3D Systems VisiJet FTX Gray Plastic for SLA Systems is a gray-pigmented, acrylate-based photopolymer supplied in sealed cartridges for vat photopolymerization platforms operating in the 350–405 nm UV range. The model designation is VisiJet FTX Gray. It is intended for functional prototypes, jigs and fixtures, and short-run production parts where higher elongation at break and notched impact resistance are required relative to unfilled structural SLA resins. After platform-specific post-curing, the material develops the mechanical property envelope given in the table below. The cartridge delivery format reduces batch-to-batch variation and shields the uncured resin from ambient moisture and stray UV exposure before dispensing. Representative cured-state values are shown; users should verify against the latest supplier datasheet because post-cure parameters and platform exposure can shift results by several percent.

The cured resin is a crosslinked thermoset; it cannot be thermally reshaped, solvent-welded, or recycled by regrinding. Dimensional correction by heat forming is therefore not possible, and critical fits must be produced by machining or by adjusting the build orientation before printing. The gray pigment package is added before cartridge filling and is maintained in suspension by the cartridge design. Open-tank transfer is not recommended because pigment settling changes optical density and cure depth. Cartridges should be stored at 15–30 °C; before use, the cartridge should be allowed to equilibrate to the build chamber temperature to avoid recoating defects. Mixing is not required for cartridge-fed systems because the pigment is already dispersed during manufacture. In open-room operations where relative humidity exceeds 60%, exposure of the resin tray should be minimized; absorbed water can alter cure kinetics and reduce the tensile modulus of the cured network. Support-tip fracture during green-state cleaning is a common failure mode when contact diameters are below 0.4 mm and the part is exposed to ultrasonic agitation. Ultrasonic cleaning is not recommended for thin-walled sections below 1 mm because cavitation can propagate microcracks; low-pressure solvent immersion with soft-bristle agitation is preferred.

What post-cure boundary conditions determine final ductility?

Post-cure is not cosmetic; it completes conversion of residual acrylate groups and stabilizes the amorphous network. Green parts cleaned in 99% isopropanol or propylene glycol monomethyl ether acetate are placed in a UV chamber emitting in the 365–405 nm range. For thin-wall sections up to 2 mm, the platform-specific job file commonly specifies a 60 °C post-cure cycle of approximately 30 min; thicker sections require longer exposure because UV attenuation through the gray-pigmented resin limits dose uniformity. Inadequate post-cure leaves residual monomer that can plasticize the material, lower heat deflection temperature by up to 5 °C, and increase moisture uptake under ASTM D570-22. Post-cure chambers with poorly controlled irradiance below the platform vendor’s minimum specified value produce inconsistent conversion and should not be used for production batches without validation coupons placed at multiple locations. Chambers must have air circulation to avoid hot spots; non-vented ovens can produce local temperatures above the material’s heat deflection temperature and induce warpage. After post-cure, parts should be allowed to cool to room temperature under restraint if tight flatness is required. Unrestrained cooling can permit warpage on parts with length-to-thickness ratios above 20:1 because the thermoset network cannot be stress-relieved by annealing.

The resin is formulated for low-shear handling in cartridge-fed systems. At the recommended build chamber temperature, the recoating process should achieve a uniform layer across the platform; if the chamber temperature falls below 20 °C, recoating defects such as incomplete fill and delamination are observed in production builds. Published data for the viscosity-temperature curve of this specific configuration is limited, so users should qualify the material on their own platform before committing to tight-tolerance production. Support removal should be performed before post-cure; post-curing locks in support marks and makes them more brittle. Use side-cutting pliers with sharp cutting edges; twisting supports off by hand can chip the part surface. For large flat parts, support density should be increased and support tips reduced to 0.3–0.5 mm to balance clean removal with build stability.

When dimensional control is critical, which build factors dominate part deviation?

