CoverSeal PEN 50 Water and Mold resistant Penetrating Sealer


Application Method: Pump-up Spray, Roller, Brush
Coverage: 200-260 sq.ft/gal. Two coats recommended
Dry Time: 45 mins
Dry time: Light Traffic 3 hrs Heavy traffic 24 hrs
Surface: Concrete, Clay Tile, Stucco, Pavers, Natural Stone, Brick, Splitface Block, Masonry.
Finish: Natural, no change in appearance
Base: Water Base, Zero odor


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CoverSeal PEN 50 Natural Dry-Look, Water-Based Penetrating Concrete Sealer

Prevents Cracking & Spalling. Mold And Mildew Resistant. Blocks Salt Damage From Chlorides.


What Is Coverseal Pen 50 Water And Mold Resistant Penetrating Sealer?

Coverseal Pen 50 sealer is a penetrating sealer. This means that it penetrates into the surface – concrete, stone, etc. – without leaving a film on the surface.

It’s very water resistant. It’s made from a blend of silanes and siloxanes that penetrate into the concrete.

These substances react to form a silicone resin that’s highly water resistant and highly repellent.

It does an excellent job of keeping water out of the concrete or stone, and it will protect it from mold growing.
It’ll protect it from salts getting into the surface from freeze-thaw attack.

You can use it in both interior and exterior applications, and it will protect your concrete or other porous surfaces.


Is Coverseal Pen 50 Penetrating Sealer A Commercial Product, Consumer Product Or Both?

Pen 50 is available both to the commercial customer and also the DIY consumer.

The product was developed initially for commercial applications. Situations like historic buildings, public walkways, etc.

But it is very user-friendly. It’s a water based product that is easy to use, and easy to apply.

With that said, it is definitely a professional-grade product we sell to commercial contractors, even though we make it available to the DIY market as well.


Every-Day Signs That Indicate You Need A Product Like Coverseal Pen 50.

Mold and Mildew:

If you’re seeing signs of mold and mildew on your concrete, natural stone, limestone – any kind of porous surface – that’s a good indication that you need a penetrating sealer. Something like the Coverseal Pen 50 product.

Crumbling or Dusting:

If you’ve got concrete and you’re noticing signs of crumbling or dusting, that’s probably because moisture has gotten into the surface.
With ongoing freeze-thaw action (as the water freezes and expands), it crumbles and cracks the surface.
If you’re seeing signs of that on concrete or pavers, this is another clear indication that you should be using something like the Pen 50.

Any porous surface can benefit from a penetrating sealer like Pen 50, and it will not change the look of your surface.

It doesn’t matter if it’s sandstone, limestone or natural stone and you don’t want to change the look but you want to protect it, Pen 50 is an excellent product for the situation.


Typical Situations Where Someone Would Use Coverseal Pen 50

Much of the time, our customers using Pen 50 are dealing with exterior situations.

Typically, they come to us describing situations where moisture got into surfaces, resulting in mold and mildew.   When this is the case, we usually recommend Coverseal Pen 50.

Other typical examples of where a penetrating sealer would be useful include natural stone like limestone or sandstone that is:

  • – In your patio
  • – Around your pool deck
  • – On brick walls
  • – On vertical surfaces like outdoor showers or artificial waterfalls.

Anywhere it can get damp, and you need to prevent that moisture getting into the surface, that would be an ideal application for Coverseal Pen 50.

And again, most customers love that they can use it, without it changing the appearance of their surfaces.  It does not darken the surface. It won’t give it a sheen. It’ll just keep that natural look.

Another reason customers love Coverseal Pen 50 is that it protects surfaces from what we call “freeze-thaw” attack.

Pen 50 easily repels that moisture from getting into the surface, and causing the crumbling and cracking of the surface.

Examples of exterior applications include:

  • – Driveways
  • – Patios
  • – Pool decks
  • – Etc.

Commercial applications include:

  • – Building entrance ways
  • – Public walkways
  • – The walls in warehouses and buildings
  • – Etc.

All of these surfaces need strong protection those from freeze-thaw attack.

Last of all, your surfaces need protection from chlorides.

If you’re using de-icing salts during the winter, they can be carried into the surface via the melting ice or snow.

Coverseal Pen 50 would provides a highly durable barrier against the moisture and anything in it.

It would repel those chloride chemicals from getting into your concrete or natural stone.


Why Does Coverseal Pen 50 Produce Better Real-World Results Than Store-Bought Sealers?

Coverseal Pen 50 is a very versatile penetrating sealer, and it’s unique formulation gives it 2 distinct advantages over the competition.

