Introduction
Seal brick safely means choosing between breathable sealers and film coatings to protect the brick while allowing moisture to escape.
Breathable sealers let moisture pass through slowly, while film coatings form a surface layer. This article compares how they work and when each is a better fit for DIY projects.
For each type, follow manufacturer instructions and check labels for surface prep, cure times, and safety. Breathable sealers are easier to recoat and good for damp or porous brick, but they may require more frequent maintenance. Film coatings can give a stronger surface and deeper color but may peel if moisture is trapped or applied poorly; assess your brick condition and climate.
Key takeaways
- Breathable sealers penetrate brick; film coatings form surface barriers that regulate moisture.
- Assess brick condition and moisture before choosing; plan resealing intervals accordingly.
- Apply breathable sealers with thorough brushing or spraying on dry brick.
- Film coatings require clean, dry surfaces and even, thin coats.
- Expect different maintenance: breathable sealers renew less often than coatings.
- Safety: protect adjacent plants and use ventilation; avoid exposing stored finishes.
Table of Contents
- Introduction
- Key takeaways
- Quick Comparison: Breathable (Penetrating) Vs Film-Forming Sealers
- How Brick Works and Why Breathability Matters
- Properties of Breathable (Penetrating) Sealers
- Properties of Film-Forming Sealers (Coatings)
- Planning and Surface Assessment Before Sealing
- Application Process: Step-by-Step for Breathable Sealers and Film Coatings
- Maintenance, Inspection, and Reapplication Planning
- Safety, Environmental Impact, and Regulations
- Conclusion
- FAQ
Quick Comparison: Breathable (Penetrating) Vs Film-Forming Sealers
Breathable sealers penetrate the brick surface and allow moisture in vapor form to escape. Film-forming sealers create a surface layer that blocks some moisture movement. Each type trades off ventilation, stain resistance, and appearance differently.
Key decision factors include substrate type, environment, maintenance goals, and anticipated use. Choose breathable options when moisture management is a priority; opt for film coatings when a strong surface barrier and color enhancement are desired. Always verify prep needs, compatibility, and follow-up maintenance in the product instructions and labeling.
Quick pros and cons
Here’s a quick rundown of the main advantages and drawbacks for each type of sealer to help you decide which one suits your needs.
Pros: Breathable (Penetrating) Sealers
- Allows moisture vapor to escape, preventing buildup and efflorescence.
- Preserves the natural look of brick and masonry.
- Easy to apply and reapply as needed.
- Offers good protection against water intrusion.
Cons: Breathable (Penetrating) Sealers
- Does not provide stain resistance; dirt can still penetrate the surface.
- May not be suitable for high-traffic areas due to reduced durability.
- Requires regular reapplication, typically every 3-5 years.
Choose breathable sealers if you prioritize moisture management and want to maintain the natural appearance of your brick or masonry.
Pros: Film-Forming Sealers
- Provides excellent stain resistance, protecting against dirt, grease, and other contaminants.
- Offers a durable surface barrier, suitable for high-traffic areas.
- Available in various colors and finishes to enhance the appearance of your brick or masonry.
- Can be applied over existing paint or coatings without removing them.
Cons: Film-Forming Sealers
- Creates a barrier that prevents moisture vapor from escaping, potentially leading to trapped moisture and mold growth if not properly managed.
- Can make surfaces feel slippery when wet, posing a safety hazard in some areas.
- Requires more effort to clean and maintain than breathable sealers.
- May not be suitable for historic or heritage brick due to its altering effect on the surface’s appearance.
Choose film-forming sealers if you need strong stain resistance, durability, and are willing to trade off some breathability and maintenance ease.
Fast decision scenarios
Here are a few common scenarios that can help guide your decision on which sealer type to choose:
Historic or Heritage Brick: If you’re working with historic or heritage brick, it’s best to lean towards breathable sealers. These will help preserve the natural look and character of the brick while still providing protection against water intrusion.
Driveway or Walkway: For high-traffic areas like driveways or walkways, film-forming sealers are typically the better choice. They offer excellent durability and stain resistance, making them well-suited for these demanding environments.
Pool Coping or Outdoor Kitchen: In areas exposed to salt, chemicals, or frequent cleaning (like pool coping or outdoor kitchens), film-forming sealers can provide the necessary protection against staining. However, ensure proper ventilation and moisture management to prevent trapped moisture issues.
How Brick Works and Why Breathability Matters
Brick is porous and interacts with moisture through capillary rise, lateral movement, and vapor diffusion. Understanding these paths helps explain why breathable options matter. Non-breathable coatings can trap moisture and worsen damage over time.
Breathable sealers permit evaporation while film coatings tend to confine moisture. Look for signs like damp interiors, efflorescence, or spalling to gauge whether breathability is appropriate. Refer to product guides for specific brick compatibility and testing tips.
Brick porosity and moisture risks
Clay bricks are porous, meaning they’re full of tiny holes. This lets moisture move through them in three ways:
Capillary rise: Moisture from the ground seeps up into the brick like a wick.
Lateral movement: Water can spread sideways within the brick, especially when it’s wet.
Vapor diffusion: Even when bricks are dry, water vapor can pass through them and condense on cooler surfaces.
When non-breathable coatings cause harm
Film-forming coatings seal the brick’s surface tight. This traps moisture inside, leading to problems:
Blistering: Trapped water causes paint or coating to peel and bubble.
Efflorescence: Salt deposits form on the surface as trapped moisture evaporates, leaving a white, chalky residue.
Freeze-thaw damage: When water inside the brick freezes and expands, it can crack or spall the masonry. This is why non-breathable coatings are best avoided in cold climates.
Properties of Breathable (Penetrating) Sealers
Penetrating sealers differ from films by allowing water vapor to pass through the brick. This helps manage moisture and supports brick longevity. Breathable sealers are typically chosen to preserve a natural look while reducing staining potential.
Chemical families include silanes, siloxanes, silicates, and blends. Each family offers a mix of surface repellency, vapor permeability, and durability. Plan for proper prep, expected depth of penetration, and how porosity affects performance.
Performance characteristics
Breathable sealers work by penetrating into the brick’s pores, reacting with the masonry to form a protective barrier. Here’s what they do:
Water Repellency: They repel water from the surface while still allowing moisture trapped inside the brick to escape.
Vapor Permeability: This breathability prevents moisture buildup, which can lead to efflorescence and damage over time. It’s crucial for brick longevity.
UV and Freeze-Thaw Resistance: They protect against UV degradation and help prevent damage from freeze-thaw cycles, ensuring long-term durability.
Limitations and compatibility
While breathable sealers are great, they’re not perfect. Here’s when they might not work as expected:
Sealers may struggle on very dense or coated surfaces where penetration is limited. Always test a small area first.
Compatibility with Lime-based Mortars: Some sealers can react with lime in mortars, causing discoloration or damage. Check compatibility before use.
Regularly inspect your brickwork after sealing to ensure the sealer is performing as expected and no issues have arisen over time.
Properties of Film-Forming Sealers (Coatings)
Film-forming sealers create a continuous outer layer on brick surfaces. Common types include acrylics, urethanes, and epoxies. They can change appearance with gloss and color, and they provide surface-level protection.
Film formers carry risks like moisture entrapment around the barrier and potential effects on mortar integrity. Prepare the surface thoroughly, follow coat thickness guidance, and consider future restoration needs before choosing this option.
Aesthetic and protective benefits
Film-forming sealers create a continuous outer layer on brick surfaces, altering their appearance and enhancing protection. They come in various types:
Acrylics offer matte to semi-gloss finishes, urethanes provide high gloss, and epoxies have a tough, durable finish. Expect some color enhancement and increased stain resistance.
These sealers harden the surface, making it more resistant to water penetration and physical impact. However, they can slightly alter the natural texture of the brick.
Risks and failure modes
While film-forming sealers offer protection, they also pose risks if not applied correctly. Moisture can become trapped within the brick, leading to:
Efflorescence: a white, powdery deposit that forms when moisture meets unsealed areas. Spalling or peeling may occur if moisture buildup causes bricks to delaminate or mortar to weaken.
Film coatings should be avoided on historic or porous bricks, and in areas with high humidity or frequent temperature changes. Always ensure proper surface preparation and substrate compatibility to minimize risks.
Planning and Surface Assessment Before Sealing
Define the sealing objective and how breathability will influence results. Proper prep sets the stage for long-term performance. Skipping steps invites premature wear or uneven appearance.
Moisture testing, efflorescence removal, and existing coating checks are essential. Document findings and plan patch testing to validate adhesion and performance. Use the results to decide breathable versus film options and sequencing.
Tools and materials checklist
Before you start, make sure you’ve got everything you need. This list will help you gather the right tools and testing materials.
- Moisture meter: To check moisture levels in your bricks. Skipping this can lead to improper sealing or even damage from trapped moisture.
- Efflorescence cleaner: To remove mineral deposits that could affect adhesion and finish.
- Stiff-bristled brush: For scrubbing surfaces clean before sealing.
- Sprayers or paintbrushes: Depending on your chosen sealer, you’ll need the right applicator. Check product datasheets for recommendations.
- Tape measure: To mark out test patches and ensure even application.
- Drop cloths or plastic sheets: To protect surrounding areas during testing and sealing.
- Safety gear: Include gloves, goggles, and a respirator for protection against chemicals.
- Sealer samples: Buy small quantities of your chosen sealers to test on patches first. This helps avoid costly mistakes.
Quick rule: Always check product datasheets for specific equipment recommendations and safety guidelines.
Compatibility and small test patch
Before sealing your entire brick surface, it’s crucial to test your chosen sealer on a small, inconspicuous area. This helps ensure compatibility and allows you to observe the results over time.
First, select an area that’s representative of your project – same exposure, age, and condition. Then, apply the sealer according to the manufacturer’s instructions. Use a sprayer or paintbrush for even application.
Next, wait 48-72 hours to observe the results. Look for any signs of poor adhesion, discoloration, or other issues. Also, check product datasheets for specific observation periods and guidelines.
Remember: If you’re unsure about compatibility or have concerns about your bricks’ condition, consult a professional before proceeding with full-scale sealing.
Application Process: Step-by-Step for Breathable Sealers and Film Coatings
Prepare with parallel workflows for breathable and film coatings, focusing on cleaning, drying, and weather checks. Both paths require a clean, sound brick surface and absence of active moisture. Align your plan with the chosen sealer type before starting.
Apply by the recommended method for each type: breathable sealers often use light, even applications; film coatings require uniform coats and careful back-brushing or rolling. Pay attention to tack-free times, curing conditions, and any recoat windows specified on the label.
Step-by-Step Process
The following steps guide you through the application process for both breathable sealers and film coatings on brickwork, ensuring a safe and effective outcome.
- Preparation: Ensure the surface is clean, dry, and free of efflorescence. Check weather conditions and allow sufficient drying time before starting.
- Safety Checks: Wear appropriate PPE, including gloves, goggles, and a respirator if needed. Conduct a small patch test to ensure compatibility with the brick and sealer.
- Breathable Sealer Application: Apply thin coats using a low-odor, penetrating sealer via spray or brush. Immediately wipe off any excess to prevent streaking.
- Film Coating Application: Apply even coats with a roller, brush, or sprayer, ensuring no pooling occurs. Follow the recommended coverage rates and interim recoat intervals.
- Drying and Curing: Allow the sealer to dry and cure according to the manufacturer’s guidelines, considering temperature and humidity ranges, and providing adequate ventilation.
- Final Checks: Inspect the sealed surface for any signs of streaking, whitening, or uneven absorption. Address any issues promptly to prevent further problems.
- Cleanup: Clean tools thoroughly with water (for water-based sealers) or appropriate solvents (for oil-based sealers).
Applying penetrating sealers
Penetrating sealers, also known as breathable sealers, are applied to protect brickwork while allowing moisture vapor transmission. Here’s how to apply them effectively:
Surface Preparation: Clean the surface thoroughly using a suitable cleaner or water and a stiff brush. Remove any efflorescence with a solution of muriatic acid (follow safety guidelines).
Application: Apply the sealer using a low-pressure sprayer or roller, ensuring even coverage. Work in small sections to avoid over-application or ponding. For concentrated sealers, dilute according to the manufacturer’s instructions.
Avoid Over-Application: Be mindful not to apply too much sealer, as this can lead to streaking and ghosting effects. Wipe off any excess immediately after application.
Applying film-forming coatings
Film-forming coatings provide a protective barrier on brickwork, preventing moisture ingress while allowing water vapor to escape. Here’s how to apply them correctly:
Surface Preparation: Ensure the surface is clean, dry, and free of contaminants. Remove any efflorescence using a suitable cleaner or muriatic acid solution.
Priming and Application: Apply a primer coat if recommended by the manufacturer to improve adhesion and seal the surface. Allow it to dry according to the product’s guidelines. Apply film-forming coatings using a roller, brush, or sprayer, ensuring even coverage without pooling. Follow the recommended number of coats and interim recoat intervals.
Temperature and Humidity Considerations: Apply film-forming coatings within the recommended temperature and humidity ranges for optimal performance. Consult product data sheets for exact cure times and follow safety guidelines during application and curing.
Maintenance, Inspection, and Reapplication Planning
Set a cadence for inspections that suits the climate and exposure. Use non-destructive cleaning and document wear or changes in appearance. Keep a simple log to track issues and actions taken.
Define clear criteria for reapplication or repairs, like noticeable wear or compromised film, and plan repairs before resealing. Record the condition, testing results, and any weather delays to guide future decisions.
How to tell a sealer is failing
Regularly inspect your sealed brickwork to catch any issues early. Here’s a simple checklist.
- Water Beading: Check if water forms beads on the surface. If it doesn’t, the sealer may be compromised.
- Staining: Look for stains or discoloration. This could indicate that the sealer is no longer repelling moisture.
- Film Peeling: Check if any of the sealant film is peeling off. If so, reapplication may be needed.
- Dampness: Feel for dampness on the brick surface. Excessive moisture can cause damage over time.
- Efflorescence: Look for white, powdery deposits. This could indicate that moisture is being trapped behind the sealer.
- Wear Patterns: Inspect areas with heavy foot traffic or exposure to elements. Uneven wear may indicate a need for reapplication.
- Cracking or Spalling: Check for cracks in the brick or mortar, or pieces flaking off (spalling). These issues must be repaired before resealing.
- Mortar Gaps: Inspect mortar joints for gaps. If present, they should be repointed before resealing.
Quick rule: Don’t wait until you see major damage. Regular inspections help catch issues early.
Long-term cost and life-cycle considerations
Understanding the long-term costs of each sealer type helps you plan your maintenance budget.
- Breathable Sealers: These typically need reapplication every 5-10 years. They’re cheaper initially but may require more frequent reapplications.
- Film Coatings: These usually last longer, up to 20 years or more. However, they can be more expensive and may require professional application.
- Climate Influence: Harsh weather conditions can shorten the lifespan of both types. Consider your local climate when estimating service intervals.
- Product Warranty: Check the warranty period for each sealer type. This gives you an idea of how long it should last with proper maintenance.
Quick rule: While breathable sealers may seem cheaper initially, film coatings could save you money in the long run due to their longer lifespan.
Safety, Environmental Impact, and Regulations
Wear appropriate PPE, ensure ventilation, and avoid confined spaces during application. Protect yourself from splashes and fumes, especially in enclosed areas. Monitor temperature and humidity for safe work条件.
Check product labels and SDS for VOC information and disposal rules. Consider local regulations and environmental impact when choosing breathable versus film options. Use these references to guide safe, compliant selections and workflows.
DIY Safety Checklist
Before you start sealing your bricks, go through this checklist to ensure a safe and successful job.
- Protective Clothing: Wear long sleeves, pants, and closed-toe shoes. Why? To protect your skin from chemicals and debris.
- Gloves: Use chemical-resistant gloves. Why? To prevent skin irritation or burns.
- Eye Protection: Wear safety glasses with side shields. Why? To protect your eyes from splashes and debris.
- Respirator/Mask: Use a respirator or proper mask for the sealer’s VOC content. Why? To prevent inhalation of harmful fumes.
- Ventilation: Ensure adequate ventilation, avoid confined spaces, and use fans if needed. Why? To reduce exposure to fumes and ensure proper drying.
- Work Area Containment: Cover nearby surfaces with drop cloths or plastic sheets. Why? To prevent accidental spills from damaging other areas.
- Spill Response: Have rags and absorbents ready to clean up any spills. Why? To prevent slips, stains, and environmental damage.
- Avoid Extreme Temperatures: Do not seal in extreme heat or cold. Why? It can affect the sealer’s performance and your safety.
Quick rule: Always follow manufacturer guidelines for specific product safety measures.
Environmental and Health Considerations
Understanding the environmental impact and health considerations of sealers is crucial for responsible DIY work.
VOCs: Volatile Organic Compounds are emitted by some sealers. Breathable sealers typically have lower VOC emissions than film coatings. Why? They penetrate rather than sit on the surface, reducing off-gassing.
Choose low-VOC or water-based options to minimize health risks and environmental impact. Always check the Safety Data Sheet (SDS) and product data sheets for VOC content and emissions information.
Runoff and Storm Drains: Do not let sealers enter storm drains or run off into the environment. Why? They can contaminate water sources and harm wildlife. Clean up any spills immediately, and dispose of leftover sealer and containers according to local regulations.
Sensitive Sites: Be extra cautious when sealing near water bodies, gardens, or other sensitive areas. Why? Sealers can harm plants and aquatic life if they come into contact with them. Use appropriate containment measures and consider using eco-friendly, low-impact sealers.
Conclusion
Choosing the right sealer matters for safety, durability, and how your brick looks in years to come. A breathable penetrating sealer keeps moisture moving and reduces damage, while a film coating can guard surfaces that tolerate occasional wet conditions but can trap moisture if misused.
Start by checking the surface: clean and dry it, test a small area with your chosen product, compare how it goes on and dries, then plan a simple two-step approach: decide on breathable or film, patch any damaged joints if needed, and apply in thin, even coats following the label. Read and follow the manufacturer’s instructions, work in good light and dry weather, wait for the material to cure, and routinely inspect and schedule maintenance as needed.
Common mistakes to avoid are applying sealers to damp brick, using the wrong type for the environment, and rushing the cure. Safety rules are simple: use eye protection and gloves, keep good ventilation, test first, and never seal a brick you suspect is still moisture-laden or damaged. If the job would require cutting corners or changing weather expectations, or if you have a historic or heavily damaged wall, call a professional for a proper assessment and treatment plan, and stay focused on steady, deliberate work—you’ll protect the brick and your investment. Stay practical, and you’ll seal it right the first time.
FAQ
When should I choose a breathable penetrating sealer versus a film-coating sealer for brick?
Breathable sealers are best when you want the brick to dry out and release moisture. Film coatings are for when you need a visible protective layer and easier cleaning on the surface.
What are the main differences in the application steps for each type?
Breathable sealers are usually applied in thin coats with brushes or rollers and can require longer cure times. Film coatings go on as a uniform surface layer and may require surface prep and curing according to the product label.
What are the key drawbacks or risks of each sealer type?
Breathable sealers can wear off unevenly and may not repel heavy staining as strongly. Film coatings can trap moisture if not breathable, peel, or show surface wear over time.
How should I maintain and re-seal brick after application?
Inspect for wear or staining periodically and follow the product’s reapplication guidelines. Always clean the surface first and verify compatibility with prior coatings before applying anything new.