What is the difference between travertine and limestone?

Is travertine a type of limestone?

Yes. Wikipedia defines travertine as a form of freshwater limestone, a sedimentary rock formed by chemical precipitation of calcium carbonate from fresh water, typically in springs, rivers and lakes, and often at hot springs. It often shows a fibrous or concentric structure and comes in white, tan, cream and rusty colors.

Limestone, in the same source, is a carbonate sedimentary rock made mostly of calcite and aragonite. Most was formed in shallow marine environments, by biological and nonbiological processes. Limestone is commonly white to gray, with iron or manganese traces giving off-white, yellow or red tones.

Which is more porous, travertine or limestone?

Travertine usually has the more open structure. Wikipedia gives porosity of fresh travertine as about 10–70%, with hot spring travertine averaging about 26% and ancient deposits as low as 2% where calcite has filled the pores. Limestone porosity runs from 0.1% for the densest rock to 40% for chalk.

Those are geological ranges, not purchase specs. For dimension stone, ASTM sets minimum standards, shown below.

How do travertine's voids affect a bathroom piece?

ASTM C1527 states that voids are a natural characteristic of travertine and should be weighed when judging acceptable variation. It also warns that fleuri-cut (cross-cut) travertine can have a thin layer of stone over a void, a weak point, and that some travertines are unsuitable outdoors where freeze-thaw is frequent.

In a bathtub or basin, the practical points are the inside surface and the rim, where you touch the stone most. Look at those areas on the block before it is carved. Every Pietra Fonte piece is inspected with photos or video before it ships, so the voids and banding are visible to you in advance. See travertine for our own notes on the stone.

Is travertine or limestone better for a bathtub or basin?

Neither is better outright. Travertine gives banded, pitted character and is in our range. Limestone is usually a quieter, more uniform face, but it is not in our current range, so we cannot offer it. Both are soft, both absorb more than marble, and both etch in acid.

• Choose travertine for visible banding, warm beige or white tones and a natural, slightly open surface.
• Choose limestone, if you can source it, for a calmer, even face with fewer voids.
• Choose marble if low absorption matters most. ASTM allows 0.20% against 2.5% for travertine.

For weight, we use about 156 lb/ft³ for travertine and about 150 for limestone, so a travertine tub is lighter than the same marble tub. See the weight guide, the travertine bathtubs and travertine vs marble.

Do travertine and limestone both need sealing?

In wet areas, yes. Great Floors says most limestone sold today has a honed or textured finish that is very absorbent and prone to staining, and recommends a stone sealer, including in showers and all wet areas. It lists a water-based protector for porous stone such as limestone and travertine.

Sealing slows staining. It does not stop acids etching the surface, because calcite dissolves in dilute acid. Wikipedia notes limestone bubbles when dilute hydrochloric acid touches it, which is the same reaction. Keep acidic cleaners and bath products off the stone, rinse after use, and see the care guide. Check product and sealer instructions with the manufacturer.