In this article, you are going to learn all the details of how to make the ultra light clay, sharing the process, machine, formulation. Subjects include,
- Introduction of ultra light clay
- Preparation of PVA Glue
- Preparation of Boric Acid and Borax Solution
- Preparation of Semi-Gel for Expansion
- Expansion by Extrusion Machine
- Final Mixing of the clay
- Guidelines to modify formulations
Introduction of ultra light clay
Ultra light clay, also known as air-dry clay or lightweight clay, is a type of modeling material that is soft, pliable, and easy to work with. It’s called “ultra-light” because it’s significantly lighter than traditional clay. Here are some key features and uses:
1. Lightweight: Unlike traditional clay, which can be heavy and dense, ultra light clay is lightweight, making it ideal for creating delicate and intricate designs.
2. Air-dry: One of the main advantages of ultra-light clay is that it air-dries, meaning it doesn’t require baking in a kiln or firing in an oven like traditional clay. This makes it convenient for crafting at home without the need for special equipment.
3. Soft and pliable: Ultra light clay has a soft, pliable texture that makes it easy to mold and shape. It’s great for both beginners and experienced artists alike.
4. Color options: It’s available in a wide range of colors, including primary colors as well as metallic and pastel shades. This variety allows for endless creativity in crafting projects.
5. Versatile: Ultra light clay can be used for various crafting projects, including sculpting figurines, making jewelry, creating decorations, and even for educational purposes in schools and art classes.
6. Non-toxic: Most brands of ultra-light clay are non-toxic, making them safe for use by children under adult supervision.
7. Finishing: Once dry, ultra light clay can be painted, varnished, or embellished further to add detail and enhance the finished piece.
Preparation of PVA Glue
| Items | Weight,kg | Content,% |
| PVA 2488/BP24 | 10 | 12.5% |
| Deionized water | 70 | 87.5% |
| Total | 80 | 100% |
- Mix PVA and water in the mixer at temperature 50-80C till PVA granule all solved.
- PVA, better to choose middle molecular weight. Too high, the clay will be hard. Too low, the clay will be soft;
- The higher proportion of PVA, the better qulity of clay, but at the same time, the cost will be higher;
- You have to use the deionized/pure water, neutral PH and less impurity, or will influence the cross-linking.
Mixer with Heating
Preparation of Semi-Gel for Expansion
| Items | Weight,kg | Proportion,% |
| PVA glue | 400.00 | 84.71% |
| Waytop Microspheres 140MW | 50.00 | 10.59% |
| Boric Acid | 3.40 | 0.72% |
| Borax | 0.80 | 10.00% |
| Hot Water | 18.00 | 3.81% |
| Total | 472.20 | 100.00% |
Processing Step:
- Firstly, use the hot water to dissolve the borax and boric acid;
- Secondly, add PVA gule+microspheres into the mixer and mix evenly;
- Gradually pour the borax and boric acid solution into the mixture and mix evenly till the mixture is not sticky to hand.
Expansion of Ultra Light Clay by Extrusion Machine
- 3 heating zone, the heating temperature usually set from 100C-140C, from low to high temp. For example, 1st zone 100C, 2nd zone 120C, 3rd zone 140C. The temperature setting is also influenced by the speed of the screw, the faster of the screw, the higher of temperature.
- Don’t need the nozzle as it will restrict the expansion of the gel;
- Other specifications, follow the normal extrusion machine.
Expansion Extrusion Machine
Final Mixing of Ultra Light Clay – Equipment
Since the viscosity of the final modeling clay products is very high, we would recommend a slow type of mixing/kneading equipment, e.g. planetary or double arm mixer, kneader.
Final Mixing of Ultra Light Clay- Formulation
| Items | Weight,kg | Proportion,% |
| PVA gule | 72.00 | 63.91% |
| Gel expanded | 32.00 | 28.41% |
| Preservative | 0.30 | 0.27% |
| Fungicide | 0.30 | 0.27% |
| Pigment | 0.30 | 0.27% |
| Glycerol | 1.50 | 1.33% |
| CMC | 0.30 | 0.27% |
| HPMC | 0.00 | 0.00% |
| Sorbito | 0.00 | 0.00% |
| Vaseline | 0.00 | 0.00% |
| Boric acid | 0.85 | 0.75% |
| Borax | 0.10 | 0.09% |
| Hot water | 5.00 | 4.44% |
| Total | 112.65 | 100.00% |
- Firstly, use the hot water to dissolve the borax and boric acid;
- After all other items mixed, gradually pour the borax and boric acid solution into the mixture and mix evenly till the mixture is not sticky to hand.
Guidelines to modify formulation
The clay is sticky
• Increase dosage of cross-linker
• Increase dosage of binder(s)
• Reduce water content
Poor elasticity of the clay when wet
• Increase dosage of cross-linker
• Increase dosage of both binder and crosslinker
• Change to a PVA with higher molecular weight
Poor moldability
• Decrease dosage of cross-linker
• Decrease dosage of binder
• Increase water content
• Decrease dosage of Microspheres
Poor bounceability
• Use PVA with lower molecular weight
• Increase dosage of cross-linker
Dried clay is too brittle
• Increase dosage of vinyl acetate
• Increase dosage of glycerol
For more applications, please check our application sections:
https://www.expandablemicrosphere.com/applications
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