longer bath bombs

[phpworm]

What is it exactly that makes a bath bomb last longer? More citrus acid or more baking soda? Or something else?

I notice the ones I make which are 1/2 cup citrus acid and 1 cup baking soda work well however they dissolve very fast, whereas store-bought bombs seem to last much much longer...

Any tips please?

 

[ohsoap]

I noticed my harder ones lasted longer, try adding 1/4 cornstarch.

 

[carebear]

cornstarch, clay, or even milk powder may help, but best of all would probably be a tighter compression. harder lasts longer.

 

[phpworm]

milk powder would probably also turn the water a cloudy white wouldn't it?