Overview of Common Concrete Sealer Options
The following is an introduction to the most common types of sealers that are recommended for concrete. Left untreated, concrete is a naturally porous material and will act like a sponge. It may trap oils or staining agents in its capillaries which will be difficult to remove. Some concrete is more porous and may have a gritty texture and some very dense that is polished mirror smooth.
No matter what, it is a good idea to use a recommended concrete sealer and understand what to expect. There is no single sealer that works for all circumstances and all users. Every sealer has pros and cons that must be considered for a given project. It is important to understand your project and know what is required of the sealer. And it is always a good idea to make a sample project and test the sealer to determine suitability.
Sealer Types - There are 3 basic categories of sealers: 1. Penetrating, 2. Topical Coatings and 3. Hybrid Reactive.
- Penetrating Sealers - Penetrating sealers like silanes, siloxanes, and fluoropolymers are applied to fill the pores of the concrete. Once the concrete is saturated it will not accept any more material. Some penetrating sealers are also reactive. Silicates are dispersed in a solution of sodium, potassium or lithium and provide some protection through densification. They penetrate the concrete and react with the calcium hydroxide (free lime) present to form more CSH, the binding ingredient that hardens concrete. These accelerate the hardening of the concrete and are often used when polishing to a high sheen.
Buddy Rhodes Penetrating Sealer is typically used as the first step in a sealing process, followed by applications of Buddy Rhodes Satin Sealer. Penetrating sealers on their own provide limited protection against acids. If a stain occurs or etches into the concrete the repair would be to sand or polish the area to remove the defect. This process will often expose sand and aggregate beneath the surface, changing the appearance of the countertop if there was no exposure previously present.
- Topical Coatings – Topical Coatings are film forming barriers that are applied to the surface of the concrete to impede infiltration of staining agents. All coatings will scratch and wear over time, some more readily and apparent than others. Eventually they may need to be re-applied. Generally, the thicker the coating, the more stain protection, but the easier and more severe the scratching can occur.
Topical Coatings are often not preferred for exterior use. Because concrete acts as a sponge, exterior concrete can absorb atmospheric moisture with seasonal weather conditions. This excess moisture may become trapped beneath the surface of the sealer causing an irreversible “whitening” condition, or worse, delamination.
Common Topical Coating chemistries include acrylic, polyurethane, and epoxy:
- Acrylic can be water based or solvent based and are the easiest to apply, but they scratch the easiest. They offer moderate protection against stains and acids. The sheen is natural to high gloss. Buddy Rhodes Satin Sealer is a water based acrylic sealer, typically used in conjunction with Buddy Rhodes Penetrating Sealer.
- Urethane sealers can be single- or multi-component and either water based, or solvent based. They have good scratch resistance and have very good stain resistance and acid protection. They may be gloss to matte finish. Buddy Rhodes Reactive Polyurethane Sealer is a high-performance water-based urethane coating.
- Epoxies are multi-component and may be water based, solvent based or 100% solid content. Epoxy coatings usually applied to a thick, plastic-looking finish. They also scratch easily but have excellent stain and acid protection. They are high gloss. Smooth-On’s Tarbender is a suitable epoxy coating.
- Wax, such as Buddy Rhodes Beeswax, may be used as a sacrificial layer over another sealer. This can extend the life of the underlying sealer but does not offer enough protection to be used as a stand-alone topical coating. The downside to wax is that once it is introduced to the porous concrete surface, it is nearly impossible to fully remove, making localized sealer repair very difficult.
- Hybrid Reactive - Hybrid Reactive sealers combine the benefits of reactive penetrating sealing technology and a micro-coating technology together in one single product. ICT PS1 and ICT PS1-LS are two examples of hybrid reactive sealers. These sealers react with the concrete chemistry and form a “glass-like” surface on the concrete and builds protection over time. It is best to think of this sealer as a “treatment” rather than a coating that is applied.
These sealers have a learning curve associated with the application, and therefore do not always perform as expected due to one or more variables. They perform best when applied to quality, high performance concrete that was made from a specific concrete countertop mix design with a low water to cement ratio that has been properly cured. Hybrid Reactive sealers need time to react with the ingredients in the concrete to build stain resistance. Therefore, it is best to clean any spill or staining agent immediately for the first 1-2 months after initial sealer application. But once the resistance is achieved, they are very easy to maintain. They are also easily repaired to a localized area, should need arise. This sealer is a good option for using outdoors where topical coatings are less suitable.
Picking the correct sealer for a project is crucial and setting expectations is the first step. If you are sealing an accent table or fireplace surround, a simple penetrating sealer would perform just fine. If the table is exposed to red wine spills frequently, a topical coating sealer may be a better option for added protection. A working kitchen environment exhibits the most adverse conditions for any sealer. Staining agents, hot pans and scratches can take their toll on a sealer, but you can repair a sealer application much easier than the concrete countertop. For this reason, a topical coating sealer, or a hybrid reactive sealer which has fully developed its reaction, are the most recommended sealers for kitchen countertops.
The final word on sealers is that they all work as they are designed to, within the constraints of their chemistry. Some are easier to apply. Some offer better protection for certain staining agents. You must select the sealer that best matches the highest number of project requirements. You can use our Sealer Quick Reference & Selection Guide to narrow your options, but there is no substitute for personally testing the sealers on your own samples. Without this first-hand experience, you are setting yourself up for failure at some point.