3D Systems FabPro™ Proto GRY Plastic is a rigid 405 nm photopolymer resin supplied in cartridge form for the FabPro 1000 DLP system, which has a build envelope of 125 mm × 70 mm × 120 mm. The material is intended for general-purpose prototyping of gray components requiring form-fit verification, dimensional inspection, visual concept approval, and limited functional master patterns. It is an unfilled acrylate formulation that cures by radical photopolymerization under 405 nm LED imaging. It is not a filled composite, not an elastomer, and not a high-impact engineering resin. Manufacturer technical literature positions the material for short-run prototype geometries in which stiffness, surface definition, and printability are more important than toughness. Because datasheet revisions can alter numerical limits, the values in this document are manufacturer-referenced representative values and should be revalidated against the current safety data sheet and technical data sheet before release of a production process.

The material is distributed in sealed cartridges that reduce operator skin contact and free-liquid exposure. Cartridge storage is specified between 10 °C and 30 °C, with an installed operating temperature of approximately 20 °C to 25 °C. If a cartridge is removed from cold storage, the liquid should be conditioned for at least 12 h before printing. At ambient humidity above 60% RH, the uncured liquid can absorb water vapour. Pre-drying of the work area and immediate resealing of the cartridge are therefore required. The DLP recoat cycle is sensitive to viscosity shifts, and moisture-contaminated resin typically presents as thin-layer delamination on overhangs or as microvoids on large flat surfaces.

What mechanical property values are reported under ASTM D638, ASTM D790, and ASTM D256?

Fully post-cured specimens of FabPro Proto GRY typically show a brittle-to-rigid response. The manufacturer-reported property window is reproduced below with the controlling test standards. These figures assume post-cure in a compatible 405 nm flood curing unit, such as the 3D Systems LC-3DPrint Box or an equivalent controlled-output chamber, and test specimen conditioning according to the standard methods.

The values in the table are not independent of build orientation and part thickness. Tensile bars printed in the vertical Z direction often show lower elongation at break than XY-printed specimens because interlayer conversion is not identical to in-plane conversion. Published data for this specific orientation-dependent anisotropy in Proto GRY is limited. Comparative tests on similar unfilled 405 nm acrylates indicate that the drop in tensile strength can exceed 15% when Z-axis specimens are printed at 0.100 mm layers without exposure compensation. Users should not transfer data from horizontally oriented specimens to vertically oriented load paths without destructive verification.

Heat deflection temperature under 0.455 MPa places the material below the typical service temperatures of injection-moulded ABS and polycarbonate. Continuous exposure to temperatures above 50 °C can produce creep under modest loads, and hot-air ageing above 60 °C may cause additional yellowing and embrittlement. Published data for this specific resin under long-term thermal ageing is limited.

Storage, cleaning, and post-exposure boundaries

The resin is not compatible with prolonged alcohol immersion. Cleaning of green-state parts is typically performed in 95% isopropyl alcohol using a short automated rinse, followed by compressed air drying. If a part is left in isopropyl alcohol for more than 10 min, edge softening can occur because uncured monomer and low-molecular-weight oligomers are extracted. Post-cure should be performed after drying. Residual alcohol on the surface can cause frosting or tacky surfaces. Parts built with 0.050 mm layers generally require a post-cure dose of 30 min to 60 min per orientation in a 405 nm chamber. Thicker sections do not automatically compensate for a lower cure dose.

Green-state parts before post-cure have limited strength and should be handled as partially polymerized structures. They are sensitive to room light, ambient oxygen inhibition, and thermal distortion. The build platform and vat should be cleaned with low-lint wipes and filtered back-flow to avoid pigment settling. The gray pigment package can settle during idle periods. The cartridge should therefore be shaken gently and the vat homogenised before restarting a build. High-shear mixing is not recommended because air entrainment creates voids that interfere with DLP recoating.

FabPro Proto GRY should not be combined with leftovers from other resin systems, particularly epoxy-based or cationic photopolymers. Residual acid or base species from those systems can disrupt radical polymerization and shift the working curve. Non-approved cleaning solvents such as acetone can attack cured parts and cause microcracking. Waste liquid is classified according to the safety data sheet, and disposal must follow local regulations for uncured acrylate monomers.

When dimensional verification replaces load-bearing end-use

FabPro Proto GRY should be selected for form-and-fit verification, visual concept approval, limited functional mock-ups, and master patterns in which component loads remain below the resin’s tensile yield envelope. The gray surface reduces glare and provides clear contrast for optical surface inspection and structured-light scanning. Surface finish after 0.050 mm layer printing is generally smooth enough for light sanding and primer without extensive filling. However, the material is not a rubber-like resin and not a high-impact resin. Snap-fit cantilevers with retained strain above 3% should be redesigned with larger radii or printed in FabPro Tough BLK. Thin walls below 1.0 mm should be evaluated for warpage and post-cure distortion. Section-thickness variation above 2.0 mm can create differential shrinkage and measurable flatness deviation.

Compared with FabPro Flex BLK, which is formulated for large recoverable strain, Proto GRY exhibits a distinct yield point and lower elongation. Compared with FabPro Tough BLK, whose datasheet reports higher notched Izod and elongation for snap-fit and clip applications, Proto GRY is not recommended for repetitive impact or high-strain assembly. The material also differs from castable resins in the FabPro family. Proto GRY is not formulated for investment-casting burnout and may leave refractory residue or ashing defects in the ceramic shell. Operators should not substitute Proto GRY for castable resin in jewellery or dental burnout workflows.

The resin is supplied for use in DLP systems with a 405 nm light engine. If a printer uses a 385 nm or 365 nm light source, cure depth and exposure reciprocity will shift, and the working curve should be recalibrated. Published data for this exact material on non-405 nm platforms is limited. The FabPro 1000 pixel spacing of 0.047 mm and vertical minimum layer of 0.025 mm define the practical resolution envelope. The resin does not increase resolution beyond the projector pixel limit.

For master patterns used in platinum-cure silicone tooling, the surface should be sealed because residual unreacted acrylate or photoinitiator may interfere with cure at the tool interface. A dry polytetrafluoroethylene release film or a one-part barrier coat is applied after full post-cure. Silicone inhibited at the contact surface is a common process failure when uncured resin species remain on the pattern. Operators should qualify the combination of pattern material, barrier coat, and silicone before committing a multi-cavity tool.