Abstract: In an example of a method for three-dimensional (3D) printing, a polymeric build material is applied to form a build material layer. A fusing agent is selectively applied, based on a 3D object model, onto the build material layer to form a patterned portion. A hydrophilic agent is selectively applied, based on the 3D object model, onto at least a portion of the patterned portion. The hydrophilic agent includes from 1 wt % to 12 wt % of a hydrophilic polymer dissolved in an aqueous liquid vehicle, wherein the hydrophilic polymer has a molar mass ranging from 1000 g/mol to 12,000 g/mol and is water-absorbent at a water to hydrophilic polymer weight ratio from 2:1 to 1000:1. The build material layer is exposed to energy to selectively coalesce the patterned portion and form a 3D object layer having a hydrophilic portion.

Abstract: In an example of a method for three-dimensional (3D) printing, a polymeric build material is applied to form a build material layer. A fusing agent is selectively applied, based on a 3D object model, onto the build material layer to form a patterned portion. A hydrophobic agent is selectively applied, based on the 3D object model, onto at least a portion of the patterned portion. The hydrophobic agent includes a lipophilic phase discontinuously dispersed within an aqueous phase by a surfactant, wherein the lipophilic phase includes an organosilane having a central silicon atom coupled to a C6 to C24 aliphatic or alicyclic hydro-carbon and multiple hydrolyzable groups, wherein the organosilane is present in the hydrophobic agent at from about 1 wt % to about 20 wt %. The build material layer is exposed to energy to selectively coalesce the patterned portion and form a 3D object layer having a hydrophobic portion.

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: A multi-fluid kit for three-dimensional printing can include a fusing agent comprising water and a radiation absorber, wherein the radiation absorber absorbs radiation energy and converts the radiation energy to heat. The multi-fluid kit can also include a detailing agent including an aqueous liquid vehicle and from about 1 wt % to about 12 wt % polyelectrolyte solubilized in the aqueous liquid vehicle at from about 90 wt % to 100 wt %. The polyelectrolyte can have a weight average molecular weight from about 1,000 Mw to about 12,000 Mw and can be water-absorbent at a water to polyelectrolyte weight ratio from about 2:1 to about 1,000:1.

Abstract: An example of a kit for 3D printing includes a build material composition and a fusing agent to be applied to at least a portion of the build material composition during 3D printing. The build material composition of the kit includes a polyamide 6,13 material, a phosphorus-containing antioxidant, and a sulfur-containing antioxidant, or a polyamide 6 material, the sulfur-containing antioxidant, and a phenolic antioxidant. The fusing agent includes a radiation absorber to absorb radiation to melt or fuse the build material composition in the at least the portion.

Abstract: This disclosure describes three-dimensional printing kits, methods, and systems for three-dimensional printing with scent additives. 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 scent additive. The scent additive can be chemically 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: The present disclosure is drawn to three-dimensional printing kits, methods of making magnetic three-dimensional printed articles, and systems for three-dimensional printing. In one example, a three-dimensional printing kit can include a powder bed material, a fusing agent, and a magnetic agent. The powder bed material can include polymer particles. The fusing agent can include water and a non-magnetic radiation absorber. The non-magnetic radiation absorber can absorb radiation energy and convert the radiation energy to heat. The magnetic agent can include a dispersion of magnetic nanoparticles.

Abstract: An example of an ultraviolet (UV) light fusing agent for three-dimensional (3D) printing includes a vehicle and a multi-functional antioxidant and UV light absorber dispersed in the vehicle. The vehicle includes water and a water miscible or water soluble organic solvent. The multi-functional antioxidant and UV light absorber includes a metal oxide particle that is to absorb UV radiation having a wavelength within a range from about 330 nm to about 405 nm and a passivating agent complexed with at least a portion of a surface of the metal oxide.

Abstract: This disclosure relates to a material set including a build material for 3-D printing including particles of a polymer comprising polymer chains having at least one reactive group that is protected with a protecting group. The material set further includes an inkjet composition including a de-protecting agent for removal of the protecting group, and a liquid carrier.

Abstract: An example of a three-dimensional (3D) printing kit includes a build material composition and a fusing agent to be applied to at least a portion of the build material composition during 3D printing. The build material composition includes a polyamide having: an avalanche angle ranging from about 35 degrees to about 55 degrees; a break energy ranging from about 25 kJ/kg to about 57 kJ/kg; and an avalanche energy ranging from about 7 kJ/kg to about 22 kJ/kg. The fusing agent includes an energy absorber to absorb electromagnetic radiation to coalesce the polyamide in the at least the portion.

Abstract: An example of an anti-coalescing agent for a three-dimensional (3D) printing process includes a vehicle and an anti-coalescing polymer dispersed in the vehicle. The vehicle includes a co-solvent, a surfactant, a humectant, and water. The anti-coalescing polymer has a mean particle size ranging from about 50 nm to about 195 nm, and the anti-coalescing polymer is to coat polymeric build material particles to prevent the polymeric build material particles from coalescing during electromagnetic radiation exposure of the 3D printing process.

