Low-Cost, Home Synthesis of Vaterite: A Factorial Study of Calcium Source, Temperature, Citric Acid Modification, and Mixing Intensity

This paper presents a low cost, home-accessible method for synthesizing vaterite-type calcium carbonate (CaCO₃) using consumer-available materials and simple household tools. Vaterite is a metastable CaCO₃ polymorph of interest for biomedical, filler, and coating applications, but existing synthesis protocols typically require laboratory-grade reagents and equipment, limiting accessibility for independent researchers. The two required precursors, sodium carbonate (from baking soda) and calcium acetate (from eggshells and vinegar), were prepared in house. A 16-factor design then tested how calcium source, solution temperature, citric acid addition, and mixing intensity affect morphology. Optical microscopy (400×) of the first successfully produced sample (condition 3-D: cooled calcium chloride, citric acid added, strongly mixed) showed small, circular clusters with a flour-like texture consistent with vaterite morphology. Qualitative comparison of the remaining conditions suggests that citric acid addition is associated with finer textures more than mixing intensity, though this remains unconfirmed under magnification for most samples. This is presented as an interim record of an ongoing study. Crystallographic confirmation (XRD/FTIR) and microscopy of the remaining samples are planned as direct follow-up work. The primary contribution at this stage is a documented, reproducible, low-cost synthesis protocol together with one positive proof-of-concept result.