Developed for MultiJet Printing platforms, 3D Systems VisiJet M2R-BK* is a UV-curable acrylate photopolymer that produces rigid, opaque black components with a smooth jetted surface. The liquid cartridge material is designed for piezoelectric printhead deposition in the ProJet MJP 2500 series, where co-deposited wax support material is removed after the build by heat-assisted dissolution. The cured polymer is specified for functional enclosures, light-blocking baffles, clips, covers, and assembly fixtures that require a stable black appearance without secondary painting. Nominal layer thickness in MultiJet Printing is 32 µm, and the build envelope of the ProJet MJP 2500 series is 294 × 211 × 144 mm. The UV cure occurs layer by layer; no thermal post-cure is required before support removal. The asterisk designation indicates a commercial variant within the M2R rigid material family rather than a separate base chemistry. Mechanical characterization is conventionally reported under ASTM D638 and ASTM D790 tensile and flexural protocols.

How Does the Black Pigment Alter Mechanical Response Relative to M2R-TN?

Pigment selection in jetted acrylate resins changes the final crosslinked network because dispersed particles reduce the depth of UV penetration, alter the oxygen-inhibited surface cure, and introduce stress concentrations at the pigment-matrix interface. In M2R-BK, the carbon black loading provides an opaque black appearance while retaining the base M2R material-family tensile and flexural response near the natural-tone M2R-TN grade. Published datasheet values for M2R-BK indicate tensile strength at break under ASTM D638-14 in the range 45–50 MPa, tensile modulus near 2.1–2.4 GPa, and elongation at break in the 6–10% band. Flexural strength under ASTM D790-17 is typically reported between 60 MPa and 70 MPa, while notched Izod impact resistance under ASTM D256-10 remains near 20–25 J/m. These values are typical manufacturer data, not specification limits, and must be confirmed against the certificate of analysis for a specific lot. The black grade differs from clear M2R-CL primarily in optical transmission: M2R-CL transmits visible light and is used for light pipes or fluidic visualization, whereas M2R-BK blocks visible light and is selected when internal stray light must be suppressed. Because carbon black is a UV absorber, the cure depth may be slightly reduced relative to the natural or clear grades; printer parameters are therefore adjusted through the build preparation software to deliver the same nominal 32 µm layer thickness without delamination.

Processing Limits and Support Removal Sequence for MJP 2500 Platforms

Material cartridges are stored at 18–28°C because low-temperature resins increase in viscosity and high-temperature storage can shorten shelf life through premature dark polymerization. Cartridges moved from a cold storage area into a humid production room should be conditioned to ambient temperature before installation; condensation at the cartridge interface must be removed to prevent water contamination of the photopolymer. The ProJet MJP 2500 series automatically heats cartridges and maintains jetting temperature through the build, but production-scale experience shows that cartridge age and lot-to-lot viscosity variation can produce jetting streaks or drop-out if the system is not recalibrated after material changes. Black M2R-BK material is less transparent to UV than clear M2R-CL, so build preparation parameters usually include adjusted lamp energy per layer; operators should not copy clear-grade print profiles into black-grade builds without verifying initial test bars under ASTM D638-14.

During support-removal processing, the dominant failure mode for black MJP parts is thermal creep in thin unsupported features because the cured material exhibits a heat deflection temperature under ASTM D648-18 at 0.455 MPa of approximately 54°C. Production-scale handling on ProJet MJP 2500 series systems typically uses a temperature-controlled forced-air oven followed by an ultrasonic bath operating near 40 kHz to accelerate wax release from blind cavities. For black parts, wax residues are more difficult to detect visually than on clear or white grades; dimensional audits under ISO 1101 and mass verification before and after the support-removal cycle are therefore recommended when witness features or critical mounting surfaces are present. Oven set points are commonly held near 40–60°C for 20–60 min in production-scale MJP service, but published data for this specific configuration is limited; the exact values must be established on sacrificial geometry. Unsupported thin sections should not be exposed to the upper end of this range for extended periods. After wax dissolution, parts are rinsed with warm water and dried at ambient temperature to avoid water spotting. The black pigment does not alter the wax-support chemistry, but it reduces visual contrast between white residual wax and the black polymer surface, which increases the inspection burden on production lines.

