This allows sufficient time for the wax to reach its melting point on the outer edge (i.e., wax closest to the glass).
(This; allows; sufficient time for the wax to reach its melting point on the outer edge (i.e., wax closest to the glass) (the wax; to reach; its melting point on the outer edge)
This the wax
allows to reach
sufficient time for the wax to reach its melting point on the outer edge (i.e., wax closest to the glass
its melting point on the outer edge