Hi new explorer,
The link is not working for me. So I don't know what you did.
But 'the little rocks' is not something I experienced.
I normally dissolve the naoh in water. Stir it till it is dissolved and then add it to the mix. Check if you used the right amount of naoh.
Did you use other chemicals?
You can put more naphta in but then again you have to evaporate some naphta before you put the naphta in the freezer. Some spice will stay in the solvent.
You can also use glassware with a smaller diameter--> thicker layer
"All is knowing."