Borax dust requires sodium flouride, which requires sodium hydroxide. Sodium flouride can be turned into sodium hydroxide and back, but neither appear to have a recipe that doesn't require the other.

This in turn means the chemical scrubber is uncraftable.

Sodium fluoride dust can be crafted in the manufactory from Villiaumite dust

As Andrew says, look for the recipe chains starting from villiaumite and you should be good ;)