At some point in childhood, most of us get our hands on a lump of soft, malleable clay. We poke holes in its wet and sticky interior. We knead it flat and tear it into pieces only to roll it back together again. We shape it into wonky structures and marvel as they grow brittle and hard in the kiln.
There’s something magic about sculpting with clay and, for some people, it’s a creative passion that lasts a lifetime. Today, we’re going to look at some benefits of working with clay and, in particular, air dry clay which behaves differently to the ceramic clays typically used for creating pottery.
So how do you keep air dry clay from cracking? In short, knead the clay very carefully and for at least 3 minutes before using it. The clay should be approximately a quarter-inch thick for drying. This is the perfect thickness for drying clay without it cracking. Adding small amounts of water during moulding will also help to avoid cracks later on. Try to shape your sculpture in one piece without joints and let the clay dry from all sites. So turn your sculpture while it is drying a couple of times.
We’ll explain why air dry clay is different, what artists use it for and how to manage the moulding process correctly to prevent crumbling.
What Is Air Dry Clay?
The main difference between ceramic clay and air dry clay is that the latter doesn’t require heat treatment. To harden a ceramic pot, you need a special type of oven called a kiln. Not only are these ovens very expensive, but they’re also rarely suitable for regular kitchens and can be challenging to install even in a workshop.
In other words, they’re not suitable for the casual clay sculptor who uses this hobby for relaxation or distraction. Air-dry clay, on the other hand, does exactly what you’d expect. It dries upon contact with air but slowly enough to be molded as it sets.
As no kiln is required, anybody with a passion for clay can start creating.
What Is the Best Way to Sculpt with Air Dry Clay and Avoid Cracks?
Air-dry clay has many benefits, but it also has limitations. Though it dries slowly enough to enable moulding, it begins reacting to air immediately. It means the very slow drying and hardening process actually begins as soon as the clay leaves its packet. As you knead and shape, it is inevitably losing water and becoming stiffer.
The good news is there are steps you can take to remedy this. Here’s some advice on sculpting with air dry clay and preventing crumbling.
- Use a Wax Lined Surface
Air-dry clay is extremely sticky. If you get it on your work surfaces, you may have trouble getting it back off again.
So, we strongly recommend you line surfaces with wax paper or, alternatively, silicone or vinyl placemats. It’ll also minimize the amount of stress you need to put on the clay because you won’t be yanking it off the counter.
- Give It a Squish
Once you’ve taken the clay out of its packet and before you start shaping, spend several minutes kneading it with your knuckles. This process is known as ‘conditioning’ and it’s an easy way to get your material soft and ready for rolling.
Firm kneading loosens up all the platelets in the clay and helps them assimilate.
- Don’t Roll Too Thin
The general rule of thumb for air dry clay is around a quarter inch. This is the optimum thickness for speedy drying with minimal cracking. Sculpting with this material, though low maintenance in some respects, requires a little more care in others.
The key to success is striking the right balance between durability and efficiency.
The thinner the material, the faster it will dry and harden. The faster the clay hardens, the greater the number of cracks. So, it’s really important to find that middle ground at approximately a quarter-inch thickness.
- Add Just Enough Water
The same rule applies to water. Adding small amounts of water during molding is strongly recommended. The clay will crack and warp as you attempt to shape it because it is soft and pliable, to begin with.
As with ceramic clay, it’s good practice to smooth over imperfections as and when you see them develop. This is easy to do with unhardened clay. Simply dip a fingertip into lukewarm water and rub gently until the crack disappears.
There’s a catch though; add too much water and you can easily oversaturate the clay. This makes it sticky and difficult to manipulate.
It will also add hours to the drying process and, thus, more opportunities for a finished work to crack. Keep the clay moist but not very wet. Remember, you can always add water, but you cannot take it away.
- Create Strong Joints
Seams and joints are the most vulnerable areas of a clay structure which is why single piece shapes are always strongest. As most clay creations include multiple bonded pieces, you should know how to create high-quality connections.
First, the two surfaces destined to be joined together must be reasonably dry.
You’re going to be adding a wet glue like substance called ‘slip’ to create the join so avoid adding extra moisture. Using a toothpick, score a crosshatch pattern on the connecting surfaces.
This will increase the strength of the seam by enabling sections of the clay to interlock rather than just press together.
Slip is a rudimentary ‘glue’ used to stick pieces of clay together. It is made by soaking clay scraps in water until they soften into a slurry. This mixture is stirred and pushed through a wires mesh (or similar device) to remove lumps. It is then added to connecting surfaces (usually with a paintbrush) as an adhesive.
If you need help with this, there are countless guides and slip recipes online.
