Hard as Hull Head Cement(Orm-D) features acrylic polymers to create a rock hard, durable finish. It's a staple for finishing thread heads on flies all over the world. The original formula (blue bottle) and penetrator (brown bottle) both have a brush applicator.
Original formula - A single coat soaks into your thread wraps/materials for an incredibly hard, durable, and glossy finish. Multiple coats quickly build up a larger head.
Penetrator formula - Made to soak into and lock thread wraps without changing surface appearance.
Thinner - Can be used with either formula to bring it back to the original consistency.