  The $t$-colored rainbow saturation number $rsat_t(n,F)$ is the minimum size
of a $t$-edge-colored graph on $n$ vertices that contains no rainbow copy of
$F$, but the addition of any missing edge in any color creates such a rainbow
copy. Barrus, Ferrara, Vandenbussche and Wenger conjectured that $rsat_t(n,K_s)
= \Theta(n\log n)$ for every $s\ge 3$ and $t\ge \binom{s}{2}$. In this short
note we prove the conjecture in a strong sense, asymptotically determining the
rainbow saturation number for triangles. Our lower bound is probabilistic in
spirit, the upper bound is based on the Shannon capacity of a certain family of
cliques.
