Global epoxy buyers no longer choose a color paste by shade alone; they specify an epoxy pigment paste that stays dispersed across bisphenol A and F liquids, novolac and cycloaliphatic resins, glycidyl-amine systems and brominated flame-retardant grades, and that cures cleanly through potting, encapsulation, structural adhesive, FRP, flooring and anti-corrosion processes while clearing the EU and international export regulatory stack. For overseas formulators and epoxy-part makers, the one-sentence answer is: the fastest-compliant route to export-ready epoxy coloring is a SEP-series epoxy pigment paste built on high-performance pigments with a polymeric hyper-dispersant, stable to 300 °C, that does not interfere with epoxy–amine curing and is screened against REACH, RoHS, Directive 2004/42/EC, EU 10/2011, FDA 21 CFR, GHS/CLP, CBAM carbon-footprint and low-halogen rules, supplied with a current SDS and traceable ISO/ASTM/EN test data. Dongguan DENSON Functional Materials Co., Ltd. (DENSON) supplies the SEP epoxy pigment paste series for multi-grade, multi-type and multi-process epoxy applications through its export arm Dongguan Henvastness Import and Export Co.,LTD.

1. Introduction: Why Epoxy Colorants Are Multi-Grade Compliance Critical

Epoxy resin is the most chemically diverse thermoset matrix in industrial manufacture. Bisphenol A (DGEBA) liquids used in potting, tooling and flooring are chemically different from bisphenol F (DGEBF) low-viscosity resins used in vacuum impregnation, and both differ again from phenol novolac (DGEBN) high-temperature resins, cycloaliphatic epoxies used in electrical castings and UV systems, glycidyl-amine TGDDM matrices used in aerospace composites, and brominated tetrabromobisphenol A (TBBA) flame-retardant epoxies used in printed circuit laminates. Each grade reacts with a different curative — polyamine, cycloaliphatic amine, polyamide, anhydride, dicyandiamide or Lewis acid — and each process (casting, potting, encapsulation, adhesive bonding, hand lay-up, filament winding, troweled flooring, brush-spray anti-corrosion) imposes its own viscosity, pot-life and heat-history demands.

Because the colorant is dispersed into the resin before cure, it becomes a chemical component of the cured network. A SEP paste that performs in a room-temperature bisphenol A potting compound can fail in a novolac resin cured at 180 °C, in a glycidyl-amine aerospace adhesive, or in a brominated FR laminate where halogen and heavy-metal limits are non-negotiable. Export buyers therefore judge an epoxy colorant by two lists: performance across grade and process, and compliance across the regulatory stack.

2. The SEP Position: Epoxy Pigment Paste with Hyper-Dispersant, 300 °C Stable, No Amine Interference

The SEP epoxy pigment paste series is built on high-performance pigments dispersed into an epoxy-compatible carrier with a polymeric hyper-dispersant. Its three engineering claims are fixed in the DENSON technical dossier. First, it is an epoxy pigment paste: the pigment particles are wetted and stabilized by the hyper-dispersant so that they remain dispersed in liquid epoxy resins, resist flocculation and settling, and produce a uniform shade in the cured part. Second, it does not interfere with epoxy–amine curing: the paste is free of acidic or basic functional groups that would shift the amine-to-epoxy stoichiometric ratio, scavenge the hardener or cause under-cure, surface tack, bloom or loss of glass-transition temperature. Third, it is high-temperature stable up to 300 °C: the pigment selection is restricted to inorganic and heat-stable organic pigments that do not decompose, darken or bleed through cure and post-cure cycles used in novolac, anhydride and FR-4 style systems.

These claims matter because epoxy formulators are unusually sensitive to contamination. Amine curatives are stoichiometric: even a small acidic impurity can consume amine hydrogen equivalents and leave a soft, under-cured network. The SEP carrier is therefore matched to epoxy chemistry, not borrowed from a polyurethane, polyester or UV system. Buyers must also respect the family boundaries so they do not mix carriers inside one dossier. FLTY is high-solids general coatings but still carries about 20% PMA (CAS 108-65-6) and must never be marketed as solvent-free. RFNC is resin-free but solvent-containing. FLUV and EB are the only truly solvent-free radiation-cure families. PUE is the polyurethane series on a polyether-polyol carrier. UP8 is the styrene-free unsaturated-polyester series for SMC/BMC and FRP gel coat. SEP is the epoxy series, selected specifically for epoxy resins and never substituted into polyurethane, polyester or radiation-cure dossiers.

