Q&A for How to Harden a Sand Dollar

Add a little bleach to the water when you wash the sand dollars, or you can set them out in the sun. Use a tiny bit of bleach in soapy water when you clean them to kill any bacteria so they don't smell.

Let them rest where there is sunshine for about a week. They will naturally dry out.

You can just use regular Elmer's glue.

Carefully drill a hole with a 1/16 in. drill bit about 1/4 in away from the edge. Slip your chain or cord in and tie it. In some cases the sand dollar will have holes already in it and you can use that instead of drilling a hole. But make sure to harden them.

Yes. The sand dollar should be hardened on all sides. It is recommended to do the edges as well.

You can soak them in water but you will have to re-harden them after. Just let them sit for a day or overnight before packing them close to each other.

Try soaking in hydrogen peroxide. Make sure you have thoroughly rinsed the bleach off first.

Yes, sand dollars can harbor bacteria that could cause illness, so cleaning them is advisable.

Mod Podge should work since it's basically the same as glue and water. Try using Mod Podge on one sand dollar and glue and water on another to see which result you like better.