A study has been made of the crystal growth behaviour and perfection of TNT. Depending on the purity and the solvent used, crystallisation from solution yields material of monoclinic, twinned monoclinic or orthorhombic forms. Of these only the monoclinic form was suitable for detailed study by X-ray topographic techniques. The crystals of the orthorhombic form were too small and imperfect for examination.
Seeded growth from ethyl acetate solution yielded lamellar twinned crystals in which the twin density was low. Under ideal conditions, relatively perfect samples could be obtained in which the dominant residual growth defects were stacking faults of Burgers vector
½  and dislocations.