We just finished two weeks of Santa Ana winds, that get the humidity down in the teens. I had a humidifier going down in my shop the whole time, the flutes were in humdified containers, the humidity still fell to 30% in the containers, with wet rags, real dry! But now it is back up to 45%, hurray! 
Looking out of my window at the grey, grim, drizzly, damp, chilly, miserable British autumn day, I wonder what all the fuss is about…
I’ve no idea what the humidity would be, but the SAD factor is stratospheric! Can that affect flutes as well as their owners?
Ah British weather… hopefully that doesn’t wet your whistle!
When I played my ebonite RC&Co piccolo in the drizzle on the parade at Lorient last August, it went green after! (It has gone back, more-or-less, to black since.) Funny rain in Britanny! My boxwood-&-cow-horn pibgorn didn’t seem to mind, though.
As for wetting my whistle, nah, I have to do that myself. Proper West Country farm cider for my Zumerset made Swayne boxwood high D, of course! Forget Henke’s distilled ash-tray washings - you can’t beat a drop of proper scrumpy! It makes the brass-work shine nicely! And makes me forget the SAD (amongst other things…). Unfortunately, I’ve just finished the 5 gallons I brought back from Devon at the tail end of August 
- I drank the last 1/2 pint last night ( 
).
In the absence of decent cider, Guinness has to suffice…
Only thing wrong with good cider for the flute player I reckon is its tartness. It certeainly screws up my embouchure. Guinness is much better, but Jamisons is best. But I do like a cider when I’m not playing!
Now Jem, is there still a Dartington Centre for Oral Tradition? I went there in 1974 to interview Peter Kennedy. One of the less common ways they employed to fund themselves was selling Scrumpy, brewed on the premises, I was told. I distinctly remember having an 'alf and 'alf on Peter’s advice, as the Sweet was “too sweet” and the Dry “too corrosive”.
Getting back to the topic (hic, now what was the topic?), it’s of course precisely because of the dramatic difference between English weather and almost anywhere else we have so much trouble with cracked English flutes. A London-made 19th century lined cocus flute is pretty much doomed to crack anywhere else in the world. I imagine they almost all crack in England these days, with air conditioning and central heating to contend with. Seems counter-intuitive, but your old flutes are probably better off in the potting shed than in your lounge!
Hopefully modern flutes will do better. Blackwood is stronger than cocus, and hopefully most makers will have got the message that the wood cracks because the metal won’t allow it to shrink. I’d be happier though if they told us what strategies they were employing to counter that basic mis-match in characteristics.
I’d second Dave Copley’s advice (above) about keeping lined flutes somewhere above 50%. But do get a hygrometer - it’s very easy to overdo it and end up with mould (which might present a health hazard) or even loosening the tuning slide and leaving you with a displaced lining, which can have ghastly effects on tone and responsiveness.
Terry
No problem I’ve ever noticed, and I like it dry! Long practice…There’s NOTHING “wrong” with good cider! 
A well balanced dry cider, though acidic, should not cause lemon juice type tongue drying and face crinkling. That said, some “rough” ciders are aptly so-called!!!
Dunno. Never heard of it, and I lived near there in the mid 70s - was in secondary school at Totnes and went to concerts etc. up the hill at Dartington Hall. I’d have been in school (aged 15) coming up for my O Levels that summer when you were there! Dartington College of Arts is being closed down currently and merged with/moving to Falmouth, and I’d guess it would have been part of that if it was still going. They sell exorbitantly overpriced farm ciders at the Cider Press arts and crafts centre commercial side-kick of Dartington at Shinners Bridge, but despite the name, haven’t made cider there so long as I remember.
I met Peter Kennedy myself a couple of times in his last few years - he was living in Gloucestershire and playing in a band with my old fiddling chum Bene Hall (who introduced me to ITM…). Fine singer and melodeon player.
I’ve met two cracked Hammy blackwood heads in the last two years and heard of a couple more! No disrespect intended, just a fact.
On topic, as I’ve noted before, when I visit my parents in southern Spain, I keep the flutes I take in Tupperware boxes with a piece of damp kitchen roll on a jar lid in with them - makes their surfaces go tacky and the keys tarnish rather swiftly, both silver and German Silver, but does save the wood from dessicating.
And keeping the flute in its padded wooden case isn’t sufficient to protect it from dryness? (Sorry if I missed someone’s answer to this already, I was sitting a the back of the class watching the elections and lovin’em! but back to my point…)
No. Leastways, not the extremes we’re referring to. Not unless it has an airtight seal and you keep some kind of moisture reservoir in it - and get mouldy velvet!
Well Terry, I finely got a flute returned that cracked. The flute was made of nicely seasoned Blackwood, Terry Mcgee style cork lined slide, unlined head, supporting silver rings, the works! It still cracked. I think that it must have been stressed by extremly low humidity, say 10% for a long time. Maybe the previous owner could tell us the story?
Not to decry Terry’s design, as I think this is the best design for preventing cracks, but it is no subsitute for keeping the flute in a sutible humidity! 
That is what delrin is for, those that don’t want to take the time to humidify there flutes…
It’s possible, but you’d want to ask yourself the question - what was the mechanism that caused the crack? If we imagine a hollow cylinder of wood - a headjoint - and we reduce the humidity, it will shrink. But why would it crack? If there’s a metal tuning slide inside it, clearly yes. But if not, why?
Don’t forget that there are many mechanisms that can crack flutes, e.g:
- Shrinkage onto a metal liner. Cracks follow the grain. Often seeks out a weak spot, such as a timber feature, or the embouchure hole.
(Doesn’t have to be a liner of course. A delrin stopper with not enough space around it is also an immoveable object. Location of the crack will give it away.)
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It got trodden on. Cracks follow the grain unless the damage is immense, whereupon it might cut across the grain like a snapped school ruler.
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Too much water soaked in from the inside (left unmopped, not oiled.) Cracks are often “angry”, like eruptions, cutting across the grain. Crack is usually a bit downhill from the embouchure hole.
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Seasoning fault. Essentially the same as the previous. Instead of dry wood getting too wet inside, it’s wet wood getting too dry outside. Usually picked up during making.
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Timber fault - cracks follow the fault.
There may well be others.
If there was excessive shrinkage, I’d expect the rings to fall off first, which is usually enough to alarm most owners!
Terry