Build orientation interacts with the black grade because the opaque resin can mask residual support material inside internal channels. For sighting pins, snap-fit arms, and thin-walled enclosures, the longest tensile-loaded feature is usually oriented oblique to the jetting plane to reduce layer-boundary stress concentrations. Linear dimensions are best evaluated on tensile bars under ISO 527-2 and flexural specimens under ISO 178 before production parts are measured. In practice, dimensional repeatability across a 294 × 211 × 144 mm build envelope is influenced by local irradiance uniformity, part spacing, and support removal temperature; published data for this specific configuration is limited, so first-article inspection under ISO 1101 is advisable for critical feature sizes below 1.0 mm.

When M2R-BK Replaces M2R-CL in Housing and Baffle Applications

Opaque black components are frequently substituted for clear M2R-CL or white M2R-WT parts when the assembled device requires internal absorption of visible stray light. Unlike M2R-CL, which transmits light through polished surfaces and is sensitive to surface scratching that can scatter light, M2R-BK provides a uniform black appearance through the bulk of the cross-section, reducing the need for black tape, paint, or deposited coatings. Compared with M2R-WT, the black grade offers lower surface reflectance and better visual concealment of internal components but may show a larger surface-temperature rise under radiant loads. Published data comparing the black and white grades under identical ASTM D648 thermal tests is limited; the selection decision is therefore driven primarily by optical and cosmetic requirements rather than by statistically separable mechanical differences. Parts requiring subsequent adhesive bonding should be evaluated for bond strength under ASTM D1002 or ASTM D6862 because the pigment can alter surface energy after support removal.

Surface preparation before bonding or coating is different for black M2R-BK because the pigment-rich surface can retain residual wax or oil-based cleaning medium in micro-roughness produced by the jetting process. Production facilities typically use an alcohol-based rinse followed by dry forced air at 40–50°C to prepare surfaces for cyanoacrylate or ultraviolet-curing adhesive systems. Bond strength is evaluated by ASTM D1002 single-lap shear or ASTM D6862 peel tests; values are strongly influenced by wash line temperature, rinse agent composition, and the time between drying and adhesive application. Because the material is thermoset, solvent welding used on injection-molded ABS is not applicable; mechanical fasteners, adhesives, or joining features must be designed into the printed part.

Compared with unfilled injection-molding ABS, M2R-BK provides design freedom for internal channels and consolidated assemblies but exhibits lower heat deflection temperature and lower elongation at break. Typical ABS grades can exceed 90°C under 0.455 MPa, while M2R-BK remains near 54°C; applications requiring continuous service above this threshold should use high-temperature materials or metal inserts. The notched Izod impact of M2R-BK is also lower than that of many injection-molding ABS formulations, so snap-fit features should be evaluated with mechanical tests under ASTM D256-10. In return, the jetted process eliminates tooling and supports feature sizes that would be impractical in conventional molding.

In continuous immersion service, cured M2R-BK should not be selected for ketone, chlorinated solvent, or strong alkaline media because these fluids may swell or stress-crack the crosslinked acrylate network. The material is not recommended for load-bearing applications in which continuous service temperature exceeds the heat deflection temperature under load. Finished parts should not be autoclaved or subjected to steam sterilization cycles because the combination of moisture and heat can degrade dimensional accuracy and induce warp. Published data for this specific configuration in hydrolytic or UV-weathering environments is limited; aerospace or medical use therefore requires application-specific qualification under ISO 527-2, ISO 178, or equivalent after exposure. The liquid photopolymer must be handled in accordance with the safety data sheet; uncured resin is not suitable for food-contact or implant applications. Regulatory compliance statements under REACH and RoHS are lot and configuration dependent and should be requested from the material manufacturer for the specific cartridge lot.