How to Choose the Best Concrete Sealer
Water and moisture intrusion, freeze-thaw damage, ice melt damage, chemical stains, mold and mildew, sunlight, cracking – Your concrete is being attacked by harsh environmental factors from the day it was poured. All these concrete surface problems can be avoided, and indoor and outdoor concrete will last much longer if you apply the right concrete sealer.
We carry a solution for all types of concrete, in any location, at any age. Brushed concrete, stamped concrete, interlocking pavers, acid-stained floors, or exposed-aggregate walkways; the correct sealer can restore beauty and ensure the surface will look its best and function well for years to come.
Here are some of the basics you need to know when choosing the correct concrete sealer or cement sealer.
Types of Concrete Sealers
These concrete sealers (Silane, Siloxane, Silicates, and Siliconates), as their name suggests, work by penetrating and absorbing into concrete below the surface. Concrete is extremely porous. Water and fluids are easily absorbed causing all sorts of damage if the concrete is left unsealed. By using a penetrating sealer, water and fluids bead up on the surface while simultaneously sealing the interior pores of the concrete. Penetrating sealers are breathable, clear, and very easy to use. They can be applied by using a low-pressure garden pump sprayer, a paint roller, or a brush.
- Penetrating sealers waterproof concrete
- Penetrating sealers prevent freeze-thaw damage
- Penetrating sealers protect surfaces from de-icing salts, ice melt, or rock salt
- Penetrating sealers reduce cracking, pitting and spalling
- Penetrating sealers do not change the appearance of the concrete
- Penetrating sealers are not slippery when wet or cold
Best used on:
- Concrete driveways and concrete walkways, stamped concrete pool decks, garage floors, concrete basements, cinderblock, stucco and brick chimneys
Best Ghostshield Penetrating Sealer Products:
- Siloxa-Tek 8500: Penetrating Water & Salt Repellent
- Siloxa-Tek 8505: Penetrating Water, Salt & Oil Repellent
- Siloxa-Tek 8510: Penetrating Water, Salt & Oil Repellent +
- Lithi-Tek 9500: Penetrating Waterproofer & Densifier
Unlike penetrating sealers, acrylic sealers coat the concrete surface with a protective film. The protective film leaves a decorative, wet look finish. Water-based sealers are low gloss, low VOC, and have low odor. Solvent-based sealers are high gloss, have greater color enhancement, and will last longer. Acrylic sealers are often used to restore dull, faded concrete. Acrylic sealers are easy to use on indoor and outdoor concrete.
- Acrylic sealers are UV resistant and non-yellowing
- Acrylic sealers protect against water absorption
- Acrylic sealers enhance colored and textured concrete, stamped concrete and pavers
- Acrylic sealers leave wet look high gloss and wet look low gloss finishes
- Acrylic sealers have shorter lifespans than penetrating sealers
Best used on:
- Stamped concrete driveways, walkways, pool decks, patios, pavers, stained or colored concrete
Best Ghostshield Acrylic Sealer Products:
- Cryli-Tek 5505: High- Gloss, Wet Look, Solvent-Based Decorative Sealer
- Cryli-Tek 5500: Low-Gloss, Wet Look, Water-Based Decorative Sealer
Epoxy Coating and Urethane Coating
Like acrylic sealers, epoxy coatings and urethane coatings add a thick protective coating to a concrete surface. They are used on interior concrete floors with a high risk of exposure to chemical spills, fuel, heavy equipment and high foot traffic. Epoxy coatings are known for their tenacious adhesion to concrete and are often used as a base coat primer in conjunction with a urethane topcoat. Applied like a concrete paint, epoxy floor coatings are applied with a paint roller or brush and the surface of the concrete is prepped using a floor grinder or muriatic acid.
- Epoxy coatings and urethane coatings provide a hard, long-lasting finish
- Epoxy coatings and urethane coatings are able to resist abrasions and heavy vehicular and forklift traffic
- Epoxy coatings and urethane coatings are able to stop the absorption of fuel and chemical spills
- Epoxy coatings and urethane coatings are available clear, colored, metallic or can be used with paint chips/flakes
- Epoxy coatings and urethane coatings are twice as durable and last twice as long as acrylic sealers
- Moisture vapor barrier epoxy coatings are able to stop water and waterproof concrete floors before the installation of carpet, tile and wood flooring
Best used on:
- Indoor concrete: warehouse floors, shop floors, garage floors, basement floors, kennels
Best Ghostshield Epoxy Coating and Urethane Coating Products:
- Epoxy 325: Interior Semi-Gloss Durable Primer & Coating
- Urethane 645: Interior High-Gloss Durable Coating
- Wear-Tek 4400: Interior & Exterior Moisture Cured Urethane Coating
- Vapor-Tek 440: Moisture Vapor Barrier Epoxy Coating
Concrete colorants, water-based concrete stains, acid stains, acetone stains and solid color concrete coatings are designed to enhance, rejuvenate and decorate concrete and pavers. Concrete paint and concrete stain can transform an entire pool deck, patio, office, floor or garage into a custom-colored oasis. Cement stains can hide imperfections in old or new concrete or hide concrete repair.
