FAQ – Flexlock Sands

Can the dust/sand be used on a vertical surface?

It is not intended to be used on walls but for small areas you can Mix the Flexlock Dust / Sand with water to about the consistency of cookie dough. Mist the vertical joint with water and trowel the mixed dust/sand into the joint. When doing this you have about 20 minutes open time before the material becomes unmanageable

Will de-icing salt hurt Polymeric Sand or Dust?

If the Sand or Dust is properly cured the de-icing salt will not hurt it.

Can the sand/dust be used around a salt-water pool?


How should I proceed if I find I have under watered the sand or dust?

This will depend how long ago that it was first activated. Let your sprinkler run on it for about 1 hour. If there is a crust on the top of the sand or dust make small holes in the joints in order to allow the water to seep in. If it doesn’t harden after a few days of good weather you will have to remove the sand/dust and redo it.

Is Flexlock Polymeric sand synthetic or organic?

Our product contains oil-based polymers (synthetic) that are more durable and have better erosion resistance than organics. Our polymeric sands and Flexlock Dust do not contain any cement.

How long should you wait before walking or driving on the pavers?

As long as it is dry, it can be driven or walked on in 24 hours.

How long will the sand/dust last before it needs to be replaced?

For Flexlock polymeric sand and Dust – If the proper installation procedure is followed in terms of paver installation according to the ICPI and the Polymeric Sand installation according to Flexlock, then 10 years. The area needs to be maintained and cleaned from time to time dirt should not be allowed to accumulate on the joints.

If there is a heavy rain shortly after applying Flexlock Dust, how will it affect the application?

You will need to be patient and give it time to dry out in order to evaluate, if it has not washed out of the joint and is hardening everything will probably be all right
Note: in our instructions we recommend 24 hours no rain.

What is the minimum thickness of a paver / stone for the sand / dust to be effective?

It needs to be installed the full depth of the paver or stone.

What can be used to clean moss, mold & mildew from the joints?

Normally a pressure washer – if the moss or mildew has been there for a long time it may have damaged the sand– Remove the damaged sand where it can be readily removed using the pressure washer, allow the area to dry and replace missing sand and activate as per our directions. Note: Use the Flexlock M3 product as part of your home maintenance program. It will help prevent the growth of Moss, Mold & Mildew from returning.

Why does the sand / dust need to be 1/8” below the top of the paver / stone?

The material should not be walked on, or driven on – it needs to be protected by the stone or paver so that it does not become damaged.

Is there a product that can be used to color the sand / dust?

No. We have not done any testing on adding any colorant. We do not recommend doing this because the color additive might not be compatible with our Polymeric Sand. The colorant may also stain your pavers or stone. The color of our sand and dust are the natural color of the aggregate in the product.

Can sand be applied on top of Flexlock Dust in order to get the look of sand in wider joints?

Yes but it needs to be carefully activated with water – because with a thin layer of sand the glue Can be easily washed away – experimentation on watering is necessary test first. Do a small test Area to determine if the results are to your satisfaction.

Why do some areas harden and others stay soft?

Hard means that the area is dry – soft means that the area is still damp or wet. The reason is that some areas that are staying wet because they are not draining as fast, as the dry areas.

Note: Polymeric sand is not a mortar and it is designed to transition from hard and dry to soft when wet, this is how it is able to be self-healing.

Can the joint be partially filled with regular sand?

No this is very bad to do; it will cause the joint surface to peel and to flake off and voids any warranty.

Which sand is the strongest / hardest?

Strongest and hardest are not necessarily the most important requirements of polymeric sand. Polymeric sand is not measured by strength there is no official test for the strength test for polymeric sand. If a polymeric sand is too hard, it can also be too brittle causing cracking from ground movement. Our Flexlock Ultra sands are our most resilient. Note: Polymeric sand is intended to be a cohesive joint material and do three things: help prevent weeds, insects and erosion.

What is different about the Flexlock Ultra that allows it to work without a drainage bed?

