Sealing Stained Concrete Patios: A Guide To Protection And Longevity

Sealing a stained concrete patio is a great way to protect and enhance the appearance of your outdoor space. Concrete patios that are not sealed are vulnerable to moisture, staining, and cracking in colder climates due to freezing water. By applying a sealer, you can prevent these issues and ensure your patio remains protected for years to come. The type of sealer you choose is important, with options including acrylic, epoxy, and urethane sealers, each offering different advantages and disadvantages. The sealing process involves several steps, from preparing the surface by removing dirt, grease, and paint, to applying multiple coats of sealer and allowing adequate drying time. It is also important to take safety precautions, such as wearing protective clothing and avoiding contact with the skin. With the right tools, knowledge, and assistance, sealing your stained concrete patio can be a successful DIY project that transforms your outdoor space.

Choose the right sealer for your concrete patio

There are several factors to consider when choosing a concrete sealer. The first is the type of sealer. There are three main types: acrylic, epoxy, and penetrating sealers.

• Acrylic sealers are either solvent-based or water-based. They are a good choice for simple application and low cost. They form a thin protective film that protects from moisture and chloride penetration while allowing water vapour to escape from the slab. They can be used on both interior and exterior concrete surfaces and are UV-resistant and non-yellowing.
• Epoxy sealers add a thick protective surface over the concrete and are highly water-repellent. They are used for floors in high-traffic areas or concrete countertops. They are subject to yellowing when exposed to UV light, limiting them to interior use.
• Penetrating sealers seal the pores of concrete below the surface, forming a chemical barrier that shields against moisture and chemical intrusion. They are typically breathable and nearly invisible, so they are a good choice for high-traffic exterior surfaces.

Other factors to consider include:

• The amount of area you need to cover and how many coats are required. Concrete sealers typically come in containers ranging from 1 quart to 5 gallons.
• The application type. Many sealers can be applied with a paint roller or pump sprayer, but always follow the manufacturer's guidelines.
• Drying time. The average drying time for concrete sealers is about 2 hours, but this can be extended due to weather conditions.
• Life expectancy. The longevity of the sealer will depend on how well it is applied and maintained. Thick, premium sealers like epoxies and urethanes will generally outlast acrylic sealers.
• TotalBoat Concrete Coating: a high-gloss, heat-resistant epoxy resin that works on various materials.
• Foundation Armor Concrete Sealer: an acrylic sealer that protects concrete surfaces from freezing, thawing, scratching, and scuffing.
• Ghostshield Siloxa-Tek Concrete Sealer: an environmentally friendly, water-based acrylic sealer that penetrates concrete surfaces and protects against chemicals, cracks, and stains.
• Black Diamond Stoneworks Stone Sealer: a glossy sealer that works on exposed aggregate, stamped concrete, coloured concrete, and other surfaces.
• RadonSeal Concrete Sealer: a penetrating sealer with a radon mitigation agent to protect against radon gas.
• Eco-Tuff Clear Coat Concrete Sealer: a non-toxic, plant-based, odourless sealer that provides excellent surface resistance.
• MasonryDefender Penetrating Concrete Sealer: an affordable, basic sealer that provides a long-lasting, non-glossy coat.

Remember, it is important to seal your concrete patio to protect it from moisture, stains, and wear and tear.

Prepare the concrete surface

Preparing the concrete surface is the most important step in the sealing process. Before applying any product, the concrete must be thoroughly cleaned and dried.

First, remove any dirt, dust, and debris from the surface with a stiff brush or broom. If there are any old paint, grease, or oil stains, these must be removed. Paint can be removed by blasting with sand or dry ice. Grease and oil stains can be removed with a detergent and water solution and a stiff brush. If this doesn't work, try a grease solvent or, for grease that has penetrated the concrete, a small amount of muriatic acid. Be sure to wear protective clothing when working with acid. Rinse the surface with clean water and allow it to dry.

For a really good clean, you could use a power washer or a tool called a Whisper Washer, which won't leave etch marks on the surface.

If there is any efflorescence (a white, powdery residue) on the concrete, use a mild acidic cleaner to remove it and then thoroughly rinse and neutralise the surface before sealing.

Once the surface is clean, make sure you're happy with the condition of the concrete. If it's very old or damaged, you may still see the old appearance through the stain.

Finally, wait for favourable weather before sealing. Concrete sealers need moderate temperatures for the best results, ideally between 5°C and 30°C, and no precipitation for at least three days.

Clean the concrete surface

To seal a stained concrete patio, you must first clean the concrete surface. Here are the steps you can follow:

Step 1: Remove Dirt and Debris

Start by removing any dirt, dust, or debris from the patio surface. You can use a stiff brush for this step or spray the concrete with water and let it dry for at least 24 hours.

Step 2: Deal with Paint, Grease, and Oil Stains

If there is old paint on the surface, you can remove it by blasting it with sand or dry ice. For grease or oil stains, add detergent to a bucket of water, pour it onto the affected area, and scrub with a stiff brush. If this doesn't work, try using a grease solvent or, for stubborn grease, a small amount of muriatic acid. Remember to always protect your skin when working with acid.

