  This paper experimentally investigates the effect of viscosity on the
outcomes of collisions between a regular stream of droplets and a continuous
liquid jet. A broad variation of liquid viscosity of both the drop and the jet
liquid is considered, keeping other material properties unchanged. To do so,
only two liquid types were used: aqueous glycerol solutions for the drop and
different types of silicone oil for the jet liquid. Combining these liquids,
the viscosity ratio {\lambda} = {\mu}drop/{\mu}jet was varied between 0.25 and
3.50. The collision outcomes were classified in the form of regime maps leading
to four main regimes: drops in jet, fragmented drops in jet, encapsulated
drops, and mixed fragmentation.We demonstrate that, depending on the drop and
jet viscosity, not all four regimes can be observed in the domain probed by our
experiments. The experiments reveal that the jet viscosity mainly affects the
transition between drops in jet and encapsulated drops, which is shifted
towards higher drop spacing for more viscous jets. The drop viscosity leaves
the previous transition unchanged but modifies the threshold of the drop
fragmentation within the continuous jet. We develop a model that quantifies how
the drop viscosity affects its extension, which is at first order fixing its
shape during recoil and is, therefore, determining its stability against
pinch-off.
