Yes, absolutely. Sealing is not just recommended for terrazzo. it is a critical and essential step in its installation and long-term maintenance.
Think of the sealant as terrazzo's invisible, protective shield. Here's a detailed breakdown of why it's mandatory, how it works, and what happens if you skip it.
Why Sealing is Non-Negotiable
1. It's Porosity (Despite Appearances): While the chips (marble, glass, quartz) and the epoxy resin binder are themselves non-porous, the matrix (the cement or epoxy holding it all together) and any microscopic pits or fissures can allow liquids to penetrate. Sealing fills these pores.
2. Stain Prevention: This is the primary job of a sealant. An unsealed terrazzo floor will absorb spills like wine, coffee, oil, or juice, leading to permanent, discolored stains.
3. Protection from Etching: Many terrazzo floors contain marble or limestone chips, which are calcium-based and highly reactive to acids. A strong sealant prevents acidic substances (lemon juice, vinegar, some cleaners, soda) from contacting and "etching" the stone. Etching appears as dull, light-colored spots where the polish has been chemically burned away.
4. Ease of Cleaning: A sealed surface is smooth and non-porous, meaning dirt and grime sit on top and can be easily wiped away with a damp mop. An unsealed surface will trap dirt in its pores, making it much harder to clean thoroughly.
5. Enhances Shine and Color: A good sealant brings out the deep, rich color of the aggregate and gives the floor a brilliant, glossy finish that is characteristic of classic terrazzo.
Types of Sealers for Terrazzo
There are two main types, and the choice often depends on the type of terrazzo and its location:
1. Impregnating Sealers (Penetrating Sealers):
- How they work: These sealers penetrate into the pores of the terrazzo itself and form a protective barrier within the material, without leaving a noticeable surface film.
- Pros: They preserve the natural look and feel of the floor. They are very durable and don't alter the slip resistance. They are "breathable," allowing moisture vapor to escape from the substrate.
- Best for: All types of terrazzo, but especially for cementitious terrazzo or floors over a moisture-prone substrate.
2. Topical Sealers (Surface Sealers):
- How they work: These create a protective coating or film on top of the terrazzo surface.
- Pros: Can provide a very high-gloss, wet-look finish and are often extremely durable.
- Cons: They can wear away with heavy traffic, requiring more frequent reapplication. They can sometimes yellow over time or become slippery when wet if not formulated correctly. They are not "breathable."
- Best for: Epoxy-based terrazzo or areas where a specific high-gloss look is desired. Must be chosen carefully.
Important Note: Modern terrazzo, especially epoxy terrazzo, is less porous than traditional cement terrazzo. However, it is still universally recommended to seal it for maximum protection against staining and etching.
What Happens If You Don't Seal Terrazzo?
An unsealed terrazzo floor is vulnerable to:
- Staining: Spills will become permanent.
- Etching: Dull spots from acidic materials will appear everywhere.
- Dull Appearance: It will quickly lose its shine and look dirty and old.
- Difficult Cleaning: It will require harsh scrubbing to get clean, which will further damage the surface.
- Bacterial Growth: Moisture and organic matter can seep into the pores.
How Often Does It Need to Be Re-Sealed?
Sealing is not a one-time event. The sealant wears down over time from foot traffic, cleaning, and general use.
- Frequency: Typically, terrazzo should be re-sealed every 3 to 5 years for residential use, and more frequently (1-3 years) in high-traffic commercial areas.
- The Water Test: You can easily check if your terrazzo needs sealing. Sprinkle a few drops of water on the floor in a few different spots. If the water beads up, the seal is still good. If the water darkens the stone and is absorbed within 5-10 minutes, it's time to re-seal.
Conclusion
Yes, you absolutely must seal terrazzo. It is a fundamental part of the installation process and the single most important factor in ensuring your terrazzo floor remains beautiful, stain-resistant, and easy to maintain for its incredibly long lifespan. Always consult with your installer on the best type of sealer for your specific terrazzo floor.
