An unblocking roller for removing excess material from the openings of cells of a honeycomb core is disclosed. The unblocking roller includes a cylindrical core having a center axis and a plurality of clusters each comprising a plurality of bristles. Each of the plurality of bristles of each cluster is coupled to the core at a first end and projecting outward from the core. Each bristle projects a minimum of a first distance from the core. Each cluster is separated from adjacent clusters by at least a second distance that is at least 20% of the first distance.