Category: 3D Printing

What Does Food Safe Really Mean?

To begin, it’s important to clarify a few key terms:

• Food grade means that the material is either safe for human consumption or permitted to come in contact with food.
• Food safe means that a food-grade material meets the requirements determined by the intended use and will not create a food-safety hazard.
• Food contact surfaces include any surface that may come into direct contact with food. These surfaces must be made of non-toxic materials and designed to withstand the environment of their intended use, including exposure to cleaning compounds, sanitizing agents, and cleaning procedures.

Food grading and food safety concern a specific way to ingest parts, called migration. Particles as small as a few nanometers and up to several hundred nanometers may get transferred each time various materials encounter with each other, for example from components of the 3D printer to the 3D printed object, and from the object to the food.

Because migration levels are very low on occasional contact, food grading typically concerns items that are in prolonged contact with food such as containers, straws, utensils, plates, and food molds. Different testing institutions will adhere to different government-imposed risk tolerances and approved substances, which for the US is described by the FDA CFR 21 and for the EU in guidelines 10/2011.

To be considered food safe according to the FDA Food Code, a material has to meet the following requirements:

• No migration of deleterious substances
• Does not impart colors, odors, or tastes
• Safe under normal use conditions
• Durable, corrosion-resistant, and nonabsorbent
• Sufficient in weight to withstand repeated washing
• Finished to have a smooth, easily cleanable surface without breaks and sharp internal angles
• Resistant to pitting, chipping, crazing, scratching, scoring, distortion, and decomposition
• Accessible to inspection

Any FDA or EU approved material includes not only the raw polymer but also the additives or masterbatch. These might contain components such as plasticizers, impact and heat distortion modifiers, UV-stabilizers, flame retardants, anti-fouling, anti-static, anti-slip, foaming and clarifying agents, anti-oxidants, aromatic nucleators, carbon alloys, phosphorescents, fillers, thickeners, chain extenders, metal deactivators, dyes, and a carrier resin.

General Food Safe 3D Printing Considerations

Bacteria Buildup

A 3D printed part can turn into a petri dish squirming with bacteria within weeks. Even though some materials will survive the dishwasher, so will dangerous bacteria such as E. coli and salmonella that live in the little nooks and crannies. Some toxic molds find favorable growth conditions on several types of plastic and are hard to remove. Neither cleaning with bleach nor microwaving your polymers is an option for eliminating germs. 

While bacteria buildup might not be an issue for disposable items, if you’re planning to create a part for long-term use, using a food-safe coating is highly recommended.

Food Safe Coatings and Sealants

The best option to reduce the risk of particle migration and bacteria buildup is by dip coating the 3D printed parts with a food grade epoxy or polyurethane resin, such as Masterbond’s EP42HT-2FG or ArtResin or an FDA approved PTFE (known as Teflon®) to seal their surface.

However, note that coating also doesn’t guarantee food safety for prolonged use as not all of these coatings are dishwasher safe, and they may degrade over time, exposing the original, potentially non-safe surface.

Dishwasher Safety

Most 3D printing materials have a low heat deflection temperature (HDT), which means that the 3D printed parts might become brittle and crack, or deform and warp at elevated temperatures. If you’re planning to clean a 3D printed part in a dishwasher, make sure to double check that the material is dishwasher safe and if there are any specific recommendations for washing temperature.

Food Safe Equipment

As particles might migrate from components of a 3D printer to 3D printed parts, it is crucial that any components that might come in contact with the 3D printing material or the part are food grade and do not contain or leach harmful chemicals. 

This includes taking precautions when using multiple materials, as some materials previously used in the 3D printer might have contained toxic particles and made contact with some components.

Food Safe 3D Printing Materials

Many 3D printing materials are not food safe and might contain toxic chemicals. Only use materials to 3D print parts intended for food contact that are certified for food safety.

Food Contact Time

As may be expected, the risk of migration is higher if the food is exposed to the 3D printed part for an extended time period. In general, try to limit food contact time and take further precautions for parts that will be in contact with food for longer periods of time.

Using 3D Printing to Create Food-Contact Items

Think about the reason why you’d like to use 3D printing for a food-contact item. If it’s to create custom shapes and forms, in most cases, there are indirect ways to use 3D printing to create these custom parts, for example with molding. See an example in the next section.

Food Safe 3D Printing With Stereolithography (SLA)

SLA 3D printing uses a laser to cure liquid resin into hardened plastic in a process called photopolymerization, resulting in parts that have the highest resolution and accuracy, the clearest details, and the smoothest surface finish of all plastic 3D printing technologies.

Is resin food safe? The answer is no. Substances may migrate from SLA parts which makes none of the resins and printed parts food safe by default. While some resins for dental and medical applications are certified biocompatible, that doesn’t mean that they’re food safe. These materials are certified for specific applications and should not be used for food contact products.

SLA parts have a smooth surface finish that makes it easier to use coatings to seal their surface and prevent the buildup of bacteria. The factors which affect the ultimate smoothness of a part include resin type, layer thickness, build orientation, mesh triangulation resolution of the 3D model, and the curing profile of the SLA resin. Printed parts require washing and post-curing according to the manufacturer’s instructions before the coating is applied. However, note that coatings don’t guarantee food safety, as the coating may interact with the resin or degrade over time, exposing the original, potentially non-safe surface.

Molds

Creating custom molds is a common way to leverage the benefits of SLA 3D printing to produce highly detailed custom parts without having the 3D printing parts come into direct contact with food. While SLA 3D prints aren’t suitable for directly molding foods, SLA 3D printers are perfect tools to create mold negatives, which can be vacuum formed using food safe plastic.

Electroplating

Electroplating is the process of coating parts with metal using an electric current. The process is most commonly used for decorative purposes or to prevent corrosion by creating a durable surface.

