How to Make 3D Printed Safe Items for Food

Using your 3D printer to create custom cookie cutters, cake toppers, or maybe even unique 3D printed utensils opens exciting possibilities in the kitchen. But before you start printing your next culinary gadget, ask yourself this question: Is it safe to use these printed items with food? Getting this wrong could pose health risks, so understanding the process for different printing technologies is key.

This article explains how to approach making food safe 3D print objects. We will cover:

·Why 3D prints, especially from FDM printers often aren't safe for food initially.

·Choosing the right materials for FDM, PETG vs food grade PLA.

·Food safety considerations for other technologies like SLA and SLS.

·Important printing steps for improving safety primarily for FDM.

·Why you should use a food safe coating for 3D prints.

·Bringing it all together to make a 3D printed safe item.

Why standard FDM 3D prints can be risky for food

Most accessible 3D printers work by melting plastic filament and depositing it layer by layer – this is called Fused Deposition Modeling (FDM). This process itself creates challenges for food safety:

1.Tiny gaps

Even on prints that look smooth, FDM creates microscopic gaps between the layers. These gaps are perfect hiding places for bacteria from food, and they're extremely hard to clean completely.

2.Material make-up

Common FDM plastics or filaments often contain chemicals or colorants not intended or tested for contact with food. These substances could potentially transfer to your food.

3.Printer contamination

Parts of the FDM printer, like a standard brass nozzle, might contain small amounts of lead. Something else to consider is that, switching between different types of plastic may leave behind residues.

Good 3D printing safety practices are essential when food is involved, regardless of the technology.

Choosing the right material for FDM: PETG and food grade PLA

Selecting the correct filament is the first important step for FDM printing. The most common choices considered for food contact are PETG and specific types of PLA.

PETG (Polyethylene Terephthalate Glycol)

PETG is often recommended for food-related prints for several reasons:

·Strength: It is generally stronger and less brittle than PLA.

·Chemical Resistance: PETG usually shows good petg chemical resistance, holding up well against food acids.

·Printing: 3D printing petg is common, though it might need higher temperatures than PLA.

Look specifically for PETG that the manufacturer states meet food contact standards like FDA compliance. This ensures the plastic itself is appropriate. Many see this certified type as the best petg for these uses. Regarding recycling, is petg recyclable? Often yes, but you can check locally for code #1.

PLA (Polylactic Acid)

PLA is very popular, often sold as 3D filament pla 1.75 mm on a 1kg filament spool. But for food use, you need food grade pla.

·Certification is important: Standard PLA usually has additives that are not food safe. You must use PLA specifically marked and certified as "food grade."

·Heat Issues: PLA softens at lower temperatures than PETG, making it unsuitable for hot items or dishwasher cleaning.

ABS (Acrylonitrile Butadiene Styrene)

ABS is another common FDM filament. While abs print speed can be good, it is generally not considered food safe because it contains styrene, which you don't want near your food. So, it is better to stick with certified PETG or PLA for food applications.

Other technologies like SLA and SLS

While FDM is very common, other 3D printing methods like SLA (Stereolithography) and SLS (Selective Laser Sintering) exist, each with different food safety considerations.

SLA or resin printing

This method uses UV light to cure liquid resins. While SLA produces very smooth surfaces, standard resins are generally toxic and not suitable for food contact, even after curing. They can leach chemicals. While special biocompatible resins exist which are often for dental use, they are expensive, and their food-contact safety isn't guaranteed for all applications. If attempting food contact with an SLA print, using it as a mold for a food-safe material like vacuum forming or applying a thoroughly tested, certified food safe coating for 3D prints is essential, but risks remain if the coating is damaged.

SLS or powder printing

This method uses a laser to combine powdered material which most of the time is nylon. Some SLS powders like certain types of Nylon PA12 can be certified for food contact. However, SLS prints are naturally porous, meaning they have tiny holes that can trap bacteria, similar to FDM layer lines but inherent to the material structure. Therefore, sealing SLS prints with a reliable, certified food safe coating for 3D prints is crucial to make them non-porous and cleanable enough for food use.

In general, while possible with extreme care and specialized materials/processes, achieving food safety with SLA and SLS typically presents higher hurdles (toxicity concerns with resins, inherent porosity with SLS) compared to FDM using certified filaments, which still requires careful handling and often coating.

Printing process tips for better safety (FDM focus)

Just using the right plastic isn't the whole story, especially with FDM. How you print matters:

·Use clean gear

Use a dedicated nozzle made of stainless steel which does not have lead concerns like brass just for your food-safe FDM filaments. Clean the printer's filament path well.

·Tune settings

Use printing temperatures and speeds that help the layers stick together tightly, reducing gaps.

·Design simply

Avoid complicated designs with tiny crevices that are hard to clean.

Following these steps helps make the initial 3D printed safe object when using FDM.

Why a food-safe coating is important (all technologies)

It does not matter if you are using FDM, SLA, or SLS, surface imperfections like layer lines or natural porosity remain a risk for trapping bacteria. Applying a food safe coating for 3D prints is strongly suggested for almost all 3D printed items intended for food contact.

·Seals the surface: A certified food-safe epoxy or resin smooths over imperfections, creating a solid, non-porous surface.

·Makes cleaning easier: The smooth surface is much easier to wash effectively.

·Adds a barrier: It puts an extra safe layer between the printed material which might be certified but still porous, or potentially problematic like resin and the food.

This step is crucial for items you plan to reuse, like 3D printed utensils, making them truly easier to manage for a food safe 3D print.

Making food safe prints is possible with care

Creating 3D printed safe items for food contact can be done across different technologies, but it requires a careful, informed approach.

1.Choose appropriate materials

For FDM, use filament specifically labeled food grade pla or food-contact compliant PETG (check it's 1.75 mm 3D printer filament if needed). For SLA/SLS, understand the significant material limitations like resin toxicity, powder porosity and seek certified materials if available, knowing post-processing is critical.

2.Print carefully especially FDM

Use clean, dedicated parts like a stainless-steel nozzle for FDM and settings that minimize flaws. Maintain a clean printing environment.

3.Seal the print

Apply a food safe coating that is certified for 3D prints to form a non-porous surface that is cleanable. This is vital for SLA/SLS and highly recommended for nearly all FDM food-contact items, especially reusable ones.

Simple, single-use FDM items might pose lower risks, but reusable items or anything printed with SLA/SLS absolutely benefits from careful material choice and a food-safe coating to lower risks effectively.