First of all, it contains a higher “active solids” content than competing brands. This means that it provides much higher repellance to moisture or other contaminants.
It also means that surfaces treated with it will be protected for a much longer period of time, compared to those sealed with a competing product.

Secondly, it works on multiple surface types.
The silane-siloxane blend that CoverTec has formulated works very well on:

  • – Concrete
  • – Natural stone
  • – Clay
  • – Brick.

Most competing products are formulated to work on a single surface type.

Basically, if you use a competitive product, you will lose repellance faster, and you’ll have to re-apply that product more often.


When Applying Coverseal Pen 50 To A Surface, What Are The Recommended Steps?

Using Pen 50 is very easy.  It’s a water based product.  It’s not hazardous.

However, the first step is making sure the surface is porous or absorbent.  Basically, the sealer must be able to soak into the surface rather than just sit on top of it.

You can test this by putting some water on the surface, and making sure it is fully absorbed.

You will need to clean off anything that may prevent the sealer from being absorbed into the surface pores.  Things like dirt, oils or debris will need to be removed as best as possible.

Obviously, if there is any mold or mildew present, you should clean that off before applying the product.

Assuming that the surface is clean and passes the water-absorption test, the next step is to apply the product using a pump-up sprayer.  That’s probably the most effective way of doing it.

Spray the product over the surface as evenly as possible. It should soak into the pores within 5 to 10 minutes.

If it hasn’t soaked in by that time, spread the product laying on the surface around or sweep it off into an area that hasn’t been sealed yet.

When it comes to coverage area, you’ll get around 150 to 250 square feet per gallon, depending on the porosity of your surface.

If your surface is very porous, it can take 2 coats.  Depending on the ambient temperature while applying the product, apply the 2nd coat at least 1 hour after the 1st coat.

If your surface is not very porous, you’ll notice the product will be slow to soak in.  In these cases, 1 coat should be sufficient.

We always recommend that you wait 4 hours before exposing it to any moisture or water.   After that, you’ll find it can be driven on or walked on, and be exposed to moisture.

You will be able to walk on the sealed surface within 1 to 2 hours, depending on the temperature.

The longer you let the Pen 50 sealer be absorbed into the surface pores, the more effective it will be.

In the background, the surface is going to continue to cure for the next 24 hours. As a result, you’ll experience maximum water-repellance after 24 hours.


How Does Coverseal Pen 50 Interact With 3rd Party Products Or Product Types?

We recommend being careful with how you use Pen 50 in combination with other products.

It’s a penetrating sealer, so it’s function is to soak into the surface.

Any other existing sealer, curing agent, bond breaker, etc. must be removed from the surface so that Pen 50 to penetrate it.

Once Pen 50 has sealed the surface, it’s function is to repel water – in particular – from getting into it.

You will not be able to add another sealer or coating on top of it.  Pen 50 will act as a bond breaker on the surface, and actually reject the 2nd sealer or coating.


We strongly recommend that once you use Pen 50, you should continue using it – whenever you need to.
As stated above, you won’t need to use as much as the store bought sealers because it lasts so long.

With that said, IF you decide to use another product over the top, you’ll need to remove the Pen 50 seal first.
You can simply etch off the seal prior to introducing the new solution you have chosen.


CoverSeal PEN 50 Case Study:

Here’s what Bob – a user of CoverSeal PEN 50 penetrating concrete sealer – had to say about it after applying it to a basement area for a customer of his.




  • Long term protective repellent layer
  • Prevents Cracking and Spalling
  • Water-resistant
  • Excellent penetration into porous substrates
  • Mold and mildew resistance
  • Blocks salt damage – chlorides
  • Breathable
  • Reduces water absorption
  • Reduces dirt pick up and staining
  • Retards efflorescence
  • Zero odor (low VOC)
  • Easy to apply

Typical Uses

  • Architectural Concrete
  • Concrete Block
  • Split-face Block
  • Roof Tiles
  • Porous and Dense Brick
  • Stucco
  • Exposed  aggregate concrete
  • Stone and Slate Tile
  • Pavers


Shelf Life

18 months when stored at 77°F (25°C) or less in a dry and shaded area.


Theoretical Coverage

260ft² per gallon (6.5m²/L) per coat.

Very porous substrates will require a two coat application or higher application rate.


Additional information


5 Gallon

Coatings & Sealers



Concrete Protection, Waterproofing/Water Repellent


Interior, Exterior




Pump-up Spray, Roller, Brush

Dry Time

Light Traffic 45 minutes Heavy Traffic 24 hours