Linear shrinkage in the green-to-postcured state and z-axis interlayer boundaries both contribute to dimensional error. Test coupons built with the long axis parallel to the xy-plane typically show higher tensile strength than z-axis coupons because the latter contain more interlayer photopolymerization interfaces. Orientation-specific validation under ASTM D638-14 is required before substituting FTX Gray for a machined acetal or ABS component. Support-tip contact regions should be placed on non-critical surfaces; post-curing locks in support marks and increases local stress concentration. Published linear shrinkage data for this specific configuration is limited; however, unfilled photopolymers of this class commonly exhibit green-to-postcured linear shrinkage between 0.4% and 0.8% along the build axis.

Surface finish on unsupported features is governed by recoating parameters and the laser or projection resolution of the host system. Layer heights of 50 µm or 100 µm produce visible stepping on shallow angles; for sealing surfaces, secondary machining or coating is required because the as-printed surface is not inherently leak-tight under gas pressure above 0.1 MPa without post-processing. The Shore D hardness of 80 permits wet sanding and drilling, but cutting tools should be operated at low feed rates to avoid thermal softening near the 51 °C heat deflection temperature at 0.455 MPa. Tapping of holes smaller than M3 is not recommended because the material provides limited chip formation; thread-forming screws are preferred over thread-cutting taps. In production-scale assembly jigs, edge chipping after repeated part insertion is the primary wear mode. A two-part polyurethane topcoat of 50–100 µm thickness is used to reduce surface abrasion; without the topcoat, the as-printed surface shows visible wear after approximately 500 insertion cycles. Published data for this specific configuration is limited, so wear testing should follow ASTM D4060.

Chemical resistance and solvent compatibility limits.

Short-term contact with 99% isopropanol is used during cleaning and is acceptable if the solvent is fully evaporated before post-cure. Prolonged immersion in ketones, chlorinated solvents, or strong alkaline solutions causes swelling, surface whitening, or crack propagation. Exposure to ethanol, sodium chloride solution, and dilute acids has limited effect at room temperature, but no long-term compatibility statement can be made without immersion testing under ASTM D543. Water absorption after 24 h at 23 °C is typically below 1.0% under ASTM D570-22, but continuous exposure to water above 40 °C should be validated because the heat deflection temperature under 1.82 MPa is 43 °C. The resin has not been formulated for long-term outdoor UV stability; direct sunlight may cause color shift and surface chalk unless a UV-stable topcoat is applied.

Differentiation from standard SLA materials is most evident in the tensile elongation and notched impact response. Unfilled general-purpose SLA photopolymers often list tensile elongation at break in the 5–12% range under ASTM D638-14, while FTX Gray reaches approximately 20%. The notched Izod impact value of 37 J/m is higher than many hard-glass SLA grades that fall below 20 J/m under ASTM D256-10. This places FTX Gray closer to a tough, semirigid engineering material than to a brittle thermoset slab resin. The comparative ranges in the second table show the property position of FTX Gray relative to unfilled general-purpose SLA resins and unfilled injection-molded ABS.

Not a direct substitute for injection-molded ABS in elevated-temperature service.

Injection-molded ABS grades can exceed 80 °C under 1.82 MPa in glass-filled formulations, whereas FTX Gray HDT at 1.82 MPa is 43 °C. Continuous service above 40 °C therefore requires creep and deflection testing under ASTM D2990. The material is also not certified for food-contact or implant use unless end-use specific validations are performed under relevant FDA or EU regulations. The 20% elongation at break permits short-term flexural strain in thin snap-fit features to approach 10% during assembly without visible fracture; however, repeated cycling should be limited to below 5% surface strain because viscoelastic recovery is not equivalent to a thermoplastic. Impact energy exceeding the notched Izod value may propagate cracks from sharp corners. Compared with castable SLA resins, the pigment loading and crosslink density are not optimized for investment casting burn-out; ash residue may exceed the limits normally specified for low-residue casting resins under ASTM D2584. Users should consult the supplier safety data sheet for hazard classification under CLP Regulation (EC) No 1272/2008 and for waste disposal under Directive 2008/98/EC.