Flexlock Ultra is formulated to repel water, and not to absorb much water. This makes it the ideal product for overlays.

What causes the white residue on pavers and what can be used to remove it?

White residue can be efflorescence, caused from wetting the pavers to activate the sand – it can also be from the polymer residue that was not properly cleaned off. Note: If the Polymeric Sand is installed on wet pavers, you will have a white residue on the paver surface. This is because the polymers are reacting and dissolving and sticking to the wet paver surface.
Note: Whether you are dealing with efflorescence from the pavers or residual polymers on the surface, A good cleaning with Flexlock Efflorescence cleaner should remove either from the surface. If the Efflorescence is especially bad, repeat applications may be necessary. If there are physical sand Particles left on the surface, they will require a pressure washer to remove before the efflorescence Cleaning. None of Flexlock polymeric sands contain any cement therefore will not cause any Permanent stain.

Can the polymeric sand be used with clay pavers?

Caution must be taken when applying the sand to clay paver joints. Clay pavers are more porous and can still be damp when they appear dry. Note: be aware that cleaning the entire project with Flexlock Efflorescence cleaner after the sand has set may be necessary.

What will happen if the Flexlock Dust is applied at a lower than indicated temperature?

Flexlock Dust – is engineered to be installed at temperatures above 59 F. If installed at lower temperatures it may never set up and be weak and not function as it is intend to.

What will happen if the Flexlock Polymeric sand is applied at a lower than indicated temperature?

Flexlock Polymeric sand is engineered to be installed – at above 32 F. if installed at lower temperatures, it may never set up and be weak and not function as it is intend to.

Why is only the top layer of the polymeric sand / Gator dust hardening and it is dry underneath?

This is a normal condition, the crust acts like a protective layer that is on top of the densely packed polymeric sand or Gator Dust, this flexible crust is spanning from one paver chamfer to another. This crust allows for some movement, much like a hinge. Making these products ideal in freeze thaw conditions.

Why is the sand / dust not hardening?

Usually it means that there is still water in the product – if the sand does not dry, it will not harden properly.

How long does it take for polymeric haze to go away?

1. We first ask them how they installed the polymeric sand.

– Were the pavers damp during the polymeric sand install ?
– Was there cement dust on the pavers coming from cutting the pavers, or wall pieces directly on the paved surface in question ?
– We ask them if they properly rinsed off all the polymeric sand residue off the paver surface ?
– We ask them if they used a blower at the end of the installation to remove all standing water left in the paver crevices.
– This standing water contains polymers and might leave a haze at the bottom of the crevices when dry if not removed.

2. If they “Say“ they followed all our back of bag installation steps and still got a haze, chances are that it is very minor.

3. Our response is wait for 3 to 5 good rainfalls, this will make at least 80% of the haze dissipate. The remaining 20% will go away with subsequent rain fall.

4. The Alliance polymeric sands do not contain cement. Hence the rainfall being slightly acidic will clean off our polymer residue haze. Some competitors put cement in their mix,this type of haze is very hard to remove. An acid wash using the Efflorescence Cleaner is recommended.

Why is my polymeric sand joint growing mold and mildew?

Any joint that grows mold and mildew does so because of an underlying moisture problem – simply stated, the area remains wet and any area that remains wet will grow mold and mildew. There is nothing in the product that can cause mold or mildew growth. A diluted pool algaecide is an excellent solution to the problem – simply spray it on several times a year to prevent growth.

How long do I need to wait before rainfall?

Our product is considered “rainproof” in one hour at temperatures over 32° F degrees. That being said, the product obviously will cure faster on a sunny 95° F degree day with 0% humidity than on an overcast 35° F day with 80% humidity. There is also a difference between a drizzle or even a steady rain and a tropical downpour of 4 inches per hour. Try to use some common sense when installing the product, if the weather is suspect try to wait for more ideal conditions.

Can I use regular sand to fill up half the joint and place Flexlock Polymeric Sand or Stone Dust on top?