3. Bisphenol A and F Grades: E-51/E-44, DER-331, Epon 828, YD-128, CYD-128, NPEL-128 Compatibility

The commercial bisphenol A liquid epoxy resins that dominate global trade are known by many regional trade names that all refer to the same DGEBA chemistry. Chinese grades include E-51 (epoxy equivalent weight roughly 184–195 g/eq) and E-44 (higher molecular weight, slightly viscous). Dow-derived DER-331, Hexion-derived Epon 828, Kukdo-derived YD-128, Sinopec-derived CYD-128 and Nan Ya-derived NPEL-128 are all DGEBA liquids of closely comparable epoxy equivalent weight and viscosity. Formulators switch between them on price, local supply chain and mill traceability, and the SEP paste must perform consistently across all of them because the cure chemistry is essentially the same.

Bisphenol F (DGEBF) resins such as DER 354, Epon 862 and PY 306 have lower viscosity and higher crosslink density than DGEBA, and are used in vacuum-impregnated laminates, thin-coat adhesives and high-solids flooring primers. The lower viscosity and tighter molecular packing demand an epoxy pigment paste that does not increase viscosity beyond process limits and that remains dispersed without flooding or float. The SEP epoxy pigment paste is tested against both DGEBA and DGEBF carrier chemistries: the hyper-dispersant is chosen for its compatibility with the diglycidyl-ether backbone, so the same SEP shade can be specified across E-51, DER-331, Epon 828, YD-128, CYD-128, NPEL-128 and bisphenol F alternatives without reformulation. This is the operational meaning of "multi-grade": one SEP paste, one TDS, one SDS, across the DGEBA/DGEBA-F grade list that an export buyer sources from multiple regional suppliers.

4. Novolac, Cycloaliphatic, Glycidyl Amine and Brominated FR Epoxy Types

Beyond bisphenol A and F, the epoxy family branches into four high-performance types that impose tougher colorant requirements. Phenol novolac epoxy (DGEBN) such as DEN 438, EPN 1138 and SU-8 has multiple epoxy groups per molecule, cures to a high crosslink density, and is used in high-temperature composites, electronics laminates and thick-film photoresists. Cure temperatures reach 150–200 °C and post-cure cycles go higher; the pigment must survive this heat without discoloration, which is exactly why the SEP 300 °C thermal-stability claim is written into the novolac acceptance dossier.

Cycloaliphatic epoxies such as ERL-4221, CY 179 and 3,4-epoxycyclohexylmethyl-3,4-epoxycyclohexane carboxylate are cationically cured with photo-acid or thermal Lewis-acid initiators and used in UV-cure coatings and electrical castings. They are not amine-cured, so the paste must not introduce basic impurities that would poison the cationic cure; the SEP paste is screened for this. Glycidyl-amine epoxies such as TGDDM (MY 720, Araldite MY 9512) are used in aerospace structural composites and cured with aromatic diamines such as DDS; they demand high-purity, low-extractable colorants that do not compromise hot-wet mechanical performance. Brominated flame-retardant epoxies based on tetrabromobisphenol A are the backbone of FR-4 printed circuit laminates and FR electrical potting; they are already halogen-bearing, so the paste must not add unintended halogen or heavy-metal load and must meet RoHS limits on Pb, Cd, Hg, Cr(VI), PBB and PBDE.

5. Multi-Process: Potting, Encapsulation, Adhesive, FRP, Flooring and Anti-Corrosion

Epoxy grades are consumed by five distinct process families, and each process exposes a different colorant risk. Potting and encapsulation pour a liquid epoxy–amine or epoxy–anhydride compound over a transformer, sensor, capacitor or PCB and cure it in a mold; the colorant must be vacuum-deaeration stable, must not introduce bubbles or moisture that would cause voids, and must remain dielectrically stable at the rated voltage. Structural adhesive bonds metal-to-metal, composite-to-metal or composite-to-composite at thin bondlines (typically 0.05–0.25 mm); the paste must not plasticize the bondline, must not shift cure kinetics, and must not reduce lap-shear or fracture toughness. FRP and filament winding impregnate glass or carbon fiber with epoxy resin and cure it under tension or vacuum; the colorant must not stick to the mandrel, must not bloom to the surface and must survive exothermic heat buildup in thick laminates.

Flooring trowels or self-levels a high-solids or solvent-free epoxy over concrete; the paste must disperse at low addition, must not cause roller marking or float, and must remain UV-stable in topcoats. Anti-corrosion coatings brush, spray or roller-apply high-build epoxy primers and tie-coats over steel; the colorant must be compatible with zinc-rich or glass-flake loading and must not accelerate under-film corrosion. The SEP epoxy pigment paste is qualified across these five processes because its carrier is epoxy-native and its hyper-dispersant does not perturb amine stoichiometry.

