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I live in an environment that changes dramatically in humidity and temperature. What atmospheric control equipment do folks in similar situations use to keep their wood stable during construction in the shop? Humidifier, dehumidifier, air conditioner, heaters?

I imagine this is not cheap to control but that not controlling it would be a bigger problem.

Thanks.

$200 dehumidifier and a wood stove. Also, my shop is well insulated.

Hi Peter and I see that this is your first post on the forum so here's a big welcome as well!

At the risk of sounding like a broken record (remember records, I still have all of my vinyl and Neil Young was right, they do sound better to me too....) I always advise new guitar builders that job one is determining and implementing an environmental solution for your shop.

So my hats off to ya too for the excellent question.

I use all of the above, heaters (furnace), AC (my home's central system), dehumidifier in the summer, and 3 - 4 humidifiers in the winter with only one needed in my shop. My shop was purpose built for guitar building and my home was even selected because it was a perfect basement, built in sand, that happened to have a nice, new house already on top....

I walled off about 400 square feet in my very dry basement and put R-13 with a vapor barrier in the walls, even the interior walls. Although I need to humidify in the winter and dehumidify in the summer the units barely have to run to keep me in the target zone of 42 - 48% which is pretty much the standard for guitar f*ctories.

Even before designing or outfitting your shop though please know that digital hygrometers suck.... We have tested most of them and they can be WAY off regardless of what some folks may think about what ever digital that they use. There is also an issue of "range" with digital hygrometers where even if you find one that tests well it may only be accurate in a certain ten point range and way off in other ranges.

Sling psychrometers are the way to go or any variant on a "wet bulb" test. Once you have a "standard" you can use it to find the error in something more convenient such as an Abbeon which is an analog wall unit that I have and like a great deal.

Now not addressing RH concerns and temp too can be problematic in both building and the ability of your prized creations to withstand the abuse that future stewards will often subject instruments too not to mention RH swings and seasonal changes. What can result is everything from cracking to dimensional instability that can pretty much render an instrument useless.

We regulate temp not only for we human bags of mostly water but so our glues and finishes have a temp in the desired range for proper curing. Fortunately this range is exactly what we humans tend to like too so my shop is always 72F.

I'm also in the repair business and we have a very busy three Luthier shop in Ann Arbor and this last winter was the very worst in recorded history for us.... As such we are up to our elbows in cracks (no jokes please, well maybe a few...). All of these instruments, often valuable instruments, cracked because the current stewards aka "owners" did not understand that wooden musical instruments need to be humidified or did not care...

As such our 900 square foot shop is also strictly environmentally controlled to the same ranges that I mentioned above. We don't want a client's instrument that is not cracked cracking in our charge. We also use the humidity in our shop to creatively swell cracks shut, glue and cleat, and everyone is happy.

I hope that something here helps. It may look difficult and some shops can be very difficult to find an appropriate environmental solution for but the alternative is to have your heirloom creations self destruct. One friend of mine did not address the RH issue and on his very first instrument and AFTER the finish was sprayed and now curing cracked across the front in the middle of the night and the noise was so very loud that it woke him up.

So perhaps add the idea that you will sleep better at night too if you continue to approach this as you already are, very responsibly and with priorities that will serve you well.

Hesh, I beg to differ on the hygrometer front, with the caveat that inexpensive digital hygrometers suck. I have a Lufft C200 digital hygrometer/thermometer that is more accurate than any sling psychrometer. A sling psychrometer is only as good as your ability to keep the period of your sling consistent. It also varies as the wet bulb loses moisture. I've taken measurements that varied greatly and I'm pretty steady. Now my hygrometer cost around $300, but its worth every penny.

My workshop is actually a former NASA space capsule. It's airtight nd fully temperature and humidity controlled. It's quite nice actually!

Seriously though, I live in Flori-duh. All I worry about is humidity, it's never too low and always high outside. I have an air conditioner too. I measure the level with a high quality calibrated/certified hygrometer and adjust accordingly.

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Old growth, shmold growth!

The key is high quality. None of the cheap digital hygrometers will be accurate over a broad range of humidity. Most are off by more than 10% most of the time. You can get fairly inexpensive analog hygrometers that are adjustable, and when calibrated, they do fairly well. I have a couple I got at Woodcraft and calibrated myself, and both do a respectable job of staying close to my Abbeon, which I check regularly with a wet/dry bulb set up in my shop.

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Waddy

Photobucket Build Album Library

Sound Clips of most of my guitars

Actually yes when my certified hygrometer says 50% the dehumidifier says 40% and the ten dollar one I got on eBay says 35%.

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Old growth, shmold growth!

Thank you for the welcome and responses.