- Concrete stains transform the appearance of concrete by adding color
- Concrete stains highlight concrete’s natural beauty
- Concrete stains create a more uniform color and hide imperfections
- Concrete stains can be mixed or applied separately resulting in endless color options
Best used on:
- Concrete, concrete overlays, stamped concrete, pavers, concrete patios, stamped concrete pool decks and walkways, concrete floors, garage floors and concrete driveways
Best Ghostshield Concrete Stain Products:
Considerations When Choosing a Concrete Sealer
How Much Moisture is in the Concrete
Moisture levels need to be considered when applying or choosing a concrete sealer. Moisture usually comes from exterior sources, like water migrating from the ground underneath the slab, into the concrete (in the absence of a vapor barrier). Both evaporating water and pooled water can also interfere with a sealer.
A moisture measuring device can be used to detect the concentration of moisture in a concrete slab. There are many ways to test this. The fastest way is using a concrete moisture meter. Once the concrete is fully cured, (28 days post-pour) if the concrete moisture level is less than 4% consider using a penetrating sealer or acrylic sealer. Penetrating sealers will provide the best protection against water and salt intrusion but allow moisture vapor to travel through the sealer without failing. If the concrete moisture level is above 4% or 3lb/24hr/1000sf after taking a calcium chloride test, a moisture vapor barrier coating is the best option to stop moisture from coming up through a slab. It is the ideal product to use if you are going to be installing carpet, tile or wood flooring.
Weather, Temperature and Climate
Mother nature can be harsh on concrete, pavers, stone, and masonry surfaces. Even though it is known for being one of the toughest surfaces on the planet, concrete is made of natural elements that can fade, wear, dust, flake and breakdown over time. It may not seem necessary at first, but after a few years of exposure to harsh climates and weathering, concrete can start to show signs of wear.
Climate types can change the concrete in different ways. Northern climates experience large fluctuations in temperatures. This means concrete is expanding and contracting all the time. Driveways, roadways, garages, sidewalks, and walkways in northern climates are treated with salt, ice melt, and ice pre-treat chemicals. These chemicals wreak havoc inside concrete by attacking the reinforced steel, causing spalling, corrosion, dusting, and premature weakness.
If you live in a northern climate, look for concrete sealers that can protect against de-icing salts, freeze-thaw, and temperature fluctuations.
Best concrete sealer for northern climates:
In southern climates, look for concrete sealers that can withstand heat and UV rays. Other challenges in southern climates include, mold, mildew, humidity. Hot temperatures can make the application process tricky, so be sure to choose a sealer with a higher application temperature range. Common problems include bubbles, concrete off gassing, and white blushing; especially if the relative humidity is too high.
Best concrete sealer for southern climates:
Concrete Sealer Actives
Not all concrete sealer formulas are the same. Like medicine, a concrete sealer contains an active ingredient, which is made up the active substance itself. A carrier, vehicle, or liquid to which the active ingredient is carried, and any other materials that are inert.
Concrete sealer carriers:
- Water-based (water is the carrier)
- Solvent-based (solvent is the carrier)
- 100% active or solid (no carrier / otherwise known as “neat” or an “emulsion”).
Concrete sealer quality is primarily based on their substance type and active level (or amount). Higher levels of an active ingredient can greatly vary and can increase a concrete sealers’ ability to protect, long-term. Quality and type of solid or resin used in a film-forming coatings can provide big differences in performance level and price.
Concrete sealer ingredients:
- Penetrating sealers include: Silane, Siloxane, Silicate, Siliconate
- Epoxy coatings include: Bisphenol, Aliphatic, Novolac, Glycidylamine
- Urethane coatings include: Aromatic, Aliphatic
Indoor Concrete Sealer vs. Outdoor Concrete Sealer
Interior and exterior concrete sealers differ in numerous ways, but the main difference between indoor and outdoor coatings is in the resin type - the ingredient that binds and bonds the coating together. Exterior coatings feature softer resins designed to endure higher levels of moisture, ultra-violet exposure, and severe temperature fluctuations. Interior coatings tend to have a more rigid resins, which protect against scuffs, abrasions, and chemicals.
