[kiowes]

I use Bicarbonate of Soda (NaHCO₃) in my washing machine for my clothes as an alternative to commercially available washing powders. Whilst living in London, and thus in a "hard water" region, I read that converting NaHCO₃ into Sodium Carbonate (Na₂CO₃) would dissolve better in "hard water", but I have since come to find that all it does is collect and crystalise on contact with <30ºC temperature (i.e. cold) water.

The Crystals can be coaxed back into mixing with water if the water is heated up (I usually wash my clothes on a 40ºC cycle anyway), but wanted to know why they crystalise?

nb. I convert my NaHCO₃ -> Na₂CO₃ in the oven at 230ºC for 1hr.

[Enthalpy]

Could the crystals possibly be calcium carbonate?