What Is The Best Sealer For Clay Pots?
Clay pots and planters are popular for indoor and outdoor plants because of their natural, earthy look. However, the porous nature of clay allows water to seep through, resulting in soil drying out faster. Applying a sealer to the inside of a clay pot helps prevent water absorption so the plant stays properly hydrated. Determining the most effective sealer depends on considerations such as exposure to sun, flexibility of the seal, and your budget. This guide will explore the leading types of sealers for enhancing water retention in clay pots.
Porosity of Clay
Clay is a porous material full of microscopic holes that absorbs water. When unglazed clay pots are used to hold water, the water slowly seeps through the pores in the clay walls. Over time this makes clay pots lose their structural integrity as the material expands and softens. Sealing the clay is necessary to prevent this absorption and water damage.
Preventing Water Absorption
Clay is naturally porous and will absorb and hold water if left unsealed. This can lead to several issues:
- Absorbed water can cause the clay to crack as it expands.
- Trapped moisture provides an environment for mold and bacteria to grow.
- Liquid contents can leak through unsealed terra cotta pots.
Applying an appropriate sealer creates a waterproof barrier that prevents absorption and leakage. This protects the structural integrity of clay pots and planters, while also inhibiting mold growth and accidental spills.
High-quality sealers seal the pores on both the interior and exterior surfaces of terra cotta. This provides complete waterproofing and leak protection.
Types of Sealers
There are four main types of sealers commonly used for clay pots:
Acrylic Sealers
Acrylic sealers are water-based and penetrate into the clay to create a protective barrier. They are non-toxic and fast-drying. Acrylic sealers are easy to apply with a brush and provide a matte finish.
Varnish Sealers
Varnish sealers contain resins dissolved in a solvent. They form a hard, glossy coating on the surface of the clay. Varnish seals in moisture and provides good protection. Application requires careful brushwork to avoid drips.
Epoxy Sealers
Epoxy sealers are two-part products that create a plastic-like coating. They offer excellent adhesion, durability and water resistance. Epoxy sealers are more difficult to apply than other options but provide the strongest protective barrier.
Polyurethane Sealers
Polyurethane is a clear, durable plastic coating that dries to a glossy finish. It provides excellent protection against moisture and stains. Polyurethane can yellow over time and requires careful application to avoid drips.
Acrylic Sealers
Acrylic sealers are budget-friendly options for sealing porous clay. They penetrate the clay’s surface and provide a flexible, waterproof barrier within the clay. Acrylic solutions are typically water-based and dry to a clear, matte finish.
The main advantage of acrylic sealers for clay pots is their ability to soak into the porous clay body. As the water or solvent evaporates from the acrylic solution, the acrylic polymers are deposited within the clay’s pores. This helps prevent water from being absorbed into the clay, reducing the risk of damage from freezing and thawing cycles.
Acrylic sealers are also quite affordable, especially compared to epoxy or polyurethane options. Many acrylic sealers can be purchased for less than $20 per quart. For sealing a large number of basic clay pots, acrylics present a budget-friendly solution.
The downside is that acrylic sealers generally do not provide as thick or durable of a coating as other options. They may require more frequent reapplication. Acrylics also do not provide a glossy wet look. But for basic indoor or outdoor clay pot sealing, acrylics offer an easy and inexpensive option.
Varnish Sealers
Varnish sealers provide a glossy, finished look to clay pottery. They are made from resins dissolved in solvents, which allows the sealer to penetrate into the clay. As the solvent evaporates, the resin remains behind, sealing the pores of the clay.
Varnish forms a protective film over the surface of the clay, enhancing the natural colors. It leaves behind a surface sheen from glossy to satin, depending on the type of varnish used. The glossy finish is visually appealing but can also highlight imperfections in the clay.
While varnish seals the surface, it does not make the clay fully waterproof. The coating fills the pores but does not create an impermeable barrier. Over time, moisture can still seep in through unglazed areas of the clay. Varnish also requires occasional reapplication, as it can wear away with regular use and washing.
