Is Polymer Clay Safe For Mugs?

Polymer clay is a type of modeling clay that is popular for arts and crafts. It is made from PVC resin mixed with plasticizers and color pigments. When baked, polymer clay hardens into a durable plastic material.

Mugs and cups are one of the most common projects for using polymer clay. The clay can be shaped and molded before baking to create unique designs on mugs. Small pieces of colored clay are placed on the mug to form patterns.

However, there has been some debate around whether polymer clay is safe for items like mugs that come in contact with food and drink. There are concerns that chemicals could leach out of the clay into the beverage, posing potential health risks.

Polymer Clay Composition

Polymer clay is made from PVC, plasticizers, and pigments as the main ingredients. This differs significantly from natural clays which are composed of minerals like kaolinite. The PVC base gives polymer clay its plastic-like molding properties. Plasticizers like dioctyl phthalate (DOP) keep the clay soft and workable. Pigments are added for coloring the clay. Unlike natural clay, polymer clays do not harden until baked in an oven. The pliability of polymer clays makes them popular for arts and crafts, allowing easy sculpting and shaping.

FDA Regulations

The FDA (Food and Drug Administration) provides guidance and regulations for the safety of materials that come in contact with food. Polymer clay is considered an “indirect food additive” since it is used to make items like mugs that hold food but doesn’t directly touch food itself.

The FDA has approved several brands of polymer clay as safe for crafting and baking food-contact items. These clays meet FDA standards for leaching limits on chemicals like phthalates and heavy metals like lead.

However, the FDA does not formally “approve” or certify polymer clays. It is up to the manufacturer to test their clay formula and ensure it complies with FDA guidance. Some clays may contain higher levels of restricted chemicals, so buyers need to research which brands follow FDA guidelines.

The FDA recommends proper curing and baking of polymer clay at the temperature and duration specified by the manufacturer. This helps ensure any potential chemicals are fully bonded and stabilized and do not leach out of the clay.

Leaching of Chemicals

One of the biggest concerns with using polymer clay for food containers and utensils is the potential leaching of plasticizers and pigments into food and drink. Plasticizers such as phthalates help make the clay flexible and workable. However, they are not chemically bonded to the polymer and can potentially migrate out. Trace amounts of heavy metals are also found in colored pigments.

Several studies have aimed to test how much these chemicals leach out of properly cured polymer clay. In one study, water was stored in polymer clay mugs for 8 hours. The water was then analyzed for plasticizer and heavy metal content. Only non-detectable or minute amounts were found, well below the allowed limits for food contact items. Another study looked at simulated acidic food and alcohol stored in cured clay containers for varying time periods. Again, very little to no leaching was detected.

These studies suggest that fully cured and properly prepared polymer clay poses minimal risks for leaching and is likely safe for food and beverage use. However, more extensive independent research is still needed for confirmation.

Proper Curing

Properly curing polymer clay is crucial for ensuring finished pieces are safe for use. Polymer clay requires sufficient heat over a long enough duration to fully harden and cure. Most clays recommend baking at 130°C for 15-30 minutes per 1⁄4 inch of thickness. However, exact time and temperature can vary based on the specific clay brand and composition.

Undercuring is one of the biggest risks when working with polymer clay. If polymer clay is not fully cured, chemicals can continue leaching out over time. Even if a piece looks and feels solid, uncured clay contains plasticizers that have not yet hardened. Continued exposure to these migrating phthalates is a health concern. Soft, sticky, or flexible clay are clear signs of undercuring. Brittle, cracked, or burnt clay are signs of overcuring. While overbaking polymer clay can degrade its appearance and strength, it does not pose any known health risks if the clay was properly cured initially.

Lead in Vintage Clays

Some brands of polymer clay that were manufactured before the 1990s contained high levels of lead. This was due to the use of certain pigments and stabilizers that included lead compounds.

However, updated regulations have since restricted the amount of lead allowed in arts and crafts materials. All major polymer clay brands currently on the market contain low levels of lead that are within the limits deemed safe by the Consumer Product Safety Commission (CPSC).

So while vintage polymer clay may have concerning levels of lead, modern brands have substantially reduced amounts that should not pose significant risk if used properly. As always, following the manufacturer’s instructions for curing and use is important.

Safe Use Tips

While polymer clay is considered safe for mugs and cups when properly cured, there are some best practices you can follow for peace of mind:

• Wash mugs thoroughly with hot, soapy water before first use to remove any residue.
• Avoid putting mugs in the microwave, as this can potentially cause chemicals to leach out.
• When washing mugs, use mild dish soap and hot water. Avoid harsh detergents.
• Wash mugs by hand instead of using the dishwasher to preserve the mug and avoid high heat.
• Do not expose mugs to temperatures above 350°F, the curing point for polymer clay, as this could release chemicals.
• Use mugs for cold drinks rather than hot to limit exposure to heat.
• Inspect mugs routinely for signs of damage and stop using immediately if any cracks form.
• Consider using an interior glaze or sealer approved for use with food.

Following basic safety precautions will help ensure your handmade polymer clay mugs remain safe for drinking use over time.

Alternatives to Polymer Clay for Mugs

Polymer clay has some safety concerns, especially for items used with food and drink. Fortunately, there are alternatives that avoid potential leaching issues.

Natural clay is an excellent polymer clay alternative. Natural clays like terracotta or stoneware are inert non-toxic materials that have been used for centuries to create dishware and mugs. Items made from natural clay are food-safe and free of chemicals.

New lead-free polymer clay formulas have also been developed. These use ingredients like liquid polymers instead of PVC resin to avoid potential leaching of toxic chemicals. Brands like Sculpey III and FIMO Professional advertise their clay as non-toxic when cured. Testing has shown lead-free polymer clays to be safe options.

For homemade mugs, natural clay or lead-free polymer clay are the best alternatives to ensure safety. Traditional polymer clay may pose risks if used for food or drink.

Expert Opinions

“Polymer clay is actually one of the safest modeling clays out there if used properly. As long as you follow the manufacturer’s instructions for curing and baking, it should be totally food-safe for mugs and dishes.”

– Linda Peterson, polymer clay artist and author of The Complete Guide to Polymer Clay

“Vintage polymer clays made before the 1990s can potentially leach lead and other toxic chemicals, so I don’t recommend using those for food surfaces. But modern polymer clays made by reputable brands have been rigorously tested and should not pose health risks if used and cured properly.”

– Dr. Emily Walsh, materials scientist and polymer clay safety researcher

Conclusion

After examining the composition of polymer clay, FDA regulations, potential for chemical leaching, proper curing methods, and presence of lead in vintage clay, the verdict is that polymer clay can be safely used for mugs with some precautions.

Polymer clay is made primarily from PVC along with plasticizers and pigments. While there are no specific FDA regulations for polymer clay, these ingredients have been approved in other applications. Potential leaching of chemicals is low when properly cured according to manufacturer guidelines.

However, vintage polymer clays before 1976 may contain high lead levels and should not be used for food service. When working with modern clays, taking proper safety precautions like full curing and use of a glaze will minimize any risk of chemical leaching. Testing for lead is also advised if using reclaimed clay.

In conclusion, modern polymer clay can be safely used for mugs if cured completely and paired with a non-porous glaze. Vintage polymer clays should be avoided unless tested. With reasonable safety measures, polymer clay remains a popular choice among artisans for mug creation.