Abstract: This disclosure describes multi-fluid kits for three-dimensional printing, three-dimensional printing kits, and methods of testing powder bed material for contamination. In one example, a multi-fluid kit for three-dimensional printing can include a fusing agent and a detector solution. The fusing agent can include water, an electromagnetic radiation absorber, and a first pigment reactant. The electromagnetic radiation absorber can absorb radiation energy and convert the radiation energy to heat. The detector solution can include water and a second pigment reactant. The second pigment reactant can be reactive with the first pigment reactant to form a colored pigment.

Abstract: Examples of the present disclosure are directed toward methods and system for reducing surface roughness of a cured three-dimensional (3D) printed object using a localized heat source. An example method includes applying a liquid solvent to the cured 3D printed object and heating the cured 3D printed object with the liquid solvent applied thereto to a temperature below a melting point of the cured 3D printed object using a localized heat source to reduce a surface roughness of the cured 3D printed object as compared to the cured 3D printed object prior to the application of heat.

Abstract: A materials kit for three-dimensional (3D) printing can include a powder bed material including from about 60 wt % to 100 wt % composite fibers including glass fibers coated with an encapsulating polymer, wherein the composite fibers have an average length of from about 100 ?m to about 700 ?m and an average diameter of from about 20 ?m to about 70 ?m. The materials kit for 3D printing can also include a fusing agent including an energy absorber to absorb electromagnetic radiation to produce heat.

Abstract: This disclosure describes three-dimensional printing kits, methods, and systems for three-dimensional printing with directionally-dependent reflective particles. In one example, a three-dimensional printing kit can include a powder bed material and a fusing agent to selectively apply to the powder bed material. The powder bed material can include polymer particles and directionally-dependent reflective particles. The directionally-dependent reflective particles can be chemically and thermally stable at a melting point temperature of the polymer particles. The fusing agent can include water and a radiation absorber to absorb radiation energy and convert the radiation energy to heat.

Abstract: This disclosure describes three-dimensional printing kits, methods of making three-dimensional printed objects, and systems for three-dimensional printing. In one example, a three-dimensional printing kit can include a powder bed material and a fusing agent to selectively apply to the powder bed material. The powder bed material can include polymer particles and a redox-active inorganic salt mixed with the polymer particles. The fusing agent can include water and an electromagnetic radiation absorber, wherein the electromagnetic radiation absorber absorbs electromagnetic radiation energy and converts the electromagnetic radiation energy to heat.

Abstract: The present disclosure describes three-dimensional printing kits, methods of making three-dimensional printed objects, and three-dimensional printing systems. In one example, a three-dimensional printing kit can include a power bed material including thermoplastic polymer particles, a fusing agent to selectively apply to the powder bed material, and a post-processing agent to apply to a three-dimensional printed object. The fusing agent can include water and a radiation absorber that absorbs radiation and converts the radiation energy to heat. The post-processing agent can include a curable epoxy resin, where the epoxy resin, when cured, has a higher elastic modulus than the thermoplastic polymer particles.

Abstract: A three-dimensional printing system can include a build material including from about 95 wt % to 100 wt % of thermoplastic elastomer particles having a D50 particle size from about 2 ?m to about 150 ?m, and a printhead fluidly coupled to or fluidly coupleable to a fusing agent to selectively and iteratively eject the fusing agent onto successive placed individual layers thereof. The fusing agent can include water and a radiation absorber. The three-dimensional printing system can also include a radiant energy source positioned to expose the individual layers of the build material to radiation energy to selectively fuse the thermoplastic elastomer particles in contact with the radiation absorber to iteratively form a three-dimensional object including multiple layers of fused thermoplastic elastomer, and a heating device to heat the three-dimensional object to a temperature sufficient that layer-to-layer fusion at an interior location of the three-dimensional object is enhanced.

Abstract: A three-dimensional printed object can include a fused polyamide body having electromagnetic radiation absorber embedded as particles within the fused polyamide body, and the three-dimensional printed object can further include residual benzyl alcohol soaked into a surface of the polyamide body.

Abstract: The present disclosure describes multi-fluid kits for three-dimensional printing, three-dimensional printing kits, and systems for three-dimensional printing. In one example, a multi-fluid kit for three-dimensional printing can include a fusing agent, a solubilizing agent, and a detailing agent. The fusing agent can include water and an electromagnetic radiation absorber. The electromagnetic radiation absorber can absorb radiation energy and convert the radiation energy to heat. The solubilizing agent can include benzyl alcohol, an organic cosolvent, and water. The detailing agent can include a detailing compound.

