Can you fix a cracked neck on a guitar?
When the headstock or neck of the guitar starts to crack or break completely, the only option is a professional repair. The bridge (where the strings are attached to the body of a guitar) is another vulnerable area on an acoustic guitar.
Can you fix hairline cracks?
You can repair hairline cracks in concrete with a grout made of Portland cement and water. Add just enough water to the cement to form a thick paste. ... After the hairline crack has been moistened and thoroughly cleaned, apply the grout with a putty knife or pointing trowel.