Hollow/Loose Flooring Injection Tool
The ONLY tool engineered to deliver tile restoration compounds exactly where they’re needed — beneath hollow & loose tile.
How to Use the Hollow/Loose Flooring Injection Tool
Fix the hollow. Keep the floor. No demolition, no tear-out — just a few 1/8" holes, our self-leveling adhesive, and any airless paint sprayer.
What you'll need
- Stone Science Hollow/Loose Flooring Injection Tool (kit includes the injection needle, adjustable depth collar, male-to-male adapter and 1/8" masonry bit)
- Stone Science Hollow/Loose Flooring Injection Adhesive — 1 gallon free with every tool
- Any airless paint sprayer (buy or rent — we like the kind with a bucket holder; it's easier to move around)
- Two 5-gallon buckets: one for water, one for adhesive (a 2-gallon bucket works for small jobs)
- Teflon tape, blue painter's tape, a razor blade, paper towels, and a drill
- Extra 1/8" masonry bits for large projects
Step 1 — Find the hollow spots
Tap the floor with a broom handle and listen for the hollow sound. Mark every hollow or loose tile with blue tape so you can see your whole work area.
Step 2 — Set up the tool
- Wrap Teflon tape around both ends of the male-to-male adapter.
- Screw the paint sprayer hose (female end) onto one side of the adapter and the injection tool (female end) onto the other.
- Tighten the hoses and the tool.
- Wrap Teflon tape on the injection needle, seat it in the bottom of the tool, slide the adjustable depth collar over the needle and twist it on.
- Your tool is ready. Watch our unboxing videos on social media if you want to see it done.
Step 3 — Prime with water
Put the paint sprayer's hoses in the bucket of water and press the lever handle down to run water through the system. This checks for leaks and pushes the air out of the line.
Step 4 — Switch to adhesive
Move the sprayer's intake into a bucket of Stone Science Hollow/Loose Flooring Injection Adhesive (2 or 5 gallons, depending on the job). Point the needle into the water bucket, press and hold the lever. Water will purge first — once adhesive is flowing steadily with no water, you're ready.
Step 5 — Drill relief holes
Using the 1/8" masonry bit, drill several holes around each hollow tile — one at each corner and a couple along each side. These give the tile relief from pressure so it doesn't pop. On natural stone you can also drill straight through the center of the tile.
Step 6 — Inject
Set the needle to the depth you want, place it in a drill site and press the lever. Keep the sprayer on its lowest setting — low and slow lets the adhesive self-level through the void without forcing the tile up. Too much pressure can pop a tile off.
- A little backflow at the first hole is normal. That's the initial pressure when you engage the handle. Hold for several seconds. If it keeps backing out the whole time, that spot won't take adhesive — wipe it up and move to the next hole.
- Natural stone: test an inconspicuous area first to make sure the adhesive doesn't etch the surface. If it does, run strips of blue tape around each injection site so the excess doesn't touch bare stone.
Step 7 — Plug the holes
Twist a couple inches of blue tape into a dart or cone. Push it into the drill site, cut it flush with a razor blade, then use the drill bit or needle to push it just below the surface of the grout line or tile.
Step 8 — Patch (24 hours later)
Come back the next day and patch each site with color-matched grout, caulk or epoxy, depending on your surface.
Step 9 — Clean the system
Put the sprayer's hoses back in the water bucket. Hold the lever down with the tool over the adhesive bucket until the system starts pushing out water, then move to the water bucket and keep going until the water runs clear and the tool is free of adhesive.
Important
- Do not use where moisture is present.
- Do not use around in-floor heating.
- A loose tile that has lifted can be weighted overnight (a bucket of water on top works) so it cures pressed back into place.
- Works on ceramic, porcelain, natural stone, wood, engineered hardwood and LVP.
FAQ
What causes hollow floors and cracking grout?
There is a right way to trowel thinset, and many homeowners unknowingly hire contractors who don't follow it. The ridges of thinset are supposed to collapse and make full contact with the tile when it's pressed into place. When the thinset is mixed wrong, troweled in a "rainbow" pattern, or applied in dollops ("cookies"), the ridges never collapse and you end up with pockets — large and small — under the floor. Over time those voids turn into hollow sounds, cracking grout and loose or broken tiles. Injecting our self-leveling adhesive fills those voids without the cost and disruption of ripping out your existing floor.
What is the Stone Science injection tool used for?
Our patent-pending Hollow/Loose Flooring Injection Tool is made in the USA and built to re-bond floors from underneath. If your tile is cracking because of voids or sounds hollow when you walk on it, you drill a few small relief holes and fill the void with our tool and adhesive. The adhesive cures flexible but strong — it lasts, yet the floor and thinset can still be removed later if you ever decide to change your flooring.
What floors does it work on?
Ceramic, porcelain, natural stone, wood, engineered hardwood and LVP.
Do I need a specific paint sprayer?No — any airless paint sprayer works. We like the kind with a built-in bucket holder because it's easier to maneuver. You can buy one or rent one from Home Depot or a local rental shop.
How is this different from the adhesive tubes I've seen online?
Same idea, very different delivery. Tube products are squeezed under the tile one 10-oz caulking tube at a time, on your hands and knees. Our tool feeds straight from a 2- or 5-gallon bucket through an airless sprayer — a gentle, continuous, self-leveling flow controlled by a press-and-hold lever, so you can work standing up and treat a whole room's worth of hollow tile without reloading. It's also a fraction of the cost per gallon.
How deep can the needle reach?
3/16" to 1" with the adjustable depth collar, and up to 1 1/4" without it. If you need to go deeper, drill a deeper hole — the needle doesn't have to sit at the very bottom of the void to fill it.Can too much pressure "pop" a tile off the floor?It can, but it's much less likely if you drill plenty of relief holes (one at each corner and a couple on each side) and keep the sprayer on its lowest setting — low and slow. If a tile is loose, set a bucket of water on it overnight so it cures with weight holding it back in place.