Abstract: A three-dimensional printing formulation can include polymeric powder. The polymeric powder can include high aspect ratio composite particles including glass fibers coated with an encapsulating polymer in an amount from about 5 wt % to about 80 wt % based on a total weight of the polymeric powder, and low aspect ratio filler particles in an amount from about 20 wt % to about 95 wt % based on a total weight of the polymeric powder. The high aspect ratio composite particles can have an aspect ratio from about 7:1 to about 30:1 and the low aspect ratio filler particles can have an aspect ratio from 1:1 to less than 7:1.

Abstract: In an example of a surface treatment method, a three-dimensionally printed polyamide object is used. In the surface treatment method, the three-dimensionally printed polyamide object is first exposed to benzyl alcohol. In the surface treatment method, the three-dimensionally printed polyamide object is exposed to microwave irradiation after the benzyl alcohol exposure.

Abstract: An example of a multi-fluid kit for three-dimensional (3D) printing includes a fusing agent and a surface treating agent. The fusing agent includes an electromagnetic radiation absorber and a first aqueous vehicle. The surface treating agent includes a second aqueous vehicle, a surfactant, and benzyl alcohol dissolved in the second aqueous vehicle.

Abstract: The present disclosure includes a three-dimensional printing kit having a fusing agent with from about 75 wt % to about 99 wt % water, and from about 0.1 wt % to about 15 wt % radiation absorber. The three-dimensional printing kit can further include a polymeric build material including polyamide-12 particles, and a liquid oil comprising from about 50 wt % to 100 wt % of a long-chain molecule having a carbon chain of about C12 to about C100.

Abstract: A materials kit for 3D printing can include a powder bed material including from about 60 wt % to 100 wt % composite fibers having an average aspect ratio from about 3:1 to about 30:1 and a fusing agent including an energy absorber to absorb electromagnetic radiation to produce heat. The composite fibers can include glass fibers coated with an encapsulating polymer, wherein the glass fibers can be included at from about 5 wt % to about 40 wt % based on the total weight of the powder bed material.

Abstract: A method of recovering fluoropolymer from a three-dimensional printed object can include dissolving a fluoropolymer of a three-dimensional printed object in a fluoropolymer-dissolving solvent to generate dissolved fluoropolymer from the three-dimensional object, wherein the three-dimensional printed object includes from about 0.1 wt % to about 10 wt % particulate fusing compound and from about 90 wt % to about 99.9 wt % fluoropolymer. The method can further include separating the particulate fusing compound from the fluoropolymer-dissolving solvent and the dissolved fluoropolymer, and evaporating the fluoropolymer-dissolving solvent from the dissolved fluoropolymer.

Abstract: A method of recovering polyolefin polymer from a three-dimensional printed object can include dissolving a polyolefin polymer of a three-dimensional printed object in a polyolefin-dissolving solvent to generate dissolved polyolefin polymer from the three-dimensional object, wherein the three-dimensional printed object includes from about 0.1 wt % to about 10 wt% particulate fusing compound and from about 90 wt% to about 99.9 wt% polyolefin polymer. The method can further include separating the particulate fusing compound from the polyolefin-dissolving solvent and the dissolved polyolefin polymer, and evaporating the polyolefin-dissolving solvent from the dissolved polyolefin polymer.

Abstract: An example of a three-dimensional (3D) build material composition includes from about 70 wt % to about 95 wt % of polyamide particles, based upon a total weight of the build material composition; and from about 5 wt % to about 30 wt % of biodegradable polyester filler particles, based upon the total weight of the build material composition. The biodegradable polyester filler particles are present in the build material composition without any additional filler particles.

Abstract: A method of recovering polymer from a three-dimensional printed object can include dissolving a polyamide polymer of a three-dimensional printed object in a polyamide-dissolving solvent to generate dissolved polyamide polymer from the three-dimensional object, where the three-dimensional printed object can include a particulate fusing compound and from about 90 wt % to about 99.9 wt % of the polyamide polymer; separating the particulate fusing compound from the polyamide-dissolving solvent and the dissolved polyamide polymer; and evaporating the polyamide-dissolving solvent from the dissolved polyamide polymer.

Abstract: The present disclosure relates to a composition for printing a three-dimensional object. The composition comprises composite particles comprising a thermoplastic polymer and a colour-masking pigment. The colour-masking pigment is encapsulated by the thermoplastic polymer and is present in an amount of from about 1.5 to less than about 6 wt % of the total weight of the composite particles.

Abstract: A three-dimensional printing kit can include a powder bed material including from about 80 wt% to about 99.5 wt% thermoplastic elastomeric particles having a D50 particle size from about 2 µm to about 150 µm and from about 0.5 wt% to about 6 wt% C12-C24 straight-chain alkyl carboxylate. The three-dimensional printing kit can also include a fusing agent including water, organic co-solvent, and a radiation absorber to generate heat from absorbed electromagnetic radiation.