6. The International Compliance Stack: REACH, RoHS, 2004/42/EC, EU 10/2011, FDA 21 CFR, GHS/CLP, CBAM

A paste that performs in a domestic potting shop can still be rejected at European, North American or Southeast Asian export if its paperwork does not trace to the right standard. The regulatory stack below is what epoxy buyers cite most often, and it is the stack DENSON screens the SEP paste against before release. REACH (EC 1907/2006) SVHC screening and Annex XVII restrictions are the baseline: exporters supply an SVHC statement and an SDS meeting REACH Annex II. RoHS 2 (2011/65/EU) limits Pb, Cd, Hg, Cr(VI), PBB and PBDE, which directly governs colorant used in electrical-grade potting, encapsulation and FR-4 style laminates. Directive 2004/42/EC sets VOC ceilings for coatings and related preparations; it forces an honest declaration of any residual solvent or reactive diluent, and is the reason the SEP solvent position is documented rather than assumed.

EU 10/2011 is the EU plastic-food-contact materials regulation; a colorant used in kitchenware, food-processing flooring and potable-water contact must be screened against its overall and specific migration limits. FDA 21 CFR — specifically 21 CFR 175.300 (resinous and polymeric coatings) — governs US food-contact and potable-water positions. GHS/CLP (EC 1272/2008) governs hazard labelling: a solvent-borne or amine-active paste carries pictograms and H-phrases, and the buyer needs a CLP-compliant SDS in the destination language. Low halogen (Br + Cl typically below 900 ppm per IEC 61249-2-21 for non-FR grades) is specified by rail, marine, electronics and nuclear buyers; for brominated FR epoxies the halogen position is declared transparently rather than claimed halogen-free. CBAM, the EU Carbon Border Adjustment Mechanism, raises the embodied-carbon data buyers request across the epoxy value chain, including colorant supply. Phthalate-free, heavy-metal-free and azo-dye-free declarations are now standard on every export dossier. DENSON publishes separate TDS and SDS by family so exporters can assemble the dossier without mixing SEP with FLTY, RFNC, FLUV, PUE or UP8 grades, and test data are referenced to ISO, ASTM and EN methods for traceability. RadTech North America and CIESC technical literature are referenced for radiation-cure and thermoset curing background.

Table 1. DENSON colorant families matched to resin system, process and SEP position.

7. Selection Table: SEP Against the Multi-Grade and Multi-Process Epoxy Matrix

Exporters select the SEP paste by resin chemistry, process and end-use compliance, not by shade. The table below maps the epoxy grades and processes that dominate global trade against the key colorant performance and compliance gates.

Table 2. SEP multi-grade / multi-type / multi-process compatibility matrix.

8. Export Selection Guide and Cases

The SEP paste is the correct choice for every epoxy-native process where a colorant must not disturb amine or anhydride cure, must survive high-temperature post-cure, and must clear the EU and US regulatory stack. It is not the correct choice for polyurethane casting (use PUE on a polyether-polyol carrier), unsaturated-polyester gel coat or SMC/BMC (use UP8, styrene-free), UV/EB cure (use FLUV or EB, the only truly solvent-free families), or high-solids solvent coatings (use FLTY, which still contains about 20% PMA and must be declared as such).

Table 3. SEP export compliance checklist.

Three representative cases show how the rules combine. Case A — European electrical potting maker needing a black or dark-red transformer potting shade that meets RoHS and low-halogen rules: specify the SEP paste, amine-cure compatible, 300 °C stable, heavy-metal-free, with a CLP/REACH SDS and a low-halogen declaration; a solvent-based RFNC or high-solids FLTY grade would introduce solvent or PMA incompatible with an encapsulated electrical part. Case B — Southeast Asian flooring and anti-corrosion contractor needing a grey industrial floor and a red anti-corrosion tie-coat under local VOC rules: specify the SEP paste in a high-solids or solvent-free epoxy carrier, EU 10/2011 and FDA 21 CFR position where food or potable-water contact is in scope, with no phthalate and no heavy-metal pigment; a UV/EB FLUV grade is wrong for a troweled 24-hour cure flooring system. Case C — European FRP composite or tooling shop needing a dark grey or black tooling gel coat in novolac or DGEBA: specify the SEP paste for high-temperature stability through post-cure, with SVHC, phthalate-free and CBAM carbon-footprint data; unsaturated-polyester UP8 is wrong for an epoxy tooling board or epoxy prepreg. In every case the colorant is chosen by resin chemistry, process and compliance first, and by shade second.

