Stem Fitment Fluctuation (Humidity Related?)

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bluegrassbrian

Preferred Member
Aug 27, 2016
2,021
439
To preface, I keep my pipes and ephemera in my basement. It's unfinished but furnished. The temperature stays pretty consistent but the humidity fluctuates depending on the outside weather.
Within the last month humidity levels have increased. In that same period I've had 3 pipes that normally have snug stem fitment loosen up. Like, the stem removes effortlessly.. almost falls out.
2 Dunhill Shells, and an almost 100 year old Reiss-Premier.. coincidentally all black Sandblast.
Now it seems to me that logic would dictate higher humidity would lead to TIGHTER stem fitment, not LOOSER.

None of my other pipes have changed noticeably.
What's going on here?

 

sasquatch

Preferred Member
Jul 16, 2012
978
21
High humidity (ambient) will make the wood swell a little. Therefore the entire mortise expands (think of the iron ball/ring experiment where if you heat the ring, it will pass over the ball, but if the ring is cold it won't fit).
"Why does my pipe stem get tighter if I smoke it?" well, same thing, the wood expands, but only the wood INside the mortise, the outside of the pipe does not get bigger, so there is a tightening effect very locally on the tenon when you smoke a pipe.
So a real dry pipe will be a tight fit, a pipe in high humidity will be a loose fit, and a recently smoked pipe, paradoxically will be a tight fit as well, temporarily.

 

bluegrassbrian

Preferred Member
Aug 27, 2016
2,021
439
That makes more sense.

I wasn't considering that high humidity would affect the entirety of the wood, not just the inside of the mortise.
For a pipe to be that radically affected it seems perhaps the briar would have to be very well cured and porous at the microscopic level.

 

craiginthecorn

Preferred Member
May 8, 2017
1,141
71
Sugar Grove, IL, USA
Yeah, it's counterintuitive, but true. Humidity expands the entire mortise, making stems loose. I have sometimes used low heat for extended periods as part of a process to eliminate mildew smells. Of course, this dries the briar and shrinks the mortise as a consequence. I always need to wait at least a week for the briar to rehumidify in order to re-mount the stems safely.

 

mso489

Preferred Member
Feb 21, 2013
26,237
435
I've had stems loosen and then tighten nicely on their own, from humidity I assume. These are well-broken in pipes that have never had loose stems before or since.

 

anthony416

Member
Sep 30, 2016
239
1
There are many variables that could come into play depending upon the combination of heat/humidity, including the different coefficient of expansion of two dissimilar materials.

 

franklyn22

New member
Aug 10, 2017
22
0
I've had this same thing happen before too but I always thought it was due to the pipe being cold. It was always pipes that I had not smoked in a few months. I always just smoked them again and everything tightened back up like it never happened.