Monotropism, enantiotropism, and crystallization strategy

Obtaining the thermodynamically stable form in a monotropic system no transformation can take place to another form, and no precautions need be taken to preserve the stable form or to prevent a transformation. 

Obtaining the thermodynamically stable form in an enantiotropic system precautions must be taken to maintain the thermodynamic conditions (temperature, pressure, relative humidity, etc.) at which the G curve for the desired polymorph is below that for the undesired one. 

Obtaining the thermodynamically metastable form in a monotropic system a kinetically controlled transformation may take place to the undesired thermodynamically stable form. To prevent such a transformation it may be necessary to employ drastic conditions to reduce kinetic effects (e.g. very low temperatures, very dry conditions, storage in the dark, etc.) 

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