Good exterior concrete sealers include:
Good interior concrete sealers include:
It’s worth noting, that most exterior coatings are suitable for interior use. Conversely though, the same is not true for interior coatings - They can fail, yellow and delaminate quickly outside. Penetrating sealers and acrylic sealers can be used on both indoor concrete and outdoor concrete with no issues.
Frequently Asked Questions
What is concrete?
Concrete is a strong, dependable, versatile building material made from a mixture of aggregate (stone), Portland cement and water. When combined, it forms a fluid slurry that is easily poured and molded. It is an incredibility durable floor choice, especially when sealed properly. In fact, sealing concrete will extend the service-life up to 10x longer than concrete that is left unsealed.
Why do I need to seal concrete?
- To extend the service-life of concrete
- To add a decorative wet look or high gloss finish
- To prevent vapor moisture transmission
- To waterproof concrete
- To prevent de-icing salt & chloride intrusion
- To stop chemicals, staining and fluid penetration
- To prevent cracking and spalling
What concrete sealer should I use?
Decorative concrete floor sealers made from acrylic resins are a good choice for interior and exterior surfaces. They are affordable and versatile – making them the ideal choice for many residential surfaces where a wet look, high gloss or low gloss finish is desired.
Epoxy sealers, urethane coatings, and polyaspartic coatings are twice as durable as acrylics and are the preferred choice for surfaces with lots of foot traffic or heavy equipment. They are ideal for stopping chemical spills, oil and grease staining, and abrasions.
Penetrating sealers are most often used on surfaces that require friction, traction, or when a natural concrete finish is desired. Penetrating concrete sealers are excellent for waterproofing concrete and preventing deicing salt damage such as cracking and spalling.
What concrete sealer gets the best reviews?
Industrial or professional grade concrete sealers tend to receive the best reviews. It is very helpful to read reviews from customers who have used the concrete sealer you are interested in buying. Concrete sealer reviews add helpful application recommendations and tips.
Top reasons a concrete sealer receives a good review:
- Easy to apply
- Quality and amount of active ingredients
- Low odor (VOC level)
- Quick dry time
- Good coverage rate
- Water beading (hydrophobicity)
- Service life
Should I use a solvent-based sealer or a water-based sealer?
Typically, solvent-based sealers can provide longer-lasting protection because chemical solvents are able to penetrate deeper and react more evenly with the concrete.
- Solvent-based coatings are less susceptible to temperature and humidity, allowing them to dry quicker. This translates into a more stable environment for better reaction with itself and the substrate.
- When a solvent-based coating is curing, the active ingredients can bond together in a much tighter pattern and absorb deeper into the substrate. This leads to a stronger, more durable bond with the concrete. Plus, it creates a denser coating that is less likely to break down when exposed to water, salt, rain, and snow.
Water-based sealers on the other hand are solvent-free, environmentally friendly, and are a more cost-effective alternative to solvent-based sealers. Once of the major advantages of waterborne coatings is the absence (or lower) Volatile Organic Compounds (VOC’s). When working in a confined or poorly ventilated space, the evaporation of solvents can have a strong odor and may be considered hazardous to your health. For this reason, national, state, and local governments often regulate VOC’s by limiting how much odor a sealer can omit based on volume.
Will concrete sealer change the look of my concrete?
The primary reason for sealing concrete is to protect the surface. However, the concrete sealer you choose will play a significant role in the appearance of the concrete once the sealer cures. Most film-forming coatings like acrylic sealers and epoxy floor coatings will change the surface and enhance the color or gloss of the concrete. They can even add color. Penetrating concrete sealers work beneath the surface and do not change the appearance or texture of the concrete, pavers, or stone.
Sealers that change the surface (provide a “wet look” or enhanced look):
- Acrylic sealers
- Epoxy, Urethane and Polyaspartic coatings
Sealers that will not change the surface (provide an unchanged, clear, “natural” look):
- Water Repellents (Siliconate, Silicate)
- Water & Salt Repellents (Silane/Siloxane)
- Water, Salt and Oil Repellents (Silane/Siloxane/Fluorocarbon)
- Concrete Densifiers (Sodium Silicate, Lithium Silicate)
How much concrete sealer do I need?
To determine the correct amount of sealer, you must know:
- Square footage
- Coverage rate
Some concrete sealers will require multiple coats to provide adequate protection. Be sure to read the instructions and do not forget to multiply your square foot measurement with each coat.
