  We develop a gluing theory in the sense of Koll\'{a}r for slc surfaces and
threefolds in positive characteristic. For surfaces we are able to deal with
every positive characteristic $p$, while for threefolds we assume that $p>5$.
Along the way we study nodes in characteristic $2$ and establish a theory of
sources and springs \`a la Koll\'{a}r for threefolds. We also give applications
to the topology of lc centers on slc threefolds, and to the projectivity of the
moduli space of stable surfaces in characteristic $p>5$.
