Selective laser sintering (SLS) and HP's Multi Jet Fusion (MJF) both make plastic parts by fusing nylon or other polymer powder in a heated bed. In both, the loose powder around each part holds it in place, so neither prints support structures. The difference is how energy reaches the powder. An SLS printer scans a laser across each cross-section. An MJF printer jets liquid agents across the layer and then heats the whole layer with lamps. Stratasys' Selective Absorption Fusion (SAF) is a third approach that also jets a fluid and fuses with infrared light.
Most published comparisons come from companies that sell one of these processes, so the figures on this page are attributed to their sources. For the wider powder bed fusion family, including metal, see the powder bed fusion explainer.
How SLS applies heat
Formlabs explains that an SLS printer preheats the powder to a little below the polymer's melting point, so the laser only has to add a small amount of energy where the part should form. The powder and the partly built parts must stay within about 2 °C through preheating, sintering and storage to limit warping, and the platform drops 50 to 200 microns per layer. Because the laser sinters each cross-section point by point, as HP's process comparison notes, the time per layer grows with the area being fused. When the build ends, the whole block of powder has to cool before parts come out, which Formlabs says can take up to half the print time.
How MJF and SAF apply heat
In MJF, an inkjet array deposits a fusing agent where the part should be and a detailing agent around its edges, then fusing lamps heat the layer. HP says this lets the printer process a complete layer at the same time. A 2025 review of PA6 and PA12 printing by Kohutiar and colleagues argues that heating a whole layer with infrared energy gives more uniform melting and crystallization than a point laser, which it says can cause local overheating.
Stratasys says SAF uses industrial print heads to apply a fusing fluid that increases the powder's absorption of heat, after which an infrared lamp fuses the layer. It sells the process on its H350 printer and claims builds can be nested above 40 percent of the volume without quality problems. Formlabs, which sells SLS printers, notes that SLS originated at the University of Texas at Austin and that HP introduced MJF in 2016.
Powder reuse and refresh rates
In every one of these processes, the unfused powder sits at high temperature for the whole build and degrades slightly, so recovered powder is mixed with fresh powder before the next job. Two numbers decide how much powder you buy: the share of fresh powder each job needs, called the refresh rate, and how densely parts are packed in the build. Formlabs puts typical SLS at about 30 percent fresh powder and MJF at about 20 percent, but says MJF builds are usually packed at only 8 to 10 percent, which leaves much more surplus powder than the parts use. It claims its own Fuse printers pack above 30 to 40 percent and can reuse all of the unsintered powder from a fully packed build.
HP's product comparison lists up to 80 percent powder reusability on the Jet Fusion 5200 and up to 75 percent on the 5420W, which prints white parts. Stratasys claims up to 100 percent powder use for SAF. Each vendor measures under its own conditions, so ask a printer seller or service bureau for refresh rates and packing densities for the exact material you plan to use.
Surface, color and materials
Both processes leave a slightly grainy, matte surface with almost no visible layer lines, and Formlabs says engineers don't usually tell SLS and MJF apart by texture. Color is the clearer difference. EOS, which sells SLS printers, says SLS is the only technology that produces truly white parts and that MJF parts come out gray, so deep blacks or brand colors need an extra dyeing step. HP's own lineup lists gray parts from most Jet Fusion models, light gray with one material on the 5600, and white from the 5420W. Formlabs adds that full-color MJF exists but only on more expensive systems.
Materials overlap heavily. Formlabs says both processes run mostly nylon, with nylon 12 the most common. HP lists nylon 11, several nylon 12 grades including glass-bead-filled and flame-retardant versions, polypropylene and TPU across its current printers. Stratasys lists PA11, PA12 and polypropylene for SAF. EOS argues that SLS gives engineers more material options than MJF.
Part properties and throughput
For nylon 12, the figures Formlabs compiled show similar tensile strength across processes: 50 MPa for its Fuse 1+ 30W, 48 MPa for EOS PA 12 and 48 MPa for HP MJF PA 12, with elongation at break of 11, 18 and 20 percent respectively. Formlabs calls the two processes virtually identical in how evenly they perform in every direction. The Kohutiar review leans toward MJF, citing studies that found higher density and lower porosity in MJF parts, but it also stresses that properties depend on print orientation and processing parameters.
On speed, HP claims breakthrough productivity for MJF, and Formlabs agrees that MJF generally out-produces large laser systems because it processes a whole layer at once. HP's comparison gives full-build print times of 9.4 to 13.5 hours on its Jet Fusion 5200, depending on print mode. Cooling is part of the cycle for both. Formlabs says large SLS and MJF machines can need up to 48 hours to cool and that HP sells a refrigeration option to speed this up.