SLA parts are ideal for electroplating due to their smooth surface finish. However, as plastics are nonconductive surfaces, SLA 3D prints have to be rendered conductive by coating with graphite, conductive lacquer, electroless plate, or a vaporized coating.

Food safe metal coatings are available, but as the process involves various chemicals, making sure that the workflow is approved for food contact is the developer’s own liability.

Ceramics

SLA 3D printing offers the unique possibility to produce ceramic parts. After 3D printing, parts can be fired in a kiln to burn out the resin and form a true ceramic part that is strong and heat-resistant. With subsequent food safe glazing, the parts will become more hygienic and resistant to most chemicals.

A variety of food-safe glazes are available on the market, but make sure to follow the manufacturer’s instructions in accordance with food safety guidelines.

Food Safe 3D Printing With Fused Deposition Modeling (FDM)

FDM is a 3D printing process that builds parts by melting and extruding thermoplastic filament, which a print nozzle deposits layer by layer in the build area.

The extruded material is circular in cross-section, which leaves very narrow crevices in between layers with a depth directly proportional to layer height. It is recommended in any case to print at the lowest feasible layer height for food safe parts.

Consequently, the main challenge with FDM parts is avoiding the buildup of bacteria. To be truly food safe in the long term, an FDM 3D print needs to have a smooth surface. Chemical smoothing with solvents like acetone, d-Limonene, or ethyl acetate removes many of the irregularities of the print resulting in a smooth, glossy appearance. However, applying a subsequent food-safe coating is still highly recommended.

Food grade filaments do not contain any composite particles so will not wear down the nozzle into the print. Nevertheless, avoid brass nozzles that contain lead and use a dedicated stainless steel nozzle instead for all food contact items.

Always check the compatibility of your 3D printer’s components with the filament. For example, PEI is a material that is FDA compliant and offers great mechanical benefits but needs to be processed at over 300 °C, which requires a specific printer solution.

Food Safe FDM Materials (Food Safe Filaments)

The most common questions around FDM food safety concern two popular materials. Is PLA food safe? Is ABS food safe? The answer is, it depends.

Food safe 3D printing filaments include PLA, PP, co-polyester, PET, PET-G, HIPS, and nylon-6, as well as some brands of ABS, ASA, and PEI. Having to run parts through the dishwasher rules out PET, nylon, and PLA because these plastics soften and distort around 60–70 °C. For applications involving hot liquids, co-polyester, High Temperature PLA or PEI are most suited.

While not reflected in the regulations, some studies suspect that polystyrene may leach styrenes, co-polyesters might cause health concerns and that food-grade FDM filaments might lose their safe status due to oxidation and thermal degradation from the printing process.

FILAMENT	MNFG BRAND	FDA RECOMMENDATIONS	SMOOTHABLE	DISHWASHER SAFE
ABS	Adwire PRO	Approved	Yes, acetone	Yes
	Innofil3D	Approved except red, orange, and pink	Yes, acetone	Yes
ASA	Innofil3D	NA		Yes
Bendlay	Orbi-Tech	NA	Yes, brake cleaner	No
Biocompound	Extrudr GreenTEC	NA
Co-Polyester	Colorfabb XT	Approved	No	Yes
HIPS	Easyfil	Compliant	Yes, d-limonene	Yes
	Fillamentum	NA	Yes, d-limonene	Yes
	InnoFil3D	Approved	Yes, d-limonene	Yes
Nylon	Taulman Nylon 680	Compliant		No
PEI	ULTEM® 1000	Compliant		Yes
PET	InnoPet EPR	Approved except red and orange	Yes, ethyl acetate	No
	Refil	Approved	Yes, ethyl acetate	No
	Taulman T-Glase	Approved	Yes, ethyl acetate	No
	Verbatim	Compliant	Yes, ethyl acetate	No
PET-G	Extrudr MF	NA	Yes, ethyl acetate	No
	HDGlass	Approved	Yes, ethyl acetate	No
PLA	Filaments.ca TrueFS	Approved	No	No
	Fillamentum	NA	No	No
	Innofil3D	Approved except red, orange, pink, apricot skin, grey, and magenta	No	No
	Copper3D PLActive Antibacterial	Approved	No	No
	Makergeeks	Approved	No	No
	Purement Antibacterial	Approved	No	No
PLA-HT	Makergeeks Raptor	Approved	No	Yes
	Makergeeks Raptor	Approved	No	Yes
PP	Centaur	Compliant	No	Yes
	InnoFil3D	Approved	No	Yes
	Nunus	Compliant	No	Yes
	Verbatim	Compliant	No	Yes
SBS	Filamentarno	NA	Yes, d-limonene	Yes

Food Safe 3D Printing With Selective Laser Sintering (SLS)

Selective Laser Sintering is a 3D printing process that use a high-powered laser to fuse small particles of polymer powder. The most common material for laser sintering is nylon, a popular engineering thermoplastic with excellent mechanical properties.

While some SLS powders are graded food safe, the particles on the surface of printed parts might not fuse completely, resulting in parts that are inherently porous and do not deal well with moisture and mold growth. Even though the nylon 12 powder can be steam cleaned in an autoclave, it is best to coat SLS parts with food-safe coatings to seal their surface.

Conclusion and Further Reading

Food safety with 3D printing is not a simple matter that will boil down to a clear yes or no answer. Producing 3D printed parts for food contact items requires careful consideration of the risks depending on their intended use.

For further information on food safety and 3D printing, we recommend reading the following:

• FDA Regulations CFR 21
• EU Guidelines 10/2011
• Risk Assessment of 3D Printers and 3D Printed Products
• The Tricky Business of Choosing Plastic for Food Contact Applications