Strings last for decades, but don't have eternal live. When a string breaks during tuning (not a copper-wound bass string) and there is time for it, I will mount a new one. This takes about 25 minutes extra. Costs: €30.
For the spinning and mounting of a new bass string a new appointment must be made, see below.
The lowest bass notes consist of one string, wound with copper wire. Higher in the bass the notes consist of two or three copper-wound strings, and the steel strings from the middle to the highest notes are mounted in sets of three. A set of two or more strings for one note is called a unison.
If a bass string breaks it has to be wound identically to the broken example. If a bass string from a unison breaks, this string will be replaced with a newly wound one, but also the one(s) that are still in the piano have to be replaced. If only one string out of a set of two or more is replaced there will be small differences between the new and old strings in the unison, and a false note is heard.
Prices for winding and mounting bass strings differ with the amount of copper used.
One string: around €55
Unison of two strings: around €100
Unison of three strings: around €90