How to Fix Crumbling Stone with a Densifier Sealant That Actually Works

TSSPRO Sealants manufactures a densifier sealant that strengthens and protect natural stone suffering from erosion, chipping, pitting, flaking, or crumbling. This specialized product isn’t just another regular sealant. It penetrates deep into the stone, strengthening from within and stopping damage before it spreads. For contractors dealing with problematic pool coping, eroding limestone, fragile moss rock, or flaky sandstone, using a densifier is the first step to saving the stone and delivering lasting results.

You know the kind of job we’re talking about. You get to a home and the stone is breaking apart at the edges. It flakes by hand. The customer wants it fixed, but if you don’t start with the right prep, even the best sealer will fail. That’s where a densifier sealant like TSSPRO 650 can help.

Why Crumbling Happens in the First Place

Natural stone like flagstone, limestone, sandstone, and even certain types of concrete are porous and soft by nature. Over time, exposure to weather, moisture, pool chemicals, and foot traffic weakens the surface. Natural binding material within the stone can be lost from various forms of exposure.  The stone begins to flake or sand. Left untreated, this turns into serious surface loss—and eventually, expensive replacement.

Here’s How a Densifier Works

A densifier isn’t a protective coating. It chemically reacts with the stone’s internal structure to harden and strengthen it from the inside. TSSPRO 650 seeps into the pores of the stone and forms a denser, more stable internal matrix. That means:

• Less surface erosion

• No more powdering

• Reduced Flaking

• A stronger foundation if a film forming sealant is used later

Now the surface is ready for a protective sealant like TSSPRO 300 or TSSPRO 360, depending on the desired finish. Without densifying first, the substrate continues to fail and the previously applied sealant will be lost.

Let’s Walk Through the Process

This is what happens when you skip the densifier:
You seal the stone.
It looks great.
It flakes two weeks later.
You get the call.
You go back.
You explain what went wrong.

This is what happens when you use the densifier first:
You stabilize the stone.
You determine that the stone loss has stopped.
You apply the film forming sealer.
It bonds.
It holds.
It lasts.

And your customer? They call you again, but this time it’s for the next project.

Where to Use TSSPRO 650 Densifier

This product is designed for any surface showing signs of weakness. That includes:

• Aging limestone pool coping that’s pitted or chalky

• Flagstone walkways where material loss on the surface is evident

• Masonry walls where stone is eroding faster than the mortar

• Pool Water Features when sand accumulation is found at the bottom of the pool

Contractors working on projects with frequent water exposure will see more of these issues. The stone needs help. Densifiers are the best chance at giving the stone a second chance.

The Right Way to Apply It

Using TSSPRO 650 is simple, but timing and prep matter. Here’s a quick checklist:

1. Clean the surface. Remove dirt, mold, and previous coatings if present.

2. Let it dry. The densifier ONLY works on a dry surface so it can penetrate deeply.

3. Apply with a brush, a pump sprayer, or a roller. Apply “wet on wet”, allow the substrate to absorb as much as possible.

4. Let it cure for 24 hours before water exposure.

5. Test the surface. After 7 days monitor the conditions. If damage has subsided, it is ready for a film type sealant (optional).  If not, a subsequent application may be required.

Learn more about our high-quality sealants by calling today.

Can You Use a Sealer Without a Densifier?

Sure, but it won’t work well on damaged stone. A densifier is not optional when the surface is already compromised. It’s the foundation. Skip that step, and the finish will fail.

The Takeaway

TSSPRO Sealants makes densifier products like TSSPRO 650 that stabilize and strengthen soft, damaged stone before sealing. If you want your sealer to do its job right—and you want to avoid callbacks and failed coatings—this is the step you can’t skip.

The stone might look too far gone. But it might not be.
With the right prep, the right densifier, and the right team, you can bring it back—and keep it that way.

Have questions about densifiers or what to use on your next project? Give the experts at TSSPRO a call. We’ll help you choose the right solution so your work stays solid.