Official Luthiers Forum!

I've been lurking for a couple weeks and thought I'd post my first question. My apologies if it is an FAQ.

My shop is in the basement of my house in St. Paul, MN. In the summer, it's about 70 deg. F and 90% - 100% humidity; in the winter it's about 55 deg. F and 70% - 80% humidity. In other words, not ideal for lutherie. Most dehumidifiers won't work if the temperature is below 65 deg. F, so I can't even run dehumidifiers in the winter.

I'm sure I'm not the only one whose shop is in a basement. What do the rest of you do about temperature and humidity control?

Thanks.

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John Cavanaugh
Saint Paul, MN
"What could possibly go wrong?"

John, welcome to the OLF. I'm in your neighborhood (Madison) and I know a lot of people here use garage floor epoxy on all the concrete surfaces. It will help but undoubtily you are always going to have issues as you are below grade. Plastic vapor barriers work well on the walls but you will still have to seal the floor. Good luck. Paul

You have to raise the temperature. At 55? you will lower relative humidity
more effectively with heaters than you will with dehumidifiers. Warming
the air has the added advantage that you will be able to move your
fingers. You can find home basement type dehumidifiers that are
designed for lower temperatures as well. Seal the floor, for sure, but
nothing you can paint on is really going to block water vapor.Howard Klepper38618.5794907407

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Howard Klepper
http://www.klepperguitars.com

When all else fails, clean the shop.

I have had no issues running dehumidifiers at those temperatures. In fact, they actually kick out a bunch of heat themselves. I currently have an LG (same as Sears) which works great. I have a hose coming out the back of it that goes to a condensate pump, so I never have to empty the bucket. It can reduce a basement from 70% down to 45% in a matter of a few hours it seems.

If one doesn't work, try 2 of them! I know folks who have done that and it works fine for them. Get the place sealed up as everyone has said, and that will help immensely.Don Williams38618.5366203704

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"I want to know what kind of pickups Vince Gill uses in his Tele, because if I had those, as good of a player as I am, I'm sure I could make it sound like that.
Only badly."

Hi John,
like you, I have a basement shop. I'm in the Boston area with seasons not
unlike yours. I agree with Paul, sealing the concrete surfaces is a help. I
have isolated my shop fairly well and I maintain a relative humidity of
between 45 to 50%. I have a full partition along one wall and the other 3
are concrete with wood paneling over them. I leave a dehumidifier
running year round, although in the winter it almost never kicks on. The
winter is typically drier and the furnace running helps to keep the air
drier. I am curious to know what you are using to measure humidity? With
the numbers you gave, I'm wondering what the annual rainfall is in your
shop? More seriously, 70 to 80% in the winter seems a bit high. Is your
shop floor concrete? Lastly, some of the newer dehumidifiers will work in
lower temperaturers. Paul is right -- isolation and heat are the keys.
Craig

If you have forced hot air, open or place a a vent in the ductwork. And a dehumidifier will produce heat. Good points in previous posts

Get humidity under control before you build! I dehunidify about half the year.

If $$ is an issue to dehumidify the whole room, put your wood in a smaller closet where you can contol it. My apprentice put his first guitar kit into a big plastic tub with a lid. He used "Damp Rid" and a hygrometer to monitor moisture. It stayed pretty steady and didn't have to baby sit it too much. The whole deal was upstairs during April through June. After that he kept it at my shop for convenience sake.

You can do it. Just think "inside the box" on this one.

Or you can move out here to West Texas where our avrage winter rh is 48% and summer is 35% but I didn't tell about the suddun changes in the spring 60-80% one day and 15-20% the next

Just goes to show that all basements are not created equal. My winter months we are in the high 20s to high 30s .... I actually have to run a humidifier in the winter.

and during the summer I am in the 60s, but a dehumidifier does the trick nicely. I just put a garden hose on it to go to the sump pump.

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Brock Poling
Columbus, Ohio
http://www.polingguitars.com

Mine fall right in line with Brock's....humidify in winter, dehumidify the rest of the year, ranges from mid-60's down to around 20 at lowest in the dry winter. One humidifier and one dehumidifier keep things nice. I just need an air conditioner for when the dehumidifier is running. It gets real hot from that thing.

_________________
"I want to know what kind of pickups Vince Gill uses in his Tele, because if I had those, as good of a player as I am, I'm sure I could make it sound like that.
Only badly."

Concrete is essentially transparent to water vapor, and if the water table is high where you are it's going to be a problem. I had to give up the fight in my old house with the rock walls in the basement: the mortar was so soft there was no way to waterproof it from the inside.

DH units do kick out a lot of heat, so if you turn it on when it's warm, it's likely to stay that way.

I've seen poeple put up a 'tent' in the basement. Lay down a plywood platform on sleepers, with a vapor barrier under the ply. Build up a light framework on that deck and cover it with plastic. Weatherstrip the door. Make it big enough to hold your work bench, with room to swing a cat all around. Put the DH in the tent, and keep all the wood you're working on, or about to work on, in there unless you need to run it across a machine that's not in the tent.

Years ago I talked with George Bowden in Majorca about humidity. It's only really dry enough to assemble bodies for a couple of months out of the year there, so he'd spend three or four months making parts and getting everything ready before hand. Then for two months he'd glue things together like mad. Once the humidity rose he'd work on the bindings and finish the guitars up. Romanillos talks in his book about Torres doing something similar: monitoring the humidity and then working whenever it was right.

One of the slickest humidity gauges I've seen was the one Carleen Hutchins had. She cut a strip off the side of a piece of plywood and removed one of the three plys, to leave an eight foot piece of veneer with cross banding on one side. This was fastened to the wall in the garage workshop. In the summer, when the garage was open, she'd get the relative humidity from the weather report, and mark the spot on thew wall where the end of the plywood strip was. After a while shehad the thing pretty nicely calibrated.

Thank for all the responses. I've been using an old hygrometer from a "weather station" kit that I never got around to mounting. A more reliable measuring tool needs to be part of the shop renovation plan.

I hadn't thought about sealing the walls; thanks for pointing that out to me. Raising the wintertime temperature is something I've been meaning to get around to (you know how that goes). And my wife will be glad to know that there are dehumidifiers that work in cooler temperatures. She complains about how long it takes for things to dry in the laundry room and the dehumidifier there conked out recently, so we have to get a new one anyway.

Thanks again for your help.

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John Cavanaugh
Saint Paul, MN
"What could possibly go wrong?"

In the Summer Months I use a dehumidifier in my shop taking out as much as 20 Leters (5 Galons) a day, In the winter I use a humidifier adding as Much as 20 Leters a day. Be glad you only have to have one:)