Maybe I'm just too green, ignorant, and/or optimistic but I was hoping someone would suggest a fully automated system. I know I will not be able to monitor the thermometer and hygrometer daily and adjust the the heater, air conditioner, dehumidifier, and humidifier manually as necessary. That seems like something that could be automated and even should be automated. There would be days, and sometimes even weeks, where I'd be away and I'd like to have the shop atmospheric control system on autopilot (perhaps even with a backup generator connected so things are ok during short power outages.) Does such a system not exist?

No disagreement David and I am aware of the Luffts - excellent hygrometers!

In all the years here on the OLF though when folks speak of digital hygrometers it's nearly always been some Radio Shack POS or big box store offering intended to fit the bill generally speaking but never intended to be a "lab standard..."

Honeywell and others also make digitals in the $1,500 range and up that are very accurate but also not at a price point that the new builder who just secured his first kit from LMI is going to tun out and purchase either....

Regarding wet bulb tests, readings, etc. I'm sure you are pretty steady too as are we and that variance that you see is to be expected. Expected you say - sure simply the breathing of we humans in the area of the test or someone moving across the room will change the readings to some extent and wet bulbs are accurate enough to pick this up. So we take multiple readings and average them.

Peter, a fully automated system would be very expensive. But perhaps, unnecessary with the caveat that you have to be available during the transition periods in the spring and fall.

For dehumidification, most of the cheap ones have poor humidistats that cannot be trusted. I suggest the Thermastor Santa Fe, with the outboard condensate pump. Although it doesn't have a digital readout (only a unlabeled dial) it doesn't take much time to dial it in. They are pricey, but they are better at dehumidifying at the temperatures we build at which are at the low end of efficiency for dehumidifiers. They also draw the same amperage as your average Home Depot 50pt units, but put out 100pts/day and generate less heat in the process.

For humidification, depending upon the size of your space, get a 10 or 12 gallon Emerson (or similar) console style humidifier and build a rolling cart for it with an additional 18" on one side. You're going to hard plumb it to your water supply so you don't have to keep filling it, using a toilet float valve as the control.

Toss the jugs that come with the unit (you won't need them) and plumb in at the bottom of the end of one side (not the bottom of the humidifier, but its side) with some PVC fittings. They make one which screws on from one side and a slip fitting on the other. Get two fittings. Put a ring of plumbers putty around the fitting and push it into the unit and put another portion on the inside and screw it home tight. Make an acrylic 12x12x18" box out of 3/8" acrylic and drill another hole for another fitting. Drill another hole for the toilet float valve and put it in. Plumb connect the two boxes with a piece of 1" PVC and adhesive. Get some 1/4" refrigerator hose and compression fittings and adapters to come off the nearest cold water supply and plumb it to the float valve. Open the valve and allow the water to come up. Inside the humidifier there may or may not be a "fill" line, regardless, you want to set the float valve so it fills within an 1.5" of the slit openings in the back of the humidifier.

Now all you have to do is set the humidistat on the humidifier and the fan speed and you're good to go. You will want to throw biocide in it every week, and depending upon how dusty your shop is, replace the filters twice a season.

With those two things, you're pretty self sufficient. I'm not always in the shop since I split my building with professional audio for theatrical and concert support, so I too can go weeks without getting in there.

Check out on-line sites that sell commercial grade humidifiers and dehumidifiers. Most also sell a Humidistat, into which you can plug the units, and it will turn them on and off based on the need. The trick is that you have to have units that are not dependent on their own switches for start-up. Many with electronic switches will not re-start on their own. The down side is that the commercial units are more expensive. I just replaced my consumer de-humidifier with a commercial grade one this past fall, and the difference is staggering. It runs about half the time and really gets the humidity down to a reasonable level, even in a shop that is poorly sealed. One major difference in the commercial units is that they have real filters on the unit to keep dust out of the system. The one I bought has a washable pre-filter then a high effeciency accordion paper filter too. It actually qualifies as an air purifier in addition to being a dehumidifer. It moves about 150 cfm. Not a dust collector but much more air than the consumer versions.

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Waddy

Photobucket Build Album Library

Sound Clips of most of my guitars

Hello Lads and Lasses of the OLF....this is an interesting topic and one that has fascinated me for a long time....I built myself a dedicated dry room and equipped it with a dehumidifier early on as it was the only way I could see of proper control....Hygrometers are also an interest of mine and I have been wondering for a while now how I could be CERTAIN that they are telling me the truth...So I looked into various ways to calibrate them and got some expert help and advice to better understand the subject....I posted my findings on the ANZLF here....http://www.anzlf.com/viewtopic.php?f=1&t=6123

Cheers

John AKA WoodRat