Epoxy Sealers
Epoxy sealers are often the best choice for sealing clay pots. They typically consist of a two-part epoxy resin and an epoxy hardener that cure together to form a durable, plastic-like coating. Once applied and cured, epoxy sealers form a waterproof barrier on the pot’s surface, effectively preventing water from penetrating the clay’s porous surface. The epoxy cures into a thick, hard coating that fully seals the outside and inside surfaces of the pot.
In addition, epoxy sealers are extremely durable and long-lasting. They are more resistant to scratches, impact, and wear compared to other sealers like acrylics and varnishes. The chemical bonding process that occurs during curing allows epoxy to form very strong bonds that are difficult to deteriorate. Epoxy’s durable plastic coat protects clay pots from damage while providing an impenetrable moisture barrier.
Epoxy seals maintain their protective qualities even when exposed to weathering, sunlight, water, and freezing temperatures better than other options. This makes epoxy sealers a great choice for outdoor clay pots or any pieces that will come into frequent contact with moisture. The rock-hard finish will hold up for years of use. For crafters and artists looking to seal clay work with maximum durability, epoxies offer superior performance.
Polyurethane Sealers
Polyurethane sealers provide a flexible, transparent finish that protects clay pots from water damage. Polyurethane forms a durable plastic coating that adheres well to the porous clay surface. The flexibility of the finish allows it to expand and contract with temperature changes without cracking or peeling.
Polyurethane sealers are available in both water-based and oil-based formulas. Water-based polyurethane dries more slowly than oil-based, but it has less odor and fewer VOCs. Both types provide good protection for indoor and outdoor clay pots.
Polyurethane sealers resist UV rays, chemicals, and abrasion better than many other clay pot sealers. They help prevent the leaching of minerals through the clay that can leave unsightly stains down the sides of pots. The coating is also resistant to mildew and algae growth.
Most polyurethane sealers require two or three coats for best protection, with light sanding between coats. Properly applied, polyurethane sealers can last up to 3 years on clay pot surfaces outdoors. They provide a natural look that enhances the clay’s natural tones.
How to Apply Sealers
Proper application is key to getting the most out of a sealer. Make sure to thoroughly clean the clay pot first, removing any dust or debris. Allow the pot to completely dry before applying any sealer. Sealers bond best to a dry, porous surface.
Apply the sealer in thin, even coats according to the manufacturer’s instructions, usually using a brush or clean cloth. Thin coats are better than one thick coat. Allow each coat to fully dry before adding another. Two or three thin coats often work better than a single thick one. Avoid over-application that leads to drips or pooling.
Work in a well-ventilated area and carefully follow all safety precautions listed on the sealer product. Make sure to reseal clay pots every year or two to maintain their water resistance and aesthetics. With proper sealing application, clay pots can remain protected from the elements.
Choosing the Best Sealer
When selecting the best sealer for clay pots, there are a few key factors to consider:
Porosity – More porous clay will absorb more sealer, so an acrylic sealer is a good budget-friendly option for highly porous clay. Less porous surfaces only need a thin coat, so a polyurethane provides good durability without wasting extra product.
Budget – Acrylic sealers are the most affordable option starting around $10 per quart. Varnishes are mid-range around $15-30. Epoxy and polyurethane cost $30-50 but provide the most durability.
Durability – Acrylics last 1-2 years outdoors. Varnish lasts 2-4 years. Epoxy and polyurethane last 4+ years and provide the best longevity. Consider how long you need the sealer to last.
The best balance for most clay pot sealing needs is typically a mid-range varnish sealer. Varnishes provide decent durability for 2-4 years, easily seal porous clay, offer UV resistance, and are budget-friendly at around $15-30 per quart. For indoor pieces, acrylic sealers are sufficient, while epoxy or polyurethane work well for highly durable outdoor pots.
