Dental Alginate Impression Material C302240 Tropicalgin is suitable for making impressions of teeth and oral soft and hard tissues. It is mainly composed of diatomaceous earth, calcium sulfate, sodium/alginic acid sodium, pyrophosphate sodium/sodium phosphate, potassium fluorotitanate, and zinc oxide. It turns red when mixed, orange when operating and positioning in the tray, and yellow when setting in the mouth.