Non-toxic alternative to borax for use in slime chemistry?

Question

I understand that sodium tetraborate decahydrate ($\ce{Na2B4O7•10H2O}$) and water is the primary binder for PVA glue based slimes.

We have learned borax is not good for the ground water, or marine life, so I am trying to determine if there is a safer alternative substance that would produce the same cross-linking effect between the protein molecules of the glue and the borate ions $\ce{(B(OH)4)}$ of the borax solution. The hope is a non-newtonian fluid.

If not, is there something that could be added to the slime, to neutralize the borax, making it safely compostable?

Answer 1

Boron's toxicity depends on how much you're making, and how you would dispose of it.

There's some naturally-occurring boron in the environment, and boron is a necessary for many green plants. Borax is commercially available for home laundry use. This Safety Data Sheet states it is, "Readily degradable in the environment."

Therefore, if you're using no more than the quantity used in home-laundry, and if the waste is sufficiently diluted, then disposal through community sewage is reasonable. Since the slime is so thick, sufficient dilution is almost inevitable to get it down the drain.