Polymer clay and modeling clay are both popular materials used in arts and crafts. They’re both fun to work with, simple to shape, and can produce great results. However, there are definitely some key differences that can make one option more preferable to the other.
What’s the difference between modeling clay and polymer clay? Modeling clay is available in in bake-to-harden, air-dry, and no-dry options, and the no-dry options can be used over and over again. Polymer clay is a type of modeling clay formulated so that it can be oven-baked to harden, which makes it more permanent and durable.
If you are curious about how this works and how to tell the difference between these two types of products, this blog post will help you decide which type is best for your next project.
What Is Modeling Clay?
Modeling clay behaves just like the clay that pottery artists often used to make pottery and ceramics. It is moldable into different shapes and forms using simple shaping tools.
There are actually a few different types of modeling clay, including non-dry oil-based modeling clay, air dry clay, and even polymer clay.
Oil-Based Modeling Clay
Modeling clays made from various types of oils and minerals are known as oil-based clays.
Thanks to the oil content, they retain their malleable properties even when left in dry environments for a long time – the oils do not evaporate when exposed to air.
Because of this characteristic, oil-based modeling clay can be used over and over again, which is why it’s a very popular material for clay animations (claymation).
However, because of the oil content, oil-based modeling clay cannot be baked to harden. If you try to bake oil-based modeling clay, the clay will easily crumble.
Air-Dry Modeling Clay
Air-dry clay is defined by its most prominent characteristic: it can harden at room temperature (hence the name’ air dry’ clay). Unlike polymer clays, which have to be heated in an oven to cure, air-dry clay can harden on its own.
The exact time that it takes to harden air-dry clay is dependent on the temperature, the thickness of the clay, and even the brand of the product that you’re using. Most types of air-dry clay will take two days to a week to cure completely.
However, even when air-dry clay has completely cured, it’s still not very durable compared to other types of clay. It is not waterproof and cannot be used to handle food or drinks, so its applications are quite limited.
Here’s a great tutorial for sculpting with air dry clay for beginners from Sofia Bue on YouTube.
Polymer Clay
Yes, polymer clay is a type of modeling clay. However, compared to other types of modeling clay, polymer clay is designed so that it can be oven-baked to harden.
Depending on the polymer clay product that you have, it only takes 15 minutes in the oven at around 275°F to turn polymer clay into ‘pottery.’ After polymer clay hardens, you can paint or even glaze it any way that you like.
Why is that the case? Let’s take a closer look at polymer clay in the next section.
What Is Polymer Clay?
Polymer clay is considered modeling clay, but it is made from polymer polyvinyl chloride (PVC) instead of clay minerals.
Unlike mineral clay, which is used in traditional pottery, this type of modeling clay does not contain any minerals. Instead, it is formulated to behave like traditional clay, which can easily be shaped and will harden under high heat.
However, mineral clay typically requires extremely high heat (2124℉ – 2264℉) to harden, which makes it quite difficult for casual hobbyists, as this temperature can only be achieved in an industrial kiln.
In this aspect, polymer clay is preferable to mineral clay, as it can harden when oven-baked for just a few minutes in moderate heat (around 275°F). This is why polymer clay is super popular for arts and crafts.
Polymer clay is also preferable to air-dry modeling clay because it won’t dry out until it is baked in the oven, which gives you more time to shape and manipulate the clay without the risk of it crumbling as it dries.
After it’s completely cured in the oven, it’s also more durable than air-dry clay. Although it’s definitely not as waterproof or durable as traditional kiln-fired pottery, oven-baked polymer clay can maintain its structure and shape relatively well after it’s fired.
Here’s an awesome tutorial for using polymer clay from Sofia Blue on YouTube.
How To Harden Modeling Clay
Because there are a few different types of modeling clay, how to harden modeling clay depends on which type of modeling clay you are using. Let’s take a look at how to harden each type of modeling clay below.
Oil-Based Modeling Clay
Modeling clay that has an oil-based formula is made by mixing natural clay minerals with wax and non-drying oils.
It is typically worked and reused without ever drying out, and it’s more suitable for those who enjoy the process of sculpting rather than finishing a product. Oil-based modeling clay is what filmmakers use to make claymation films.
Unfortunately, there’s no way to harden oil-based modeling clay. If you want to harden the clay and preserve your creations, you will need to opt for a different type of clay.
Air-Dry Clay
Air-dry modeling clay has a water-based formula that will harden when the water content evaporates completely. This process typically takes anywhere from 24 hours to a week, depending on the brand that you’re using.
Because air-dry clay will dry out without the assistance of heat, there’s a risk of the clay drying out while you work. You can add a little bit of water to reactivate the clay, but make sure not to add too much water, or the clay will crack and crumble when it’s dry.
Fortunately, there’s nothing you really have to do to harden air-dry clay. Just leave it out in a cool and dry area of your home, and let the natural drying process happen! However, it will not be waterproof once dry.
Can You Bake Modeling Clay?
The only type of modeling clay that you can bake is polymer clay. Although polymer clay will dry out if you leave it alone for a few days, it’s not considered completely cured until you bake it in the oven.
Since there are a few brands that sell polymer clay, you will need to follow the instructions closely to achieve the best result when baking polymer clay.
Typically, it only takes about 15 minutes in the oven at 275°F for the polymer clay to harden. However, depending on how thick or solid your creation is, it may take more or less time for the polymer clay to harden completely.
After baking the polymer clay, you should leave it to cool down for a few minutes before painting it. Hardened polymer clay works well with almost every type of paint, but we suggest using water-based paint (like acrylic) so that you can easily fix any spills or mistakes if needed.
Polymer Clay Vs. Modeling Clay
Now that you know what modeling clay and polymer clay are, let’s take a look at the difference between the two and which one will suit your next project.
Material
Modeling clay either have an oil-based (non-drying) or water-based (air-dry) formula, but the essence is still traditional clay minerals, which makes the material flexible and easy to work with.
In comparison, polymer clay is made from PVC, which is essentially plastic and doesn’t contain any clay minerals at all.
However, because polymer clay is made from a synthetic material, it’s also available in a wider range of colors, including basic colors, translucent colors, and even glitter options. This makes it preferable for arts and crafts.
Drying
We’ve mentioned how to dry modeling clay. If you have an oil-based modeling clay, then there’s essentially no way to dry it to make a completed creation. If you have a water-based modeling clay, then it can air-dry after 24 hours to a week.
In comparison, polymer clay can harden when it’s baked in an oven for about 15 minutes. However, if you leave polymer clay alone for too long, it can dry out and become brittle and unworkable.
Uses
Both non-drying and air-dry modeling clay are reusable, so it’s often used in animation or projects that require flexibility. It’s also quite useful if you’re a sculptor looking to experiment with new ideas without having to waste materials.
Polymer clay is beloved by arts and crafters to make beads, jewelry, as well as figurines, and models. It’s simple enough to use but still allows for a lot of creativity and experimentation.
Durability
As we’ve mentioned, modeling clay is not very durable, even the air-dry type. It can easily crumble if it doesn’t dry correctly, and even when it is, it is not waterproof and still not very durable.
In comparison, polymer clay is more durable. After it is baked in the oven, it is relatively water-resistant (even though it’s not waterproof enough to handle water and drinks). It’s also quite durable, so it’s suitable for making beads and jewelry.
However, make sure that polymer clay is stored in an air-tight container because if it’s dried out, it will crumble, and you won’t be able to work with it again.
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