- Allow It to Dry On All Sides
One common mistake is to put a clay creation to one side after moulding and leave it totally untouched. The most consistent way to dry is on all sides.
In other words, you should try to turn the object a few times. Even a completely spherical clay ball will develop an untouched, slow drying section if not turned. Every surface needs some exposure to the air.
Air-dry clay can take anywhere between 24 and 48 hours to dry completely. It depends on environmental conditions such as indoor temperature, humidity, exposure to sunlight and whether the clay is drying evenly on all sides.
Don’t forget to flip it over and prevent a wet, soggy base. A good place to dry clay is in a warm, clean cupboard or cabinet.
- Store Leftover Clay Correctly
The healthier your clay at the start of the sculpting process, the better your chance of producing a perfect project. Leftover clay must be sealed in an airtight container such as a Tupperware box.
Sandwich and refrigerator bags are fine too provided they are sealable. If there’s very little or no air, the clay will stop drying and remain malleable.
Storing partially completed works is trickier, especially if they are very large pieces. Every sculptor has their own technique, so you may need to experiment a little.
Popular strategies include wrapping clay works with clingfilm to trap moisture inside or lightly misting with a gardening spray bottle. This works best if you go back and continue working within 24 hours.
If you plan to create a very large piece such as a spherical ball much bigger than a fist, consider using bulking techniques. You can achieve the effect by moulding solid sections of clay, but this is often wasteful.
It requires the use of huge volumes of material and risks a long and uneven drying process. Instead, many sculptors choose to create a hollow clay mould around something very lightweight such as tinfoil.
The risk of cracks is significantly lower because a smaller volume of clay is being used.
What Types of Air Dry Clay Are Available?
There are a number of different brands available including Pearl Paperclay, Creative Paperclay, Activa Plus Air Dry Clay and Crayola Model Magic which is perfect for sculpting with children.
It’s also possible to make a very basic homemade ‘clay’ called cold porcelain out of corn starch and white glue. While not technically clay, it shares similar characteristics and can be sculpted into shapes and left to set.
Is Air Dry Clay Stronger Than Ceramic Clay?
The lack of heat treatment means ceramic clays will always be stronger when finished than air-dry clays. Treated ceramics are non-porous and, therefore, water-resistant which makes them extra tough.
However, if afforded plenty of time in optimum conditions to fully set and harden, air-dry clays can also be very durable and long-lasting.
To ensure maximum longevity, air-dry clay creations must be kept away from water and humidity. Adding sealers and paints increases durability and makes up for the fact this particular clay variety is less tolerant of fine details.
While air dry clay is not naturally waterproof, materials can be added after hardening to increase its water resistance. Though we haven’t tried the technique ourselves, some artists apply a coating of half PVA glue to half water. After it’s dry, they add a coat of grey acrylic paint for protection.
Once this is dry, they add two topcoats of the desired shade. The method is reportedly good for creating water-resistant outdoor sculptures. We advise you to practice on a small project first.
Why Should I Work with Air Dry Clay?
Perpetual Work in Progress
Air dry clay can be challenging to work with at first – you’re shaping at the same time the material is drying – but it’s also very rewarding. Not only does it dry without kiln assistance, this lack of heat treatment means it never needs to be ‘finished.’
Even after a project has thoroughly dried, new pieces can still be added. If a crack develops after the clay has set, a filler or concealment piece may be attached.
Mixed Media Opportunities
The lack of heat treatment means it’s safe to add all manner of creative materials to a clay structure of this type. You can’t combine ceramic clay with metal, wood or plastic features because they’ll burn in the kiln.
This is not a problem for air-dry clay. It can be attached to, moulded around, draped over or layered on top of many different materials.
For instance, many sculptors include armatures in their work. This is an internal frame, normally made out of thin wire, which the sculptor moulds their clay around.
The use of armatures increases the variety of effects that can be achieved with clay. If a wireframe is created first, for example, it may be used to hold a clay structure above its base and even create the illusion of motion.
It’s worth mentioning that wire armatures also add strength to sculptures. Imagine you’re creating the figure of a horse out of air-dry clay. To shape a standing horse, most of the clay would need to rest evenly on top of four thin legs.
Moulding the clay around a sturdy wire frame gives these legs (and any other fragile areas) extra durability.
The Final Word On Sculpting with Air Dry Clay
Air-dry clay is a wonderful option for passionate crafters because it can be used by anybody in almost any environment.
While traditional ceramic clay requires a lot of specialist equipment, this variety needs nothing but your hands.
It comes in many different varieties including child-friendly clay. It’s not as hard as ceramic clay – when dried, it has a slightly softer ‘polystyrene like’ texture – but this means it is more prone to dents than chips and smashes.
It’s one of our favorite materials to work with and we hope you have a great time with it too.