Frequently asked questions.

Tile needs sufficient mortar contact underneath it. During installation, thinset mortar should be combed in straight, consistent ridges that collapse when the tile is properly bedded. Swirled or “rainbow” troweling, spot-bonding with blobs of mortar (“cookies”), incorrect mixing, or inadequate bedding can leave unsupported pockets beneath the tile.

Those voids can contribute to hollow sounds and cracking. However, grout and tile can also crack because of movement in the subfloor, moisture, or other installation problems. The cause should be identified before choosing a repair. Where the substrate is sound and the problem is suitable for injection, our self-leveling adhesive is designed to fill accessible voids without removing the entire floor.

No. Hollow sounds alone do not establish the cause or severity of a flooring problem. Injection may be appropriate for accessible voids beneath otherwise serviceable flooring, but it cannot correct a moving or damaged subfloor, ongoing water intrusion, inadequate movement joints, or structural deficiencies.

If tiles are extensively cracked, the floor is moving, or the cause is uncertain, have a qualified flooring professional assess the installation before proceeding.

Not necessarily. Our injection system is designed to deliver adhesive through small drilled openings and into suitable voids beneath existing flooring. This can help avoid removing and replacing an otherwise serviceable floor. Whether a particular floor can be repaired without replacement depends on its actual condition and the underlying cause of the problem.

Our USA-made, patent-pending Hollow/Loose Flooring Injection Tool is designed to deliver Stone Science adhesive beneath suitable hollow or loose flooring. The adhesive is formulated to flow into accessible voids, supporting a targeted approach to repair rather than immediately removing the existing installation.

The adhesive is designed to be strong yet flexible. Repair suitability and long-term results depend on the floor’s condition, preparation, and proper application. No injection system can correct an unstable substrate or every cause of grout or tile failure.

The system is intended for use with an airless paint sprayer. A model with a bucket holder is our preference because it is easier to maneuver, but that feature is not required. You can purchase or rent a suitable sprayer.

Before connecting the tool, confirm that the sprayer, hose, fittings, and fluid-contact components are compatible with the adhesive and tool. Follow the sprayer manufacturer’s operating, pressure-limit, and cleaning instructions. Do not assume every model or connection is compatible without checking.

With the adjustable depth collar installed, the needle reaches approximately 3/16 inch to 1 inch. Without the collar, maximum needle reach is approximately 1 1/4 inches.

The needle does not need to reach the very bottom of the void for every application. A deeper drilled opening may be required in some situations, but first confirm that drilling will not contact heating elements, plumbing, or other concealed services. Do not use the system on in-floor heating installations.

Purchase the Hollow/Loose Flooring Injection Tool and enough Stone Science adhesive for your project, plus a compatible airless paint sprayer. Have clean water, buckets for adhesive and flushing, paper towels, blue painter’s tape, and suitable safety equipment available. For larger projects, plan on extra 1/8-inch masonry drill bits.

Consult the current product listing for exactly what is included in your kit and our complete How to Use guide for setup, priming, injection, and cleanup instructions.

Yes. Excess pressure can lift or dislodge a tile. Drill suitable relief openings around the tile—typically near the corners and along the sides, provided it is safe to drill—and apply adhesive slowly at the lowest suitable sprayer setting. Stop immediately if the tile starts to lift or unexpected resistance develops.

For a loose tile, some installers use a carefully placed bucket of water as a temporary weight during curing. Only do so when the tile and substrate can safely support that weight, and follow the adhesive’s curing instructions. Never place your hands near a pressurized needle or leak: high-pressure fluid injection is a medical emergency.

No—we do not recommend using the system on floors with in-floor heating. Drilling or injecting near concealed electric heating elements or hydronic tubing can damage the heating system. Even if an installer believes they know the location of the components, Stone Science does not recommend this application.

We do not recommend wall-tile injection as a standard application for this system. Our adhesive is self-leveling, so on a vertical surface it may migrate or collect at the bottom instead of remaining evenly distributed. Never inject into drywall or anywhere moisture is present; adhesive or moisture may damage the assembly.

Some flooring professionals use other adhesive-injection techniques on walls, but Stone Science has not established this system as a recommended wall-tile repair method.

Test an inconspicuous area first to check for potential staining or etching. If the surface is sensitive, apply several strips of blue painter’s tape around the injection site to help keep overflow off the exposed stone. Follow the product instructions and remove any residue promptly using an appropriate method for the stone.

Do not proceed until you have confirmed that the particular stone and installation are suitable for the product.

Do not use the injection system where moisture is present. Identify and correct the source of water, and have the floor assembly evaluated before attempting a repair. Injection should not be used to conceal an active leak or a moisture-damaged substrate.

Our step-by-step guide calls for returning after approximately 24 hours to patch the injection openings with a color-matched grout, caulk, or epoxy suitable for the surface. Actual curing time depends on the adhesive, temperature, site conditions, and patching product. Follow the product’s specified cure times before patching or returning the floor to service.

Flush the system promptly after use rather than leaving adhesive in the hose or injection tool overnight. Follow the sprayer manufacturer’s flushing procedure: recover remaining adhesive into the adhesive bucket, switch to the appropriate clean-water setup, and continue flushing into a waste bucket until the discharge runs clear.

Follow the manufacturer’s pressure-relief and shutdown procedures before disconnecting hoses, fittings, or the needle. Refer to our How to Use guide for the complete sequence.