Step 3: Rinse and Dry

After removing stains, rinse off any residue with clean water and let the surface dry.

Step 4: Wash the Patio

Use a good washing tool, such as a pressure washer or a Whisper Washer, to thoroughly clean the patio. Avoid using a power washer too aggressively, as it can leave etch marks on the surface. Alternatively, you can scrub the concrete with a stiff broom and then rinse it with water.

Step 5: Deep Clean

For a more intensive clean, use a heavy-duty cleaner on the surface, working in small sections at a time, and then rinse with water. Repeat this process until there are no more soapy bubbles.

Step 6: Remove Tough Stains

For tough rust stains, use a stain remover followed by a water rinse. For grease or oil stains, use a product specifically designed to remove them. If there are kerfs (grooves) in the concrete, blast out any dirt and debris with water.

Step 7: Final Rinse and Dry

After cleaning, rinse the entire patio with water and let it dry for at least 72 hours before applying any sealers.

Apply the sealer

Sealing a stained concrete patio is a two-person job and will take about an hour for every 200 square feet of patio space. To apply the sealer, follow these steps:

• Choose a high-quality sealer: It is very important to choose the right product and read the directions carefully. Look for a sealer that is proven to work in your climate. For example, sealers that work in other environments may not hold up to Arizona's sun and heat. Techniseal, in the water-based Natural Look Matte Finish, offers the longest protection—up to 3 years.
• Cover up yourself and the surrounding areas: Wear long pants, closed-toe shoes, and long sleeves to protect your skin from the sealant. Cover your mouth and nose with a face mask, and wear glasses or goggles to protect your eyes from harsh fumes and potential splashback. Cover any plants, grills, and appliances, too.
• Secure the area: Keep people and pets from walking across the surface before it dries. Sealer can take several hours to dry completely, and dirty footprints or paw prints will leave a lasting impression that is not easily remedied.
• Prepare the surface: If you apply a sealer to a dirty patio, you will seal in the dirt and dull the finish. Begin with a good washing, using a tool like the Whisper Washer, which delivers a spray in a circular motion and won't leave pattern marks. Alternatively, you can use a power washer with a Whisper Wand attachment. After washing, wait at least 24 hours to allow the surface to dry.
• Apply the sealer: Using a bug sprayer, spray no more than 50 feet at a time with an even coat. Your partner should follow right behind you with a soft-bristled broom or paintbrush, working the sealer into the surface's pores and wiping up any liquid that pools or doesn't broom in. Apply one coat of a solvent-based sealer or two coats of a water-based product. It will dry in around 30 minutes.
• Apply a second coat: Allow the first coat to dry overnight before adding a second coat. If outside temperatures are low, allow an extra day to ensure the first coat is completely dry. Give the second layer a full 48 hours to cure. Then, hose it off with a garden hose and give it 10 days to allow the sealer to fully adhere.
• Final touches: After the 10-day waiting period, hose down the surface again and then spray on a top sealer. If you don't have a spray applicator, pour the sealer onto the damp surface and spread it with a brush instead. Before the coat is completely dry, apply a second, and allow a minimum of 36 hours before allowing foot traffic on the surface.

With a successful sealer application, your concrete patio should remain protected for a long time.

Allow the sealer to dry

Allowing the sealer to dry is a crucial step in the process of sealing a stained concrete patio. Here are some detailed instructions and considerations to ensure proper drying:

• Temperature and Weather Conditions: Maintain moderate temperatures, preferably between 5° Celsius and 30° Celsius, for effective application and curing. Avoid applying the sealer if the temperature is expected to drop below 5° Celsius or exceed 30° Celsius during the three-day period after application. Similarly, refrain from sealing if precipitation is expected during this curing period.
• Drying Time: Sealing stained concrete typically requires applying two thin coats of sealer. After applying the first coat, allow it to dry overnight or for at least two hours, depending on the manufacturer's instructions. For the second coat, give it a full 48 hours to cure. The total drying time for both coats can take up to three days.
• Foot Traffic: It is important to keep people and pets off the sealed patio until it is completely dry. Footprints or paw prints on the wet sealer can leave lasting impressions and are difficult to remedy. Wait for the recommended drying time before allowing any foot traffic on the sealed surface.
• Hosing and Top Sealer: After the sealer has cured for 48 hours, it is beneficial to hose down the surface with a garden hose. Then, allow an additional 10 days for the sealer to fully adhere and cure. After this 10-day waiting period, hose down the surface again and apply a top sealer or spray it on if you have a spray applicator.
• Final Drying: Once you have applied the top sealer, allow a minimum of 36 hours before permitting foot traffic on the stained concrete patio. This final drying period ensures that the sealer has fully cured and hardened, providing a protective and durable finish to your patio.

Frequently asked questions