Giving powder a second life: how to reuse MJF PA12 in SLS printing on Lisa X

As the 3D printing industry continues to mature, sustainable practices are gaining momentum across all sectors. Among these, the reuse of powdered materials from Multi Jet Fusion (MJF) technology in Selective Laser Sintering (SLS) processes stands out as a promising approach to reduce waste and cost while maintaining high print quality. This article delves into the process and advantages of reusing HP’s used PA12 powder from MJF machines in the SLS process on Sinterit’s Lisa X printer.

The context: why reuse MJF powder?

Multi Jet Fusion, developed by HP, is a high-speed powder-based 3D printing technology popular in industrial applications for its speed, detail, and mechanical properties. However, not all powder is fused in each print job. While HP promotes the use of their “High Reusability PA12” line, in practice, even reusability comes with limits.

Typically, only a portion of the powder can be reused directly in subsequent MJF prints. The rest — known as “used” or “spent” powder — often gets discarded, despite still having viable thermal and flow characteristics. Enter SLS printing: particularly with open-platform systems like the Sinterit Lisa X, this leftover powder can be given a second life.

Compatibility considerations

Before diving into the reuse process, it’s critical to understand which HP powders are compatible with this method. Not all MJF powders are suitable for reuse in SLS.

✅ Compatible powders:

• HP 3D High Reusability PA 12 (for Jet Fusion 4200/5200)
• HP 3D High Reusability CB PA 12 (for Jet Fusion 500/300)

❌ Not compatible:

• HP 3D High Reusability PA 12 W39 (for Jet Fusion 5420)

How the conditioning process works

Used PA12 powder from HP’s Multi Jet Fusion process can be effectively refreshed for SLS printing on the Lisa X through a precise and controlled mixing process. The procedure begins by measuring out 8 kilograms of used powder and blending it with 56 grams of a carbon additive to restore flowability and thermal consistency. A small portion of the powder (2 kg) is first sifted together with the carbon to create a uniform premix, which is then blended thoroughly. This premix is combined with the remaining 6 kilograms of powder, sifted beforehand to ensure consistency, and mixed in a high-speed powder mixer for an hour. Afterwards, the entire batch is sifted again and given a final 15-minute blend to achieve optimal homogeneity. Once ready, the refreshed powder is stored in sealed polyethene-lined buckets to protect it from moisture and contamination.

Benefits of reusing MJF powder in SLS

1. Cost efficiency

Virgin PA12 powder for SLS or MJF is costly. By repurposing leftover MJF powder that would otherwise be discarded, companies can save significantly on material costs. Even factoring in the additive and energy for mixing, the overall cost per kg drops considerably.

2. Waste reduction

The additive manufacturing sector often faces criticism over material waste. MJF printing typically produces 60-80% unused powder per build. Reclaiming this material for SLS applications allows companies to move toward a zero-waste workflow — critical for meeting environmental goals and sustainability certifications.

3. Cross-technology synergy

Repurposing materials between MJF and SLS shows how different technologies can complement rather than compete. This interoperability is especially valuable in environments that operate both MJF and SLS printers — allowing for more flexible resource allocation and better ROI from materials.

4. Reliable performance on Lisa X

The Lisa X’s robust open-material system and precise control parameters make it highly compatible with custom or reused powders. With proper mixing and storage, prints made using reprocessed HP PA12 demonstrate excellent mechanical strength, dimensional accuracy, and surface finish — comparable to prints made with fresh SLS powder.

5. Environmental responsibility

Adopting reuse protocols like this one reflects well on a company’s corporate social responsibility (CSR) posture. Customers, investors, and regulators increasingly expect manufacturers to optimize resource use. Promoting internal reuse processes sends a strong sustainability signal.

Tips for best results

• Monitor powder aging: even with additives, reused powder won’t last forever. Track the number of cycles and printing performance over time.
• Control humidity: store powder in a dry environment below 20% relative humidity, ideally with silica desiccants.
• Perform print tests: before switching to full production runs, print small calibration parts to verify behaviour.
• Keep batches consistent: mixing multiple sources of used powder may introduce unpredictable results; use single-source batches where possible.

Final thoughts

The Lisa X offers a rare combination of power, flexibility, and openness that unlocks the potential of used MJF powder. Through a carefully structured mixing and preparation process, materials that once had a single-use lifecycle can now be part of a more circular, efficient 3D printing workflow.

As additive manufacturing evolves, material reuse strategies like this one will play a central role in shaping a more cost-effective and environmentally responsible future. If your company operates both MJF and SLS printers, don’t let your used PA12 go to waste—give it new life in the Lisa X.

FAQ: reusing MJF PA12 Powder in SLS Printing with Lisa X

Learn more about calculating the cost of conditioning used MJF powder for SLS printing on Lisa X.

Jakub Malec

Application Engineer

[email protected]

Application Engineer with six years of experience working with SLS 3D printing. He specializes in helping businesses discover how SLS 3D printing can empower their productivity and optimize costs.