When harmful gases mix with rainfall, they form a weak acid that slowly eats away at stone. Marble buildings and sculptures are especially vulnerable — they lose mass over time as the acid dissolves the surface. This experiment tests whether a calcium oxalate coating can protect marble tiles from that damage. Three tiles each weigh 100 grams at the start. One gets no coating, one gets a commercial sealant, and the third gets a coat of oxalic acid that reacts with the marble to form calcium oxalate. All three soak in vinegar for five days while you track the weight each day. The uncoated tile loses the most mass. The calcium oxalate tile and the sealant tile both hold up much better, showing how a protective layer can slow the damage acid causes to stone surfaces.

Acid reacts with marble and dissolves it over time — the same process that slowly eats away at stone buildings and sculptures exposed to acid rain. A calcium oxalate coating may interrupt this reaction by forming a protective layer on the stone's surface. In one test, an uncoated marble tile lost the most weight after five days in vinegar, while a calcium oxalate-coated tile held up much better against the acid.