We do not recommend doing this – we recommend that the entire joint depth be filled with our sand or stone dust product in order to ensure that you have a successful installation. Without a firm densely packed base, water and ice can work their way into the joint and cause the material on top to fail. It is also next to impossible to evenly fill up half a joint with one material – you will have some areas halfway and some areas where they are 7/8 of the way full. We refer to this as topping, this can cause the sand to fail and come out of the joint. Furthermore doing this is also a false economy as the work in attempting this procedure this will greatly outweigh any anticipated savings in material.

What can I use for a cobblestone driveway apron?

Use Eurostone Bond Polymeric Sand.

Can I install polymeric sand or Flexlock Dust on my pavers lain over concrete?

Flexlock manufactures the only product on the market approved for use over existing concrete – Flexlock Ultra. This product is less permeable to water and specifically engineered to shed water. Flexlock Ultra can be installed on non-drainage bases and on conventional drainage bases.

What is the correct installation height for polymeric sand?

Polymeric sand and stone dust should be installed 1/8 of an inch below the surface of the paver or stone and set below any chamfered edge. Polymeric sand will expand slightly when wet and could possibly expand above the surface of the surrounding material resulting in it being tracked out of the joint.

Why does my polymeric sand seem to be cracking?

Polymeric sand and stone dust will not crack on their own – any cracking that occurs is a result of movement – movement of the pavers or natural stone, usually a rocking motion that will cause cracking. Polymeric sand and stone dust, are intended to help prevent weeds, erosion, burrowing insects, and do not have shear strength, like concrete. Pavers and natural stone need to be properly supported by the base and in the case of pavers, they must actually touch each other to function as they are intended.

How do I remove a paver after installing polymeric sand?

Using a utility knife cut the polymeric sand all around the paver. Then scrape out as much material as possible. Use a paver extractor to wiggle the paver back and forth until paver can be removed. An alternative method is to break one paver into pieces, then adjoining pavers can be removed manually by hand. Or wait untill after a rainfall softens the material or run a sprinkler on the surface a couple of hours the evening before, do not allow the area to dry before attempting removal.

How do I remove set up polymeric sand from a paver surface?

The best way to remove polymeric sand from a paver surface is to use a hot water pressure washer at 180°F. The heat will reactivate the polymers in the product and allow the sand to be stripped away. If it is a smaller area use boiling water.

How do I remove white haze?

A white haze can be removed with efflorescence cleaner or a hot pressure washer. Alliance Gator products do not contain any Portland cement, so any hazing is easily removed and will weather away naturally with time and rain.

Why do I get white haze?

High humidity or damp pavers can cause a white haze, make sure pavers are completely dry before installing polymeric sand and try to work in low humidity. A propane torch is great for drying out small wet areas. If humidity is high, work small sections and do not allow the sand to remain on the surface for a long time. White haze can also be caused by improper cleaning of the paver surface prior to water application. A fine bristle broom cleaning and blowing with a leaf blower until dust does not rise from the surface is necessary before activating the product. You should blow the dust off from several different directions. If the paver or stone surface is textured, use a leaf blower on the surface after the final watering to prevent any white pockmark type stains from forming due to ponding water in clefts and crevices.

How much should I water the material to activate it?

Both the sand and the stone dust should be watered 3 times, starting with a fine mist and progressing on to heavier watering using a rinsing action until water begins to accumulate on the surface. On a hot day more water may be necessary as surface evaporation dries the water before it can penetrate the product. Please refer to our instructions and video.

I already compacted my pavers, why do I need to compact the sand after sweeping it?

Compacting the sand after installing ensures that the material is densely packed in the joints and eliminates air pockets, which results in a better-finished installation. If the material is not properly compacted it remains too “fluffy” and vulnerable to water penetration and failure. In the case of a slab or stone that cannot be compacted, tapping with a 2×4 or rubber mallet is required to ensure proper consolidation. Lack of proper compaction is a common cause of joint failure.

Where can I buy the product?

Call us at 1-866-212-1611 we will be glad to assist you.