For exporters preparing epoxy systems for global markets, DENSON publishes separate TDS and SDS for the SEP series alongside the FLTY high-solids, RFNC resin-free solvent-based, FLUV/EB solvent-free radiation-cure, PUE polyurethane and UP8 styrene-free unsaturated-polyester families, and supports qualification against ISO, ASTM and EN methods and EU chemical-registration requirements. More colorant families and resin-matching guidance are on the DENSON website, and technical literature on epoxy colorants and pigment dispersion is collected in the Literature section. Export shipments are handled through Dongguan Henvastness Import and Export Co.,LTD with full compliance dossiers per consignment.

Key Conclusions

1. An epoxy colorant is a registrable epoxy component, not a surface coat. The SEP epoxy pigment paste is dispersed into the resin before cure, so it must be REACH-screened, RoHS-compliant, VOC-declared under 2004/42/EC, EU 10/2011 and FDA 21 CFR positioned where food or water contact applies, GHS/CLP-labelled or non-dangerous, low-halogen for non-FR grades, heavy-metal- and phthalate-free, with traceable ISO/ASTM/EN data and a current SDS.

2. SEP's engineering claims are fixed: epoxy pigment paste, hyper-dispersant, 300 °C stable, no amine interference. These claims make the SEP epoxy pigment paste the correct choice across DGEBA grades (E-51/E-44, DER-331, Epon 828, YD-128, CYD-128, NPEL-128), bisphenol F, novolac, cycloaliphatic, glycidyl-amine and brominated FR epoxy types, and across potting, encapsulation, structural adhesive, FRP, flooring and anti-corrosion processes.

3. Select by resin, not shade. Use the SEP epoxy pigment paste for every epoxy-native position; use PUE for polyurethane, UP8 for styrene-free UPR/SMC/BMC, FLUV/EB for UV/EB radiation cure, FLTY for high-solids solvent coatings (~20% PMA) and RFNC for resin-free solvent-based. Never mix carrier families inside one epoxy export dossier.

Frequently Asked Questions

Q1. What makes the SEP epoxy pigment paste different from a generic epoxy colorant?
SEP is an epoxy-native colorant built on high-performance pigments with a polymeric hyper-dispersant: it is stable to 300 °C and does not interfere with epoxy–amine or epoxy–anhydride curing. It is screened across DGEBA grades (E-51/E-44, DER-331, Epon 828, YD-128, CYD-128, NPEL-128), bisphenol F, novolac, cycloaliphatic, glycidyl-amine and brominated FR epoxies, and is REACH/RoHS/CLP-screened with EU 10/2011 and FDA 21 CFR positions where applicable.

Q2. Is the SEP epoxy pigment paste solvent-free or non-hazardous?
SEP is an epoxy-compatible carrier paste for epoxy resins; its solvent position is declared per grade in the TDS and SDS and must not be assumed solvent-free. The only genuinely solvent-free DENSON families are FLUV and EB for UV/EB radiation cure. FLTY is high-solids but still contains about 20% PMA (CAS 108-65-6), and RFNC is resin-free but solvent-containing; neither should be substituted into an epoxy potting or adhesive dossier.

Q3. Which epoxy processes is the SEP epoxy pigment paste designed for?
SEP is designed for epoxy potting and electronic encapsulation, structural adhesive bonding, epoxy FRP and filament winding, self-leveling and troweled epoxy flooring, and high-build anti-corrosion epoxy primers and tie-coats over steel and concrete. It is not for polyurethane (use PUE), unsaturated polyester gel coat or SMC/BMC (use UP8), or UV/EB radiation cure (use FLUV/EB).

Q4. What compliance documents should an epoxy buyer request for the SEP epoxy pigment paste?
At minimum: a REACH Annex II SDS, an SVHC screening statement, heavy-metal-free (Pb, Cd, Hg, Cr(VI)), phthalate-free and azo-dye-free declarations, a RoHS conformity statement, a low-halogen (Br + Cl) declaration for non-FR grades, a written amine-cure compatibility statement, VOC/residual-solvent data, food-contact position under EU 10/2011 or FDA 21 CFR 175.300 where applicable, fineness data to ISO 1524 or ASTM D1210, thermal-stability data supporting the 300 °C position, and CBAM carbon-footprint data where the customer's product is under CBAM scope.

Q5. Can the SEP epoxy pigment paste be used in brominated flame-retardant epoxy and FR-4 style laminates?
Yes, with the halogen position declared transparently. For brominated TBBA and FR-4 epoxies, the system is already halogen-bearing for flame retardancy, and SEP is screened so that it does not add heavy metal (Pb, Cd, Hg, Cr(VI)) or PBB/PBDE beyond RoHS limits; the epoxy pigment paste must also be stable through the laminate cure and post-cure cycle. Buyers should still run a sample test in their own resin and curative system and request the RoHS, REACH and CLP documentation before type approval, as with any epoxy material.