Proto3000 catalogue lists Formlabs White Resin V.4 as a 1 L cartridge-formulated opaque white photopolymer for low-force stereolithography on Formlabs Form 3, Form 3B, Form 3L, and Form 3BL systems. The material is part of the fourth-generation standard resin family and is identified by the code FLGPWH04. It is used where an opaque, light-scattering surface is required: dimensional validation of CAD geometry, assembly-fit fixtures, orthodontic and dental model bases, model-making, and enclosures that must block visible light. The resin carries no claim of biocompatibility, food-contact compliance, or high-temperature performance. Mechanical property values published by the supplier are generated from post-cured specimens printed and cured on Form 3-generation equipment and tested under ASTM methods. The resin cures under 405 nm illumination and supports layer-height settings of 25 µm, 50 µm, and 100 µm. The cartridge should be stored at 10–25 °C, and the printer environment should be maintained within 18–28 °C to avoid shifts in exposure latitude and pigment sedimentation.

Which Mechanical Property Values Define the Resin After Post-Curing?

The published values for White Resin V.4 are post-cure values, not green-state values. The standard post-cure cycle is 60 min at 60 °C in a Form Cure or Form Cure L unit. The table below summarises the values contained in the manufacturer’s mechanical data sheet; each value is tied to a test method.

The tensile elongation of 6.2 % places White Resin V.4 in a low-elongation class relative to engineering thermoplastics. The notched Izod value of 25 J/m indicates that thin ribs, snap features, and cantilevered tabs are vulnerable to crack propagation under sudden load. The difference between the two heat deflection temperatures is 14.7 °C; the lower value at 1.8 MPa should be used when the part is under sustained flexural load. The reported hardness of 87 Shore D is adequate for light contact surfaces but does not indicate wear resistance in abrasive contact. Because these values are generated on Form 3-generation equipment, parts printed on different stereolithography platforms or processed with non-standard post-cure may not reproduce the same results.

Before loading, the cartridge must be shaken thoroughly. White Resin V.4 contains white pigment that can settle during storage; an unshaken cartridge can deliver non-uniform pigment concentration through the resin feed system, producing visible streaks and variable opacity across the height of a build. The cartridge is then loaded into a Form 3, Form 3B, Form 3L, or Form 3BL system. The Form 3 build envelope is 145 × 145 × 185 mm; the Form 3L build envelope is 335 × 200 × 300 mm. These envelopes are printer-defined and are not altered by the resin. Layer height is selected in PreForm. A 25 µm layer height reduces stair-stepping on curved surfaces but increases build time compared with 50 µm and 100 µm layers. The resin is photocured at 405 nm through a flexible-film tank; the low-force process reduces peel force on fine features compared with rigid-tank bottom-up stereolithography. After printing, parts are washed in 99 % isopropyl alcohol for 20 min in Form Wash or Form Wash L. Incomplete washing leaves residual uncured monomer that remains tacky after curing and can interfere with dimensional measurement. After washing, parts are dried with compressed air and placed in a Form Cure or Form Cure L for 60 min at 60 °C. Support removal should follow the manufacturer’s orientation guidance; large flat sections may require additional low-density supports to prevent bowing during post-cure.

Surface finish is controlled primarily by layer height and part orientation. A 25 µm layer height produces lower stair-stepping than 100 µm layers on shallow slopes, but total build time increases approximately fourfold when layer thickness is reduced from 100 µm to 25 µm. Features on vertical walls show minimal stair-stepping; shallow angles below 30 ° from the build platform can show visible terraces regardless of resin colour. White pigmentation tends to make stair-stepping more visible under oblique lighting than clear or grey resins because of increased diffuse reflectance. Sanding or bead blasting is possible, but the material is low-elongation and thin edges can chip when mechanically finished.

Thermal Deflection and Anisotropy Under Different Post-Cure Durations

The polymer network reaches design properties only after thermal post-cure. The published 0.45 MPa heat deflection temperature of 73.1 °C indicates short-term thermal resistance, not continuous service temperature. For parts carrying mechanical load, the 1.8 MPa value of 58.4 °C is more relevant. Continuous exposure above 50 °C can produce creep and dimensional relaxation in loaded sections. Under-curing below 60 min at 60 °C leaves residual monomer and lower crosslink density, which depresses tensile modulus and increases solvent sensitivity. Extended post-cure beyond 120 min can embrittle thin walls and shift the white colour toward ivory; published data for this specific configuration is limited, so extended cycles should be validated with in-house tensile coupons. Layerwise photopolymerisation introduces anisotropy: Z-oriented specimens typically display lower elongation and tensile strength than XY-oriented specimens. For critical load paths, design should orient primary tensile stresses in the XY plane or replace White Resin V.4 with a resin having higher toughness. The low notched Izod value of 25 J/m makes the material unsuitable for repeated flexure, snap-fit closures, and threaded fasteners that generate high insertion strain.

