid. this fluidity allows good penetration into the least porous substrates such as industrial floor slabs.
- Pros: Excellent fluid protection
- Cons: Mixture to be made with precision
7. Waxes and oils
For information, you should know that the first decorative concretes were once protected with waxes or oils. Even if the level of protection of these products was considered "correct" at the time, they are now abandoned for questions related to their maintenance.
The oils
For oils, the process consisted of saturating the concrete by soaking it with oil. Thus treated, the concrete was no longer able to absorb other stains from other products. On the other hand, it was advisable to maintain this oil saturation regularly. Considered too restrictive, this type of protection is abandoned nowadays.
Waxes
20 years ago, the wax was generally applied after a layer of filler.
However, while some waxes are of high quality, they all require regular maintenance, specifically for floors. Indeed, the life of a wax is limited in time. Successive cleanings with detergents degrade the waxes as well as the usual abrasion. It is therefore advisable to regularly maintain a waxed floor, by renewing the surface layer. This maintenance constraint has led users to turn to more durable products such as two-component varnishes.
Note: Wax can also be used to "overprotect" varnish. In very busy spaces such as public places or shops, it is possible to use a layer of wax to protect the varnish from micro-scratches.