Baking Polymer Clay in Cornstarch or Baking Soda

You’ve got your polymer clay creation finally perfected. You smoothed out the edges and got that swirl to sit just right. It’s finally time for the oven. You know that if you place it on a pan, you’ll have a smooth, shiny spot where it was resting, and you’re also worried that it will roll around as it cooks, ruining all your hard work. Plus, part of it is light-colored, so you don’t want it to brown in the oven like a dinner roll. What can you do?

Cornstarch and baking soda are many clayers’ go-to solutions when it comes to baking their creations. Both offer answers to many of the problems that occur in the oven, like rolling, uneven spots and burning. Each one has considerations to keep in mind for your finished piece.

Baking Polymer Clay in Cornstarch

Cornstarch is an excellent solution to common problems with baking polymer clay pieces:

  • It keeps the clay from burning. Many ovens that use an electric element do not circulate heat, so unless you’re using a convection oven, this heat pattern can sometimes burn your clay, leaving brown spots even at proper temperatures. Covering your clay in cornstarch or baking soda keeps it protected from some of the harshness of the heating element. It may take a little longer as the heat has to travel through the clay, but it is especially worth it for lighter colors that may show their baking more easily.
  • It helps the clay maintain its shape. Sculptures won’t sag, beads will stay round and you can say goodbye to flat, shiny spots. Just bury them partially in the cornstarch, and they keep their shape. It’s a great way to keep your finishes consistent.
  • It prevents the clay from rolling. The bed of cornstarch keeps pieces separate and fixed in place, so they don’t roll to one corner and cure together in the oven. It also prevents them from tipping on their sides, possibly deforming your project.

Another benefit of cornstarch is its smoothing properties. Often, clayers will dip their fingers in cornstarch and run them over the surface of their raw polymer clay to smooth it out. This action helps to remove those pesky fingerprints. When using cornstarch to smooth a surface, be sure to avoid scrubbing it in, which can embed the cornstarch in the clay.

Cornstarch does have a few features you’ll need to be aware of. They include:

  • Leaching the clay. Polymer clay has plasticizers in it that help it remain flexible even after it is baked, but absorbent materials can pull these substances out of the clay. If you leave cornstarch on for too long, it will leach from the clay, pulling out its plasticizers and coloring. This leaching can make your piece more brittle and cause discoloration. It may break or crack more easily. To prevent this effect, place your clay in the oven immediately after putting it in the bed of cornstarch. Do not leave it in the cornstarch for very long.
  • Cleaning. The softer your clay, the more cornstarch will stick to it. Moisture in the clay can cause it to clump and pull the color out. Remember that cornstarch does not dissolve in water, so if you’re trying to clean it after baking, you might need a little more than just a rinse. Brushing it off with a toothbrush should get all those particles out. You may still find a few specks of discoloration, but you can address that with some light sanding.

Baking Polymer Clay in Baking Soda

Baking soda performs a similar function as cornstarch, working to prevent burning, keep the clay’s shape and prevent rolling.

Like cornstarch, baking soda can also leach clay. The powder can remove plasticizers from the clay if you leave them in contact for too long, so be sure to bake the clay right away if you put it in baking soda.

Baking soda will also stick to your piece like cornstarch. However, it does so a little differently. Baking soda dissolves in water and is much easier to remove, so you don’t need to scrub at it. It also offers less discoloration than cornstarch and won’t leave any residue. A quick rinse is usually enough to get rid of baking soda. As nice as that easy clean-up sounds, though, baking soda isn’t without its difficulties.

The primary challenge of working with baking soda is that it has larger particles than cornstarch, and they can make deeper marks in your clay. Divots and discolorations are more common than they are in cornstarch-baked pieces. These marks often require a little more sanding to get them to go away, so baking soda may not be ideal for detailed pieces with intricate designs where sanding is not an option.

Should I Use Baking Soda or Cornstarch?

Both being similar substances, baking soda and cornstarch can aid in your polymer clay-baking tasks. Either one can:

  • Keep your clay from burning, which prevents discoloration and cracking.
  • Ensure your pieces stay the correct shape, which keeps sagging, flatness and smushed designs at bay.
  • Make sure your pieces stay in place, so they don’t meet up and connect together during baking.

Selecting one of the powders depends on your project and your preferences. Cornstarch can be harder to remove after baking and may take some elbow grease in the form of scrubbing it down with water. Baking soda is easier to remove but is made up of larger particles which can leave marks in your piece and require more sanding to remove.

If you are working with a piece with intricate details, sanding might not be an option, so cornstarch would help you avoid that. You could also use cornstarch if you just don’t like sanding. If your piece is thicker and you have areas to sand but don’t want to fight with scrubbing it, you can use baking soda.

Again, personal preference is a significant factor in which approach is “best.”

Effective Polymer Clay Baking Solutions

Overall, baking soda and cornstarch are excellent solutions to some of the most frustrating problems with baking polymer clay pieces. They are cheap and easy to find — although in some places outside of the United States and Canada, you may need to look for cornflour instead of cornstarch. They can help you achieve the smooth texture and beautiful color of a well-baked polymer clay project.

For clay that fuels creativity, check out our line of Sculpey III polymer clays. With superior color palettes and the strength and flexibility of Sculpey III, you can make your most innovative creations come to life.

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