I can't sayI know the chemistry behind the application of CA to the baking soda but I can say this with certaincy. I have used balsa dust carefully saved from sanding and you cab use it the same way. Poofs of smoke when the CA is applied too! In a pinch you can use cigarette ashes to do the same job. Most know that ashes can be corrosive though I cannot remember if they are acidic or alkaline. Lye is alkaline so I lean that way.

I like the balsa dust best because it is pretty much the same color as the joint but when using it to fill a poor joint I just think its right.

A lot of trouble for a little balsa dust and Baking soda is far easier and cheaper ( no work involved) but all these have worked well for me.

I bet you could use micro balloons in some instances... May not be as strong... Untested

Robert