The present invention relates to a method for preparing high-purity terephthalaldehyde which comprises re-crystallizing terephthalaldehyde crystals containing impurities, using an anti-solvent. A lower die comprises a lower curved compressive face, lower recess walls extend contiguous from the lower compressive face at an acute angel to the lower compressive face and define another portion of each cavity. The second processing context is different than the first processing context.