Wörterbuch (en): Hairline crack / Hairline fracture
de: 
Haarriss (m) 
fr: 
Fissure capillaire (f) / Fendilles (f.pl) 
it: 
Fessure (f.pl) / Crepa dell'attaccatura dei capelli
es: 
Fisura delgada (f) / Fisura muy fina (f) 
Cracks up to 0.2 mm wide. Repairing hairline cracks is relatively easy because the damage is not of a structural or static nature.