Porosity of the concrete may impact coverage rate. Concrete that has a smooth, power troweled surface in general, will absorb less concrete sealer than a broom finished or exposed aggregate surface. Also, second coats tend to cover 20-30% more than the first coat.
Can you put concrete sealer on old concrete?
When applying a new concrete sealer to old concrete, it’s very important you make sure the old concrete sealer was removed or worn away. Old concrete sealer left on the surface of your concrete can impede the effectiveness of the newly applied concrete sealant in many ways:
- Old concrete sealer can prevent proper bond and adhesion of the new concrete sealer to the concrete surface.
- Old concrete sealer can also prevent new concrete sealer from absorbing into the concrete where it undergoes a necessary reaction with the concrete material.
- Old concrete sealer can be visually unappealing.
Removing old concrete sealer can be done in one of two ways: mechanical removal or chemical removal. Mechanical removal involves using a tool or machine to physically grind, sand, or blast away the previous concrete sealer. Chemical removal involves using a chemical or acid to strip away the previous concrete sealer.
Types of machines or tools used to remove old concrete sealer:
- Grinding wheel, diamond wheel, sanding pole, floor scraper
Types of chemicals used to remove old concrete sealer:
- Xylene, paint strippers, acids, alcohols, citrus-based strippers
How do I apply concrete sealer?
Applying concrete and paver sealer is easy and straight-forward. When applying a penetrating sealer, the most common method is a low-pressure garden pump sprayer. You can also use a paint brush or roller, but spraying concrete sealer is as simple as spraying your foundation for insects. Film-forming coatings like epoxies, urethanes, or acrylics can be applied like house paint, using a roller or brush.
- If concrete is “green,” new, or freshly poured, wait 28 days for it to fully cure
- Make sure concrete is clean and dry
- If applying a film-forming coating, ensure the concrete surface has a rough surface profile. Concrete Surface Profile Level 3 (CSP3) or greater is recommended for most concrete coatings.
- Check the weather and ensure no rain is in the forecast
- For water-based sealers, temperatures should be above 45 degrees F.
- If applying two coats, apply in thin layers – “Thin is in”
- Roll, spray, or brush in the same direction to reduce roller marks, streaks or gaps in coverage.
How long does it take for concrete sealer to dry?
Sealing concrete can be a quick and easy process that takes only a few hours to complete. Concrete sealers that require one coat usually dry within a few hours. Epoxies, urethanes, and acrylic coatings that require two coats will have a recommended time for recoat. However, penetrating sealers that require two coats should be applied wet-on-wet; which means you apply the second coat immediately after the first coat.
- Epoxy coatings and urethane coatings cure within 1-7 days
- Polyaspartic coatings cure within 6-24 hours
- Penetrating sealers cure within 2-12 hours
- Acrylic decorative coatings cure within 1-6 hours
- Silicate densifiers dry within 2-12 hours and fully cure within 5-7 days. Silicate densifiers work differently than traditional concrete sealers. Silicates continue to react with the calcium carbonate present in the concrete material as it forms small crystalline structures for up to 7 days. For this reason, it is recommended you wait the full 7 days before applying any top-coat sealer.
How often do I need to reseal concrete?
The answer is dependent on which concrete sealer is used. Some concrete sealers can last over ten years. Other concrete sealers are only expected to last two or three years. A concrete sealer that lasts longer but costs more may be a better long-term investment. Not only will it require less physical labor - since you will not be applying it every year, but it will provide better protection.
Exposure, climate, active ingredients, application technique, and quality of resin can also play a role in the service-life of a sealer. Foot traffic and thickness can also vary outcomes.
In general, concrete sealers will last:
- Silicates (lifetime)
- Silane/Siloxanes (3-15 years)
- Siliconates (3-10 years)
- Epoxy Sealers / Urethane Sealers (5-10 years)
- Acrylic Coatings (1-5 years)
How will you know when to recoat concrete?
When the concrete sealer or concrete coating looks worn, or you are unhappy with how it looks, it’s time for a recoat. All previously coated surfaces should be thoroughly cleaned before applying a new coat of material. Acrylic coatings are the easiest to recoat and usually do not require any preparation beyond a good cleaning. Urethane coatings and epoxy floor coatings require a light to medium sanding before reapplying. If the original coating is peeling, flaking, or delaminating, the previous coating will need to be removed. Fix the issue causing the separation before applying a new coating. Separation is usually caused by moisture or contamination beneath the coating.
When to recoat concrete coatings:
- If the concrete coating looks worn
- If the concrete coating is separating
- If the concrete coating is peeling or flaking
- If harsh chemicals have weakened the concrete coating
- If the concrete coating is turning yellow
How will you know when to reseal concrete?
