Editing Limescale (section)

{{Short description|Hard, chalky deposit of calcium carbonate}}
[[File:Limescale-in-pipe.jpg|thumb|Limescale build-up inside a pipe reduces both liquid flow through the pipe and thermal conduction from the liquid to the outer pipe shell. Both effects will reduce the pipe's overall thermal efficiency when used as a [[heat exchanger]].]]

'''Limescale''' is a hard, [[chalk]]y deposit, consisting mainly of [[calcium carbonate]] (CaCO<sub>3</sub>). It often builds up inside [[kettle]]s, [[boiler]]s, and pipework, especially that for hot water. It is also often found as a similar deposit on the inner surfaces of old pipes and other surfaces where [[hard water]] has flowed. Limescale also forms as [[travertine]] or [[tufa]] in hard water springs.

The colour varies from off-white through a range of greys and pink or reddish browns, depending on the other minerals present. Iron compounds give the reddish-browns.  

In addition to being unsightly and hard to clean, limescale can seriously damage or impair the operation of various plumbing and heating components.<ref name=Ullmann>[[Hermann Weingärtner]], "Water" in ''[[Ullmann's Encyclopedia of Industrial Chemistry]]'', December 2006, Wiley–VCH, Weinheim. {{doi|10.1002/14356007.a28_001}}</ref> [[Descaling agent]]s are commonly used to remove limescale. Prevention of [[fouling]] by scale build-up relies on the technologies of [[water softening]] or other water treatment.

Limescale can also affect optic products, such as [[glasses]] and [[mirror]]s.<ref> https://phys.org/news/2022-09-method-limescale.pdf</ref>
[[File:Eifelmarmor01.jpg|thumb|upright|This column in the [[Bad Münstereifel]] church in Germany is made from the calcium carbonate deposits that built up in the Roman [[Eifel Aqueduct]] over several centuries of use.]]