E621 Flexible Control Joint Filler | 100% Solids | Up to 100% Elongation | Self-Leveling

COVERAGE RATE

MIXING AND APPLICATION INSTRUCTIONS

SURFACE PREPARATION

New concrete must be cured at least a minimum of 28 days before applying E621. All laitance, efflorescence, sealers, curing compounds, chemical contaminants, grease, oil and other freign material must be removed. The prepared surface must be clean, dry and structurally sound. High pressure water clean or dry abrasive blast may be necessary to clean existing joints.

MIXING INSTRUCTIONS

Best results are obtained if both Base and Hardener are stored at or above 75F for 24 hours prior to mixing to ensure normal viscosity.

E621 is prepared by mixing 1 part Base (Part A) to 1 part Hardener (Part B) by volume with a slow speed explosion proof drill with a Jiffy mixer for approximately 2-3 minutes.

APPLICATION PROCEDURE

The minimum depth of the joint should be 1″. The maximum width should be 3/4″. Backer rod is not recommended. E621 is a full depth joint filler.

For joints wider than 3/4″ make an Epoxy mortar out of the E1000 Epoxy Concrete Repair Kit. Apply and pack into entire joint. Allow to cure for 24 hours then saw cut down the middle to create the new joint.

E621 may be applied by pouring, tooling or with a caulking gun. Two passes may be required as pourable materials have a tendencey to dish out. The filled joint must be flush with the floor. E621 is designed for saw cut/ control joints. Do not use on expansion joints.

SHELF LIFE

The shelf life of CF-621 is in excess of 12 months when stored at 50°- 90°F or below.

CAUTIONS

CF-621 Flexible Epoxy is not a fire hazard; the flash point is above 200°F.  However, under conditions of fire it will burn and release potentially toxic fumes.  The Base portion is relatively inert physiologically.  The Hardener portion contains amines and related materials.  These can cause irritations and possibly chemical burns to the skin and eyes.  This is also true for mixtures of Base and Hardener.  Wear safety glasses, gloves, and protective clothing when using CF-621 Flexible Epoxy. In case of eye contact, flush with water for at least 15 minutes.  For skin contact, wash with soap and warm water.  Clean contaminated clothing before reuse.  This product is sold without warranty as to performance expressed or implied.  Users are urged to make their own tests to determine the suitability for their particular conditions.

SEE SAFETY DATA SHEET FOR FULL SAFETY PRECAUTIONS. KEEP AWAY FROM CHILDREN. NOT FOR RESIDENTIAL USE. FOR PROFESSIONAL AND INDUSTRIAL USE ONLY.

SEE MATERIAL SAFETY DATA SHEET FOR FULL SAFETY PRECAUTIONS.  FOR PROFESSIONAL AND INDUSTRIAL USE ONLY  KEEP AWAY FROM CHILDREN.  NOT FOR RESIDENTIAL USE NOTICE TO BUYER: DISCLAIMER OF WARRANTIES AND LIMITATIONS ON OUR LIABILITY We warrant that our products are manufactured to strict quality assurance specifications and that the information supplied by us is accurate to the best of our knowledge. Such information supplied about our products is not a representation or a warranty. It is supplied on the condition that you shall make your own tests to determine the suitability of our product for your particular purpose. Any use or application other than recommended herein is the sole responsibility of the user. Listed physical properties are typical and should not be construed as specifications. NO WARRANTY IS MADE, EXPRESSED OR IMPLIED, REGARDING SUCH OTHER INFORMATION, THE DATA ON WHICH IT IS BASED, OR THE RESULTS YOU WILL OBTAIN FROM ITS USE. N0 WARRANTY IS MADE, EXPRESSED OR IMPLIED, THAT OUR PRODUCT SHALL BE MERCHANTABLE OR THAT OUR PRODUCT SHALL BE FIT FOR ANY PARTICULAR PURPOSE. NO WARRANTY IS MADE THAT THE USE OF SUCH INFORMATION OR OUR PRODUCT WILL NOT INFRINGE UPON ANY PATENT. We shall have no liability for incidental or consequential damages, direct or indirect. Our liability is limited to the net selling price of our product or the replacement of our product, at our option. Acceptance of delivery of our product means that you have accepted the terms of this warranty whether or not purchase orders or other documents state terms that vary from this warranty. No representative is authorized to make any representation or warranty or assume any other liability on our behalf with any sale of our products. Our products contain chemicals that may CAUSE SERIOUS PHYSICAL INJURY. BEFORE USING, READ THE SAFETY DATA SHEET AND FOLLOW THE PRECAUTIONS TO PREVENT BODILY HARM.

What is E621 Flexible Control Joint Filler?

E621 is a two‑component, 100% solids flexible epoxy joint filler designed to fill and protect saw cut or control joints in on‑grade concrete slabs. It offers excellent bond strength and resilience under heavy load traffic conditions.

Where should E621 be used?

Use E621 in industrial, commercial, and manufacturing environments such as:
✔ Chemical processing plants
✔ Warehouses
✔ Pulp & paper mills
✔ Sewage treatment facilities
✔ Petroleum refineries
✔ Electric generating stations
✔ Marine installations
✔ Concrete slabs on grade
It is not recommended for expansion joints or outdoor environments. For a full product selection on joint fillers check out our Joint Filler Page. To help with selecting the right product for YOUR project reach out to us at 630-675-4509 or [email protected].

Can E621 handle heavy traffic?

Yes — E621 offers good resistance to steel wheel traffic and provides a resilient bond that helps prevent edge erosion of control joints even under frequent load.

What does “100% solids” and “up to 100% elongation” mean?

100% solids means there are no solvents that evaporate during curing — resulting in a strong, dense material with minimal shrinkage.
Up to 100% elongation means the cured filler can stretch with joint movement without cracking, making it ideal for dynamic concrete slabs.

Is E621 self‑leveling?

Yes — the product is designed to self‑level, allowing for easy application and a smooth, flush finish in control joints without extensive tooling.

How do I apply E621?

1. Ensure new concrete is cured ≥28 days and the surface is clean and structurally sound.
2. Mix Part A (base) and Part B (hardener) at 1:1 by volume with a slow‑speed drill and mixer.
3. Apply by pouring, tooling, or using a caulking gun.
4. Ensure joint depth is at least 1″ and width up to 3/4″. Two passes may be necessary for full fill.

Can I use backer rod with E621?

No — backer rod is not recommended. E621 is intended for full‑depth filling of control joints.

What size joints can E621 fill?

✔ Minimum depth: 1″
✔ Maximum width: 3/4″
For joints wider than 3/4″, a mortar repair and re‑sawcut method is recommended before applying this filler. For additional help selecting the right product for your project reach out to us at 630-675-4509 or [email protected].

Is E621 VOC‑free?

Yes — E621 has 0 g/L VOCs, meaning it has no volatile organic compound emissions and is USDA approved for allowable incidental contact surfaces.

Is E621 suitable for residential use?

No — this product is intended for professional and industrial environments only and is not recommended for residential applications.

How should I prepare the surface before application?

Remove all laitance, sealers, curing compounds, oils, dirt, and contaminants. The surface must be clean, dry, and structurally sound. Blast cleaning or high‑pressure washing may be necessary.

Are there any safety precautions?

Wear appropriate PPE — gloves, eye protection, and protective clothing — when handling the product. In case of contact, flush skin or eyes with water and follow your company’s safety protocols. Consult the Safety Data Sheet for detailed guidelines.

Can E621 be used outdoors?

No — E621 is not recommended for exterior applications or as an expansion joint filler. It is optimized for indoor, on‑grade control joints where flexibility and heavy traffic resistance are critical.