White Resin V.4 shares the general-purpose standard tier with Clear Resin V.4 and Grey Resin V.4. The primary difference is optical: the white variant scatters visible light, while Clear Resin V.4 transmits it for fluidic observation or transparent prototyping. In mechanical terms, the standard resin family is below Tough 2000 Resin in elongation and impact resistance; Tough 2000 is selected for snap-fit assemblies and parts subjected to transient loads. High Temp Resin V.2 is specified for thermal loads because its published heat deflection temperature at 1.8 MPa exceeds 200 °C; White Resin V.4 is not a substitute in heated jigs or soldering fixtures. Rigid 10K Resin provides a higher flexural modulus for mould inserts and dimensionally stable tooling, whereas White Resin V.4 is intended for general visual and dimensional prototypes. Compared with Durable Resin, White Resin V.4 has lower elongation and lower impact behaviour; Durable Resin is used where parts must resist cyclic deformation. Compared with Grey Resin V.4, the white pigment affords stronger visual contrast for scanning and feature inspection, but the two are otherwise positioned in the same mechanical category. Selection between them is optical rather than mechanical.

When White Resin V.4 Replaces Clear Resin V.4 in Opaque Fit-Check Fixtures

When an assembly fixture requires light blocking or a matte white background for optical inspection, White Resin V.4 replaces Clear Resin V.4 without a mechanical downgrade because both belong to the same standard resin family. The white pigment reduces transmitted light and improves contrast for machine-vision systems that rely on diffuse reflection. The fixture surfaces should be lightly bead-blasted or left as-printed to reduce specular reflection; the opaque white colour alone does not eliminate gloss from 25 µm layers. In inspection setups, direct contact with isopropyl alcohol should be limited to the wash cycle, and prolonged solvent exposure should be avoided because the cured network is susceptible to solvent swelling. For fixtures that are exposed to repeated handling, the low impact resistance should be assessed with an assembly force evaluation; press-fit features should be evaluated for low insertion strain because of the notched Izod value of 25 J/m. Large solid sections should be hollowed with adequate drain holes to prevent trapped uncured resin from generating internal pressure during wash and cure. The resin is not a substitute for Clear Resin V.4 in applications requiring optical transparency; conversely, Clear Resin V.4 is not a replacement for White Resin V.4 when visible-light opacity is a functional requirement.

Dimensional accuracy of White Resin V.4 parts is not a single resin property; it emerges from the interaction of layer height, build orientation, support placement, wash time, cure schedule, and ambient humidity. The Form 3/3B/3L/3BL optical resolution is 25 µm in XY, but resin shrinkage during photopolymerisation introduces additional deviation. Photopolymers typically exhibit volumetric shrinkage on the order of 1–4 %; the flexible-tank LFS process reduces peel-induced displacement, but residual stress remains locked into the part until stress relief during post-cure. For close-fitting assembly parts, allowances of at least 0.1 mm per mating surface are common, but published data for this specific configuration is limited. Iterative printing with test coupons is required to establish a local tolerance band. The resin’s opacity assists in optical metrology because white surfaces reduce translucency-related scanning artefacts that can occur with clear materials.

The uncured resin is a skin and eye irritant; nitrile gloves and chemical goggles are required during cartridge loading, part removal, and wash operations. The liquid resin should not be poured back into the cartridge after exposure to isopropyl alcohol or other contaminants because solvent dilution changes viscosity and polymerisation kinetics. The cartridge should be stored upright in a dark, sealed condition at 10–25 °C; the manufacturer lists a shelf life of 24 months for unopened cartridges. Freezing causes phase separation and pigment flocculation; if a cartridge is exposed to low temperature, it must be returned to room temperature and shaken before printing. Post-cured parts are not food-contact approved and should not be used in continuous skin contact or intraoral applications unless processed with a validated biocompatible dental resin. Long-term exposure to water, ketones, esters, chlorinated solvents, and strong alkaline solutions causes swelling and loss of dimensional stability; the material also degrades under outdoor UV exposure. These boundaries are operational limits, not printable design constraints. Parts that must operate outside these limits require a different resin class. The product is therefore positioned as a general-purpose opaque white material for controlled indoor prototyping and non-load-bearing visual or dimensional models.