Penetrating sealers (Silanes, Siloxanes, and Siliconates) will need to be resealed when the concrete, paver or masonry surface begins absorbing water again. A quick and easy way to check water absorption is by pouring a small amount of water onto the surface. Let the water sit for 5-10 minutes. If the concrete has darkened and absorped the water it is time to reseal. If the water is beading or still sits on the surface you do not need to reseal.
When to recoat concrete sealers:
- If water starts to absorb or darken the concrete
- If the concrete begins spalling or cracking
Concrete Sealer Problems and Fixes
Concrete Coating Problems and Fixes
There are five main reasons a film-forming concrete coating like an epoxy, urethane or acrylic will chip, peel, fail or delaminate.
- Too much moisture in the concrete
- Poor surface preparation
- Contamination on (or below) the surface
- Weak concrete
- Poor quality concrete sealer
Following good application techniques and best practices, you can avoid most concrete sealer problems. There can be many unforeseen challenges, as with any project, but surface preparation and planning are key to having the most successful outcome.
Acrylic Sealer Problems and Fixes
Scratching/Scuffing: In order to prevent scratching on an interior application, use a floor wax for an additional wear layer of protection. In order to fix existing scratching, wipe Xylene on the area and reapply an extremely light new coat of concrete sealer.
Blotchy and Dark Concrete: Blotchy concrete can result from over application. In order to prevent over application, apply sealers in thin, even coats. If over application does occur, use Xylene to correct the problem.
Water Spots: If water dries on a concrete surface that has been sealed with a concrete sealer it will dry with water droplet marks from the minerals in the water. In order to prevent this from happening avoid sealing in an area where water sprinklers constantly spray. If water spots do occur, squeegee the water dry where hard water dwells on the concrete.
Roller Marks/Streaks: Roller marks or streak marks occur when the sealer was applied too heavily, unevenly, or without maintaining a wet edge. Apply thin, even coats and if roller marks occur use Xylene to correct the problem.
Dried Milky White / Blushing:
Water-Based: During application if there is too much or too little humidity this can affect the appearance of the sealer. If the polymers of the sealer evaporate before the water, the sealed surface will turn a powdery white since the particles did not have ample time to come together before drying. In order to prevent this from happening try to seal with relative humidity below 85% a have a substrate that is 5 degrees above the dew point.
- Solvent-Based: When a solvent based sealer turns white it is known as blushing. There are two primary causes of blushing. The first of which occurs when applying a solvent based sealer to a substrate that is wet or green and can result in the sealers inability to bond to the concrete. Instead the sealer will be stuck on a film of water. The second which occurs when a solvent based sealer is over applied or when consecutive layers of sealer are frequently applied and never removed. The thick coats of sealer can cause moisture to be trapped under the sealer leading to delamination. In order to prevent this from happening apply sealer in thin, even coats instead of one heavy application.
Peeling/Flaking: Concrete sealers peel and flake when first applied if the application was too heavily applied or there are too many layers of sealer on top of each other. Delamination can commonly occur near the end of the lifespan of a sealer especially in high traffic areas or areas of direct sunlight. In order to prevent peeling and flaking of a new sealer make sure to wait until the previous sealer has worn away before applying a new layer of concrete sealer. If peeling or flaking is occurring prematurely use Xylene to correct the problem and re-solidify the concrete sealer.
Bubbling: Concrete sealers bubble when the application was too heavily applied or when a sealer has been applied in direct sunlight. In order to prevent this from happening apply two thin coats of sealer instead of one heavy coat. Two thin coats are much better than one, thick, heavy coat. The first coat acts like a primer and the second coat will add the even, glossy, color enhancing finish. Also make sure to apply sealer in the early morning or late evening when the temperatures are cooler. If bubbling does occur use Xylene to correct the problem and get rid of the bubbling. Do not apply another coat of sealer thinking this would rectify the issue; it will result in solvent entrapment.
Penetrating Sealer Problems and Fixes
Cracks, Pitting, Spalling: Cracks, pits, and spalls can happen for many reasons. However, they are generally caused where concrete is exposed freeze-thaw cycles. Rain, snow, and water are deposited onto a concrete driveway, concrete walkway or garage floor. The concrete then absorbs the water into its pores and capillaries. When this water freezes, it expands beyond the concretes ability to contain the mass of the ice, causing microscopic damage to the surrounding concrete. The best way to avoid this type of damage is to apply a penetrating concrete sealer that prevents the absorption of water, snow, and moisture into the concrete.
If you have concrete damage already you can rectify it by: