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How to Utilize a Clear Sealer on Chimneys and the Best Option Available

How to Utilize a Clear Sealer on Chimneys and the Best Option Available


The materials used to construct a chimney are numerous. The outer layer is masonry (bricks and mortar) with an inner liner frequently made of fire-resistant metal. 

Maintaining your chimney in excellent working condition requires regular maintenance, which for many homeowners means using a chimney sealant. Which type of sealer provides the most durable finish, while letting the beauty of the brick or stone shine through?

If you have a clear sealer on a chimney, it will protect your home from water damage and keep your property looking good for years to come. While there are many types of clear sealers available on the market, they are not all equal. Let us help you choose the best clear sealer for your chimney.

Why Seal a Chimney?

Maintaining your chimney is a job that must be done regularly, and it entails keeping moisture out. The bricks in your masonry chimney will deteriorate faster if rain, humidity and condensation get inside. This is because the freeze/​thaw cycle causes the masonry to decay.

Water expands the pores in a brick as it freezes. When the water thaws and evaporates, there is more room for water to fill the next time. This cycle repeats throughout the winter months until the bricks’ structural integrity is lost, causing fissures and eventually detaching entirely. This would mean more damage to repair the longer you wait to seal your chimney. To fix cracks and fissures, you would need to utilize masonry crack fillers, such as these by DRYLOK, to fix any damage before you can waterproof your chimney.

Even if you live in an area that rarely experiences a freeze/​thaw cycle, preventing moisture from penetrating the brick or stone of your chimney is still necessary. Mold thrives in dark, damp and isolated places. Unfortunately, your chimney might be one of those locations. 

Mold can cause various health problems for people. Asthma and allergies are associated with mold growth, as well as more serious illnesses like respiratory infections and lung disease. Aside from that, mold can damage your chimney and necessitate costly repairs! Mold can be easily avoided by properly sealing your chimney.

Protect from Moisture

Clear sealers are designed to create an invisible barrier between the masonry and the outside elements. This barrier will prevent water from seeping into the pores of the masonry, which can cause cracks and other damage. A clear sealer will also protect your chimney from the damaging effects of UV rays, as well as pollutants and other debris that might be in the air.

Retain Aesthetic for Long Term

Clear sealers are also effective at repelling stains, which can make your chimney look dirty and unattractive. The right clear sealer will help your chimney maintain its aesthetic appeal for years to come. 

The Best Sealer for Chimneys: DRYLOK® Siloxane 7

The Best Sealer for Chimneys: DRYLOK® Siloxane 7


DRYLOK Siloxane 7 Brick & Masonry Penetrating Sealer is a one-coat, weatherproof treatment made with a 7% silane/​siloxane blend. This unique combination delivers superior performance and protection against staining, efflorescence, freeze/​thaw cycles and hurricane-force, wind-driven rain. It builds a lasting barrier against moisture by going through the substrate without forming a film or altering the look or feel of the surface. Some benefits include: 

  • A breather-type finish that keeps water droplets out but allows water vapor to escape

  • An estimated service life is more than 10 years

  • Excellent freeze-thaw protection, prevent salt deterioration and are widely used in commercial and residential projects as water repellents and waterproofers, especially on porous cement substrates like cinder blocks, stucco, brick and concrete

  • Sealer products are VOC standard compliant 

  • It does not yellow over time

To learn more about why DRYLOK® Siloxane 7 Brick & Masonry Penetrating Sealer is different from most sealers, visit our videos section on dry​lok​.com.

Make Sure to Properly Prepare and Seal the Chimney

Follow these simple steps to ensure the best results when applying the clear sealer to your chimney.

1. Check for Any Cracks to Fill With Masonry Crack Filler

Check for Any Cracks to Fill With Masonry Crack Filler


DRYLOK® Masonry Crack Filler seals, waterproofs and repairs cracks and masonry joints in chimneys and other masonry surfaces. It hardens to the color of concrete after drying, has no bleeding effect on neighboring surfaces or materials when dry and cleans up quickly with just soap and water.

2. If Present, Remove Efflorescence

If Present, Remove Efflorescence


When water evaporates, efflorescence is a crystalline deposit of salts that forms on the surface of brick, stone, stucco, concrete or other construction materials. Its white or gray-tinted color and powdery texture distinguish it from other stains, as well as its sparkling consistency that sometimes glistens in the light. It needs to be removed before sealing the chimney.

DRYLOK® Powder Concrete and Masonry Etch & Cleaner prepares interior/​exterior masonry and concrete for waterproofing and painting.

  • Pre-wet the surface

  • Scrub and remove as much dirt, efflorescence and dust from the surface as possible using a steel brush

  • Wash and rinse each part carefully before continuing

  • Only treat areas where efflorescence is present if you’re treating the surface for efflorescence

3. Clean Off Any Remaining Debris

If there is still dirt, grime or other substances still clinging to the surface, use a detergent cleaner to remove them.

4. Allow Brick to Dry Before Sealing

Make sure the surface is completely dry before sealing. For optimum results, DRYLOK Siloxane 7 Brick & Masonry Penetrating Sealer should be applied following at least a two-day dry spell.

5. Apply DRYLOK Siloxane 7 Penetrating Sealer

When both air and surface temperatures are 50°F or higher, wait for a dry (rain-free) period. Do not thin the product. Overspray should be avoided on glass, wood surfaces and shrubbery. The most effective way to apply DRYLOK Siloxane 7 Brick & Masonry Penetrating Sealer is to spray it.

A garden sprayer or power equipment is sufficient. The best effects are obtained by removing most of the pressure from the gun or nozzle and operating with the lowest possible pressure in the spray tank. Hold the stream at a steep angle to prevent splashing beginning at the top of the wall and begin working your way down.

Try to achieve a run-down of 8 to 12 inches while spraying the chimney. You can use this method to create a uniform coating of material over the surface by continuously spraying with a steady stream. It’s critical to keep the gun or nozzle as close to the work as possible.

Extreme care must be exercised when DRYLOK Siloxane 7 Brick & Masonry Penetrating Sealer is applied with a brush to ensure uniform flooding of the surface. It’s best not to brush it out at all.

Rely on DRYLOK for All of Your Masonry Care and Repair Solutions

Looking for a reliable solution for all your masonry sealing needs? Depend on DRYLOK Masonry products for unbeatable quality and performance. From clear sealers to masonry crack filler, we have everything you need to keep your chimney and other masonry structures in top condition. Contact us today for more information and to find a retail outlet near you.