An ink comprising an IR-absorbing naphthalocyanine dye of formula (I) is described: ##STR00001## wherein M is Ga(A.sup.1); A.sup.1 is an axial ligand selected from --OH, halogen, --OR.sup.3, --OC(O)R.sup.4; R.sup.1 and R.sup.2 may be the same or different and are selected from hydrogen or C.sub.1-12 alkoxy; R.sup.3 is selected from C.sub.1-12 alkyl, C.sub.5-12 aryl, C.sub.5-12 arylalkyl or Si(R.sup.x)(R.sup.y)(R.sup.z); and R.sup.4 is selected from C.sub.1-12 alkyl, C.sub.5-12 aryl or C.sub.5-12 arylalkyl R.sup.x, R.sup.y and R.sup.z may be the same or different and are selected from C.sub.1-12 alkyl, C.sub.5-12 aryl, C.sub.5-12 arylalkyl, C.sub.1-12 alkoxy, C.sub.5-12 aryloxy or C.sub.5-12 arylalkoxy; and W is a sulfonic acid group, including salts thereof.