Cardolite: NX-8501 – New Waterborne Curing Agent For Epoxy Systems


Cardolite’s new NX-8501 is a waterborne curing agent for epoxy coatings and adhesives. This completely solvent-free curing agent enables zero and low VOC formulations without compromising performance. NX-8501 is a solution-type curing agent supplied at 80% solids in water. This material is easy to handle due to its low viscosity and ability to be further diluted by water or other co-solvents. NX-8501 is also compatible with various epoxy dispersion resins giving formulators latitude to work.

NX-8501 provides fast cure properties and hardness development regardless of the epoxy resin selected. Despite the fast dry speed, NX-8501 delivers long pot life with 3 to 4 hours of working time achieved in their studies. Amongst all Cardolite’s waterborne epoxy curing agents, NX-8501 shows the best weatherability properties with low yellowing upon exposure to UV light.

Corrosion Protection to Various Substrates

Coatings based on NX-8501 demonstrated excellent adhesion and anti-corrosion performance to a wide range of substrates. That included challenging non-blasted surfaces commonly used in automotive and agricultural and machinery equipment.  More specifically, Cardolite’s evaluation looked at NX-8501 based primers on untreated cold rolled steel, aluminum alloy, galvanized steel, and stainless steel panels. All those systems successfully withstood long exposure of over 1500 hours in the salt spray cabinet.  NX-8501 based primers also did very well on blasted steel surfaces as encountered in marine and protective coating applications. These coatings demonstrated good surface tolerance by providing excellent corrosion protection even over rusted panels. All systems were tested at low film thickness and were suitable options as primers, midcoats, and direct-to-metal (DTM) coatings.

Moreover, NX-8501 based primers can be quickly recoated by topcoats in wet-on-wet applications. Cardolite’s evaluations show that NX-8501 based epoxies can be recoated with polyurethanes in as fast as 15 minutes after application. Cure can take place at room temperature or in a 60°C oven. The final epoxy-polyurethane system provides excellent gloss (no die-back) and long-lasting corrosion protection. This makes NX-8501 a great option for automotive refinish and other applications that require quick turnaround time.

Broad Waterborne Epoxy Offering

NX-8501 joins other high-performance waterborne epoxy curing agents in their product offerings. Depending on the application, Cardolite can offer specific solutions to your applications. Their portfolio includes grades with excellent protection to various metals and concrete as well as good weatherability. Cure profile ranges from fast cure even at 10°C/80%RH to very long pot life options with quick recoatability. Additionally, good handling properties such as excellent dilution and compatibility with several epoxy dispersions and liquid epoxy resins are also available. Floor primers and self-levelers, and anti-corrosion primers, midcoats, and DTM coatings can benefit from their offerings.

Most of Cardolite waterborne epoxy curing agents derive from renewable, cashew nutshell liquid (CNSL). CNSL derivatives present unique qualities compared to widely known polyamines. These products are very hydrophobic in nature and therefore, provide excellent water and corrosion resistance. The aromatic ring in the cardanol also ensures good thermal and chemical resistance properties. The phenolic hydroxyl delivers good adhesion and cure properties.


Hall Technologies, Inc. is a specialty chemical distributor with headquarters in St. Louis, Missouri. Our technical sales team and applications laboratory collaborate with our customers in product selection and formulation. As technical leaders in the industry, we supply answers.

For more information about Cardolite’s waterborne coatings or to request a sample, contact your Technical Sales Representative today!

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