3D Systems Accura e-Stone™ PEACH Plastic for SLA Systems is a filled, peach-pigmented stereolithography photopolymer formulated for laser-cure additive manufacturing on 3D Systems SLA platforms operating at 355 nm. The resin is not an unfilled acrylate or an epoxy-only system; its dispersed mineral phase raises post-cure modulus and reduces creep relative to unfilled resins in the Accura product line. Typical build configurations reported for this resin include 0.100 mm and 0.125 mm layer thickness settings on ProX 800-class systems, although the actual z-resolution is governed by machine-specific recoating parameters and the operator’s validated process window. The peach pigmentation serves as a grade identifier and visual contrast aid during finishing. Mechanical characterization is referenced to ASTM D638-14 and ASTM D790-17; single-point datasheet values are not reproduced here because post-cure dose, part orientation, and wall thickness produce property scatter that cannot be reduced to one fixed nominal value without losing production context.

Which Post-Cure Dose Limits Warpage in Thin-Walled Wax Substitutes?

Thin-walled casting patterns produced from Accura e-Stone PEACH are sensitive to the secondary UV post-cure dose. Under-cured sections retain unreacted monomer that can continue to polymerize during storage, producing slow linear shrinkage and out-of-plane warpage. Over-curing generates excessive crosslink density and residual surface stress, which manifests as concave distortion on walls below 1.0 mm thickness. The process window is established by measuring green-state and post-cured dimensions on a machined reference coupon rather than by relying on visual surface finish. Heat deflection temperature is evaluated under ASTM D648-18 at both 0.46 MPa and 1.82 MPa flexural stress; the lower-stress condition is more relevant to shell de-waxing and low-pressure tooling heat exposure. Flexural modulus is evaluated under ASTM D790-17 or ISO 178, and tensile testing under ASTM D638-14 or ISO 527-2. When a pattern includes unsupported spans, the effective stiffness after post-cure determines whether the pattern survives shell building without breakage.

The resin’s mixed filler system affects recoat behavior differently from unfilled Accura grades. On high-speed recoat platforms, prolonged idle periods permit filler migration toward the vat bottom. Agitation is required before initiating a build after downtime exceeding 8 h. Viscosity stratification can produce a low-modulus upper layer that under-cures at the same laser exposure, followed by a high-solids lower layer that increases blade resistance. Operators using ProX 800 systems with wiper-based recoating report that changes in recoat force trace are an early indicator of filler settling. The recoat speed and blade gap are locked to the validated process rather than adjusted for apparent surface gloss. Batch-to-batch variation in filler particle size can shift the liquid resin’s viscosity and the cured material’s impact sensitivity; an incoming viscosity check under ISO 2884 is a practical release test.

When Lower Incineration Residue Is Required for Shell Casting Transfer

Accura e-Stone PEACH is not a direct substitute for Accura CastPro in every investment casting workflow. CastPro is formulated for low residual ash after shell burnout and has published burnout profiles developed for dental and industrial casting shells. Accura e-Stone PEACH is positioned for pattern stock that requires higher green-state rigidity and better handling damage resistance during shell face-coat application. The mineral filler that contributes stiffness can leave a higher incineration residue than unfilled casting-specific resins. For shell systems operating below 700 °C burnout, published data for this specific configuration is limited, and a production-scale burnout trial should be performed before changing pattern material. Where the pattern is used only for room-temperature vulcanizing silicone tooling, low-ash performance is not the controlling selection criterion. Differences from Accura 25 are also significant: Accura 25 is an unfilled, polypropylene-like SLA material with higher elongation and lower stiffness, while Accura e-Stone PEACH exhibits higher rigidity and is less appropriate for snap-fit or high-strain applications.

Surface finishing operations on Accura e-Stone PEACH require coolant or low-pressure dry cutting because the filled polymer behaves as a brittle solid under high-speed steel tooling. Rotary tools with carbide burrs and high spindle speeds generate local heat that can cause surface chalking and microcracking. Wet sanding with 600-grit followed by 1000-grit paper is used to remove build layers without excessive material removal. Grit blasting with glass bead at 0.2–0.4 MPa is an alternative for matte texture, but sharp-edge erosion is a measured risk on thin walls. Pattern sealing is required before silicone molding because the cured surface contains residual uncured monomer and open pores along layer boundaries. A two-part polyurethane or epoxy sealer with no amine catalyst is applied after cleaning. Amine-based mold rubbers and epoxy hardeners can attack the pattern surface and should be avoided unless compatibility testing shows no softening after 24 h contact.

