Our editor wrote and posted an article including that some circumstance was ‘putting a damper on’ some company’s activities. While he was at lunch, a colleague asked me if that should be ‘putting a dampener’. After some thought and no research, I said that both were correct, and that I wouldn’t change anything our editor wrote unless is was clearly incorrect.
I asked my Facebook friends what they would say/write, and their answers were basically split down the middle. I did some research and found that damper is used far more than dampener, including in the phrase ‘put a damper on’.
This is complicated by the fact that there are so many forms:
Noun: damp, dampness, damper(s), dampener(s)
Verb: damp(s/ing/ed), dampen(s/ing/ed)
Adjective: damp(er/est), damping, damped, dampening, dampened
Adverb: damply
and so many contexts: mine and marsh air, moisture, vibrations (piano strings and vehicle/machine parts), cloths, enthusiasm and campfire-cooked bread (which seems to be related to all the others, but I’m not sure how).
There are four choices: damp v dampness, damper v dampener, damp v dampen and damp v dampening v dampened.
Dampness has been more common than damp overall since the 1830s (slightly earlier in AmEng and slightly later in BrEng) and can be used in more contexts.
Damper has always been far more common than dampener, with no significant difference between AmEng and BrEng.
Damp and dampen have switched and switched back over time. Historically, the more common form was damp. Dampen took over in the 1970s, but damp regained the lead in the 2000s, both for no reason I can think of. This was led by AmEng; dampen never quite overtook damp in BrEng. This might affect your choice of noun. If your verb is damp, then your noun will probably be damper. If it is dampen, then it will probably be dampener.
Damp has always been far more common that damping, damped, dampening and dampened, but there is a difference in usage. Damping and damped almost always apply to scientific things. Dampening applies to effect(s), system, solution, influence(s), factor, device, rollers and action, and dampened to enthusiasm, cloth, paper, spirits, hair, cotton, sheet, towel and sand – both a mixture of literal and figurative dampness. Damp applies to cloth, air, earth, weather, ground, soil, sand, places, climate and atmosphere – all literal dampness.
Regarding the adjective damp and the verbs damp and dampen, compare moist v *moist and moisten, wet v wet and *wetten and dry v dry. I would have thought that wetten was a word, but apparently not.
I was reminded of a limerick which a major search engine quickly found for me:
“I must leave here,” said Lady de Vere,
“For these damp airs don’t suit me, I fear.”
Said her friend: “Goodness me!
If those pears don’t agree
With your system, why eat them, my dear?”
(Usages from Google Ngram Viewer.)
Never Pure and Rarely Simple 