Heckel was prompted by composer Richard Wagner to build a bassoon that descended to low A as well as a contrabassoon based on the Heckel model, and Julius Weissenborn would write a complete method book specifically for the Heckel bassoon by 1887. The final major improvements were added to the bassoon by 1905, including lining the wing joint in hard rubber in 1889 and adding the whisper key to the bocal later.