Dimensional Stability and Moisture Uptake in Humid Pattern Storage

Accura e-Stone PEACH is conditioned at 23 ± 2 °C and 50 ± 10% relative humidity in accordance with ISO 291 before dimensional verification. Water absorption is evaluated by ASTM D570-98(2021), and absorbed moisture can expand the filled polymer matrix enough to affect tight tooling fits. Storage above 60% RH for extended durations may increase surface tack and reduce the effective hardness; desiccant drying at 30 °C for 24–48 h restores measurable hardness in most production cases, but the dimensional change is not always fully reversible. Pattern designers incorporate a volumetric compensation factor derived from measured linear shrinkage on the machine, oven, and post-cure cycle. This value is not a fixed material property; it varies with part size, wall thickness, and build orientation. Layer-adhesion anisotropy also produces lower tensile strength in the Z-direction than in the X-Y plane, which is considered when the pattern is loaded perpendicular to build layers.

The resin’s operational boundaries include a narrow usable temperature window during cleaning. Solvent immersion in isopropanol above 25 °C can cause swelling and edge softening, especially on thin sections. Tripropylene glycol monomethyl ether is the preferred cleaning solvent for filled SLA grades because its lower evaporation rate and solvency reduce surface stress cracking. After cleaning, forced-air drying is mandatory before UV post-cure; residual solvent in the polymer network can cause micro-voids. The post-cure chamber provides uniform UVA exposure; a non-uniform chamber yields variable crosslink density and scatter in mechanical test results exceeding 10% coefficient of variation across the build platform. For full compliance documentation, users reference the 3D Systems material data sheet for Accura e-Stone PEACH and the equipment installation qualification records for the specific SLA system. When used in investment casting, the pattern is evaluated for shell cracking due to thermal expansion mismatch; published data for this specific configuration is limited for shell systems at high heating rates.

Accura e-Stone as a Master Pattern for RTV Silicone Tooling

For master patterns used in room-temperature vulcanizing silicone tooling, Accura e-Stone PEACH combines high rigidity with low creep under vacuum pressure. The pattern surface is sealed after finishing because the layer interface can absorb silicone oil and plasticizer. A thin solvent-borne epoxy or two-part polyurethane sealer is applied in 2 coats by spraying, with flash-off at 20 °C. If the sealer contains volatile organic compounds, full outgassing before mold pouring is required to avoid bubble formation at the pattern surface. The silicone mold material is addition-cure platinum-catalyzed type; tin-catalyzed condensation-cure systems may release alcohol byproducts that interact with the sealer. A release agent based on a non-amine polymer film is applied at 0.2 μm dry thickness. In production-scale vacuum casting, the pattern is checked for dimensional movement after each molding cycle because repeated vacuum pulls can induce small creep deformation in thin walls below 2.0 mm.

On a 3D Systems ProX 800 with a frequency-tripled solid-state laser operating near 355 nm, the exposure strategy for Accura e-Stone PEACH is adjusted using critical exposure and cure depth data obtained from the resin’s working curve. The operator does not reuse the exposure settings from Accura 25 or Accura ClearVue because the filled resin’s higher viscosity and optical scattering shift the cure depth at equivalent laser dose. Beam compensation and alternate hatch spacing are determined from a pixel-based calibration grid built at the intended layer thickness. The build platform temperature is maintained within the machine manufacturer’s specified band, typically 28–32 °C, during printing; temperatures outside this band affect viscosity and recoat quality. Once the laser power is verified with a power meter traceable to the machine manufacturer, the energy is normalized to the build area and the scanning speed is set to produce the required dose per layer. Records of laser power, recoat force, and room humidity are retained as part of the machine qualification for each material lot.

Accura e-Stone PEACH is stored in sealed, moisture-tight containers to prevent humid air from degrading the unreacted resin. Storage temperatures below 4 °C extend liquid resin shelf life, but the material is conditioned to 20–25 °C before loading into the SLA vat. Frozen or cold resin should not be introduced directly to a heated vat because thermal shock can induce temporary viscosity stratification and recoat defects. The resin is not compatible with solvent-based cleaning agents containing chlorinated hydrocarbons or strong alkalines; these agents can attack the cured surface and alter the peach-colored outer layer. When changing from another Accura resin in a shared vat, a full vat drain and clean is performed because cross-contamination between filled and unfilled formulations can shift both viscosity and photopolymerization behavior. Disposal of uncured resin, cleaning solvents, and post-cure wash solutions follows the supplier’s safety data sheet and local regulatory requirements under REACH and RoHS where applicable. The material has no documented food-contact approval under FDA 21 CFR 177.1550, and it is not specified for medical implant or long-term skin-contact devices without additional biocompatibility testing.