Why is there backflow at the first hole?
A little backflow at the first injection site is normal — it's the initial pressure when you engage the handle. Keep holding for several seconds. If it backs out the entire time, that spot can't take adhesive; clean it up and move to another drill site.
Will the floor still sound hollow after the repair?
The adhesive cures with a slight flex (that's what lets the floor handle micro-movement without cracking), so a repaired area can sound a little different from a tile set in rigid thinset. That's expected — what matters is the tile is bonded and stays put.
Can I use this with in-floor heating?
We don't recommend it. Some contractors will do it if they know exactly where the heating elements or tubing run, but that's not something we can personally recommend.
Can I inject into hollow wall tile?
Never inject where moisture is present or into drywall — the adhesive will make it soggy. Keep in mind the adhesive is self-leveling, so on a wall you'd need to work in sections to keep it from pooling at the bottom. We haven't personally run into a hollow wall tile job, but adhesive has been used this way in the industry for years.
Is the adhesive safe on natural stone?
Test an inconspicuous spot first. If the adhesive etches the stone, run blue tape around each injection site so excess adhesive never touches bare stone.
How much adhesive do I need?
It depends on the size of the voids. A few hollow tiles may take a fraction of a gallon; a badly failed install across a whole home can take much more. Every tool ships with a free gallon so you can start right away, and additional gallons are $55 each.
Is the tool built to last?
Yes. It's machined from aircraft-grade 6061-T6 aluminum, CNC precision machined and assembled in the USA, hand polished, anodized and laser-etched. It's a professional-grade tool meant to last a lifetime — and priced so a contractor can make it back on the first job.
Where are your products made?
Our tool, adhesive and cleaners are all made in the USA.
Who do I talk to if I have questions?
Bryan. No chatbots, no template replies — when you email Stone Science you're talking to someone who has been in the trade since 2006.
Warranty & Returns
1-Year Manufacturer's Warranty
Every Stone Science Hollow/Loose Flooring Injection Tool is covered by a one-year warranty against manufacturer defects from the date of purchase. If your tool has a defect in materials or workmanship within that year, contact us and we'll repair or replace it.The warranty covers the tool itself. It does not cover normal wear, damage from misuse, improper cleaning (for example, adhesive left to cure inside the chamber), modification, or use outside the instructions provided. Adhesive and cleaning products are consumables and are covered by our return policy below rather than the warranty.
How It Works
Why It Works
Same Proven Adhesive. Faster Application.
It’s not a different science — it’s a smarter delivery method. Stone Science helps contractors and restoration pros apply the same proven adhesive faster, with better workflow and less manual effort.
A more efficient way to inject adhesive
Traditional methods get the job done — but they can be slow, repetitive, and inefficient on larger jobs. Stone Science streamlines the process so you can move faster while still using the same trusted adhesive principles tile and stone pros already understand.
Uses the same trusted adhesive concept restoration pros already know.
Helps speed up adhesive delivery compared to repetitive hand pumping.
A better method when you want cleaner, smoother, more productive application.
THE BOTTOM LINE
Less pumping. More progress.
Traditional vs. Stone Science
Show customers exactly what makes your process different.
- Manual pumping
- Slower on larger jobs
- More repetitive strain
- Less efficient workflow
- Faster adhesive delivery
- Streamlined workflow
- Designed for efficiency
- Cleaner, more controlled application
Meet Your New Best Friend
Save tIME
On average, a 4 day restoration now takes only 5-8 hours from start to finish.
Save Money
Save money by saving time and providing a better outcome by cracking less tiles.
Made in the USA
Machine Milled & Built in California .
Flexible bond that moves with the floor
We hold ourselves and our ingredients to the highest standards.
Hi, I’m Bryan.
Hi there and welcome to Stone Science! My name is Bryan and my flooring experience began in concrete foundation work in 2006, continuing with restoring marble and setting tile for the past 10 years. Over time, I've become extremely passionate about two things. First and foremost is the customer experience...
THE PROBLEM YOU CAN'T ALWAYS SEE
Why do tile floors fail? The problem isn't always visible.
Cracked grout and broken tiles can be warning signs, but problems with the bond can begin long before you see damage. Here's what can happen underneath an otherwise normal-looking floor.
UNDER THE SURFACE
It's all about the contact.
Thinset mortar should support the tile with adequate coverage. Straight trowel ridges are designed to collapse as the tile is embedded.
Collapsed ridges create continuous contact beneath the tile.
Simplified cross-sections for illustration only; not to scale.
5 QUICK QUESTIONS
01 What are thinset ridges supposed to do?
When mortar is combed in straight lines, moving the tile perpendicular to those ridges helps flatten them into the valleys, release air, and create good contact across the back of the tile.
02 Why are 'rainbows' and 'cookies' a problem?
Curved trowel patterns can trap air. Spot-setting with separate dollops (sometimes called “cookies”) leaves gaps instead of the mortar coverage tile needs. Unsupported areas can contribute to loose or cracked tile.
03 Can incorrectly mixed thinset cause issues?
Yes. Too much or too little water, or failing to follow the product's mixing and working-time instructions, can affect how well mortar works and bonds. The correct process depends on the specific mortar.
04 Can this happen before grout or tile cracks?
Yes. Poor mortar coverage can be hidden under a floor that still looks intact. Cracks, movement, or a hollow sound can be clues, but none proves the cause by itself.
05 Is thinset coverage the only cause of floor failure?
No. Subfloor movement, inadequate movement joints, moisture, and other installation conditions can also play a role. The underlying cause should be checked before choosing a repair.