Abstract: The present disclosure describes multi-fluid kits for three-dimensional printing, three-dimensional printing kits, and methods of making three-dimensional printed articles. In one example, a multi-fluid kit for three-dimensional printing can include a fusing agent and a second fluid agent. The fusing agent can include water, a polar organic solvent having a boiling point from about 200° C. to about 320° C., and a radiation absorber. The radiation absorber can absorb radiation energy and convert the radiation energy to heat. The fusing agent or the second fluid agent can include a dihydrazide antioxidant.

Abstract: The present disclosure describes multi-fluid kits for three-dimensional printing, materials kits for three-dimensional printing, and methods of making three-dimensional printed articles. In one example, a multi-fluid kit for three-dimensional printing can include a fusing agent and a pore-promoting agent. The fusing agent can include water and a radiation absorber. The radiation absorber can absorb radiation energy and convert the radiation energy to heat. The pore-promoting agent can include water and a water-soluble pore-promoting compound. The pore-promoting compound can chemically react at an elevated temperature to generate a gas.

Abstract: An example of a three-dimensional (3D) printing kit includes a build material composition and a fusing agent to be applied to at least a portion of the build material composition during 3D printing. The build material composition includes a polyamide having a melt enthalpy ranging from greater than 5 J/g to less than 150 J/g. The fusing agent includes an energy absorber to absorb electromagnetic radiation to coalesce the polyamide in the at least the portion. The fusing agent is a core fusing agent and the energy absorber has absorption at least at wavelengths ranging from 400 nm to 780 nm; or the fusing agent is a primer fusing agent and the energy absorber is a plasmonic resonance absorber having absorption at wavelengths ranging from 800 nm to 4000 nm and having transparency at wavelengths ranging from 400 nm to 780 nm.

Abstract: An example of a build material composition for three-dimensional (3D) printing includes a polyamide material and an antioxidant. The antioxidant consists of an aromatic multihydrazide; or an aromatic sulfonomonohydrazide; or a hydrazide having formula (I) disclosed herein, wherein: R is null, a C1 to C12 unbranched alkyl, a C3 to C8 branched alkyl, a C2 to C8 unbranched alkylene, a C4 to C8 branched alkylene, an alicyclic compound, a polyethylene glycol, or a combination thereof; A is C?O, O?S?O, P?O, or C?S; and n is an integer ranging from 1 to 4; or formula (II) disclosed herein wherein A is C?O, O?S?O, P?O, or C?S.

Abstract: An example of a build material composition for three-dimensional (3D) printing includes a polyamide material and an antioxidant. The antioxidant includes an aromatic multihydrazide; or an aromatic sulfonomonohydrazide; or a hydrazide having formula (I) disclosed herein, wherein: R is null, a C1 to C12 unbranched alkyl, a C3 to C8 branched alkyl, a C2 to C8 unbranched alkylene, a C4 to C8 branched alkylene, an alicyclic compound, a polyethylene glycol, or a combination thereof; A is C?O, O=S?O, P?O, or C?S; and n is an integer ranging from 1 to 4; or formula (II) disclosed herein wherein A is C?O, O?S=O, P?O, or C?S.

Abstract: This disclosure relates to a method of 3-D printing comprising: applying a layer of build material onto a print platform, wherein the build material comprises particles of a polymer comprising polymer chains having at least one reactive group that is protected with a protecting group; printing a de-protecting agent at selected locations on the layer of build material; and coalescing particles of the polymer at the printed locations on the layer of build material to form a coalesced polymer layer.

Abstract: An example of a three-dimensional (3D) printing kit includes a build material composition and a fusing agent to be applied to at least a portion of the build material composition during 3D printing. The build material composition includes a polyamide having: an avalanche angle ranging from about 35 degrees to about 55 degrees; a break energy ranging from about 25 kJ/kg to about 57 kJ/kg; and an avalanche energy ranging from about 7 kJ/kg to about 22 kJ/kg. The fusing agent includes an energy absorber to absorb electromagnetic radiation to coalesce the polyamide in the at least the portion.

Abstract: An example of a three-dimensional (3D) printing kit includes a build material composition and a fusing agent to be applied to at least a portion of the build material composition during 3D printing. The build material composition includes a thermoplastic elastomer having: an avalanche angle ranging from about 49 degrees to about 59 degrees; a break energy ranging from about 55 kJ/kg to about 78 kJ/kg; and an avalanche energy ranging from about 10 kJ/kg to about 27 kJ/kg. The fusing agent includes an energy absorber to absorb electromagnetic radiation to coalesce the thermoplastic elastomer in the at least the portion.

Abstract: An example of a three-dimensional (3D) printing kit includes a build material composition and a fusing agent to be applied to at least a portion of the build material composition during 3D printing. The build material composition includes thermoplastic elastomer particles, wherein at least 70% of the thermoplastic elastomer particles, based on a number distribution, have an aspect ratio ranging from 0.75 to 1. The fusing agent includes an energy absorber to absorb electromagnetic radiation to coalesce the thermoplastic elastomer particles in the at least the portion.