Build sizes overlap. HP lists an effective build volume of 380 × 284 × 380 mm for its Jet Fusion 5200 and 5600. Formlabs gives 165 × 165 × 300 mm for its benchtop Fuse 1+ 30W and 330 × 330 × 565 mm for the Fuse X1, and cites EOS SLS systems ranging from 200 × 250 × 330 mm to 700 × 380 × 580 mm.
| Factor | SLS | MJF | SAF |
|---|---|---|---|
| How energy is applied | A laser scans each cross-section in a preheated bed | Fusing and detailing agents are jetted, then lamps heat the layer | A fusing fluid is jetted, then an infrared lamp fuses the layer |
| Example suppliers | Formlabs, EOS | HP | Stratasys |
| Color as printed | White possible, per EOS | Gray on most HP models; white on the 5420W | Not stated by Stratasys |
| Powder reuse claims | About 30% fresh powder per job is typical, per Formlabs | About 20% fresh, per Formlabs; up to 80% reusability, per HP | Up to 100% powder use, per Stratasys |
| Materials cited | Nylon 12, nylon 11, TPU and filled nylons | Nylon 11 and 12, polypropylene, TPU | PA11, PA12, polypropylene |
| Example build volume | 165 × 165 × 300 mm (Fuse 1+ 30W) to 700 × 380 × 580 mm (largest EOS system, per Formlabs) | 380 × 284 × 380 mm (HP Jet Fusion 5200 and 5600) | Not given in these sources |
| Printer price, per Formlabs | From about $30,000 benchtop; about $200,000 and up for traditional systems | About $350,000 to more than $600,000 | Not given in these sources |
At a glance
Strengths
- Choose SLS when parts must be white or you want the widest choice of powders, per EOS
- Choose SLS to bring powder printing in-house on a smaller budget, with benchtop machines from about $30,000 per Formlabs
- Choose MJF for high throughput on full builds, since each layer is processed at once
- Choose SAF when polypropylene parts or high nesting density matter, per Stratasys
Limitations
- SLS: layer time grows with fused area, so large full builds take longer
- MJF: parts usually come out gray and need dyeing for most colors, per EOS
- MJF: industrial systems cost about $350,000 to more than $600,000, per Formlabs
- All three: long cooling times and powder refresh to manage
Typical applications
- Functional nylon prototypes and end-use parts in any of the three processes
- MJF: end-of-arm tooling, robotics, medical devices, dental aligner molds and automotive parts, per HP
- SLS: parts that need a white finish, per EOS
- SAF: chemically resistant and airtight polypropylene parts, per Stratasys
Materials for this process
Common questions
Is MJF stronger than SLS?
Not by much, according to the published figures. Formlabs' nylon 12 comparison lists 50 MPa tensile strength for its Fuse SLS printer and 48 MPa for both EOS SLS and HP MJF. A 2025 review by Kohutiar and colleagues cites studies finding MJF parts denser and less porous, but notes that results depend on orientation and process settings.
Can MJF print white or colored parts?
Most HP Jet Fusion printers make gray parts that are dyed or painted for color. HP lists white parts from the Jet Fusion 5420W with its PA 12 W material and light gray from one material on the 5600. Formlabs says full-color MJF is available only on more expensive systems.
What is Stratasys SAF?
Selective Absorption Fusion is Stratasys' powder bed process. Print heads apply a fusing fluid that makes the powder absorb more heat, and an infrared lamp fuses each layer. Stratasys offers PA11, PA12 and polypropylene on its H350 printer and claims nesting above 40 percent and up to 100 percent powder use.
How much powder is wasted in SLS and MJF?
It depends on the refresh rate and how tightly the build is packed. Formlabs cites about 30 percent fresh powder for typical SLS and about 20 percent for MJF, with MJF builds often packed at only 8 to 10 percent. HP claims up to 80 percent reusability on the Jet Fusion 5200. Ask for figures measured on your material.
Sources
- Selective Laser Sintering (SLS): Complete Guide Formlabs · Checked 2026-10-15
- Comparing Binder jetting, Material Jetting, Multi Jet Fusion and SLS HP · Checked 2026-11-02
- Comprehensive Review: Technological Approaches, Properties, and Applications of Pure and Reinforced Polyamide 6 (PA6) and Polyamide 12 (PA12) Composite Materials (Kohutiar et al., Polymers, 2025) Polymers (MDPI) via PubMed Central · Checked 2026-11-02
- SAF Technology (Selective Absorption Fusion) Stratasys · Checked 2026-11-02
- MJF vs SLS: Plastic Powder Bed Fusion 3D Printers Comparison Formlabs · Checked 2026-11-02
- Compare the MJF 3D Printers HP · Checked 2026-11-02
- What Is A Powder Printer? How Powder 3D Printing Is Changing the Manufacturing Landscape EOS · Checked 2026-11-02
An explainer synthesized from the cited references, not hands-on testing. Vendor names for processes are trademarks of their owners and are mapped to the ISO/ASTM 52900 families for orientation.