Humidity levels for building

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rideak1

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Greetings All,
I am embarking on the great adventure of building ukuleles. I began building a stew mac tenor and got the body put together and it looked beautiful. I screwed up the neck and had to replace it and while I awaited the new neck I put the body in a foam case in the closet. When I took it out it was twisted significantly. I am now building a new uke at a luthiers shop. He told me that I needed to build in a place that was around 37% humidity. I live in San Francisco and getting that dry without monitoring doors and windows, yelling at the kids when they forget, and running a dehumidifier full stop. Will be problematic. How much should I worry about the humidity of my building environment?
 
I too live in the SF Bay Area. I build at a high of 45% to a low of around 35%. If you get higher than that I believe you need to mitigate the humidity. You don't need to worry about leaving the door open during the day unless it is raining or foggy here in the SF Bay Area.
 
I aim for 45% but im happy anywhere in the 40-50% range
 
I use an expensive little tool called a Moisture Meter. It has two pin contacts that are slightly stuck into the wood to measure the moisture between the contact points. I do this in several locations on the piece of wood I want to use.

rideak1 said:
How are you measuring moisture content? Pins or no?
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Michael Smith said:
I too live in the SF Bay Area. I build at a high of 45% to a low of around 35%. If you get higher than that I believe you need to mitigate the humidity. You don't need to worry about leaving the door open during the day unless it is raining or foggy here in the SF Bay Area.
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Thanks for the input. I live in the sunset district of San Francisco so fog is a constant. I'm going to try a dehumidifier and see how consistently I can keep my basement area at 45% for a week then move my wood there and build in mid-late May (I think)
 
I live in a high humidity environment as well. I have a large dehumidifier in my building room (also where I store wood to use for the next few years.) I keep it at 45% RH. Rather than try to dehumidify the entire basement it might be easier to keep the RH constant if you isolate a room that you are going to build in from the rest of the workshop. You can get by with a surpassingly small room if it's designed right and all you're going to do is build and store wood in it. All of my "dirty" work, resawing, neck shaping, etc is done in an adjacent room. It's important to seal the build room as best you can including the floors (with concrete sealer for cement floors), and the walls and ceiling with Tyvek. Once you get the room down to your target RH it's relatively simple to keep it there. But it could take a week as you extract many gallons of water.
 
Moore Bettah Ukuleles said:
I live in a high humidity environment as well. I have a large dehumidifier in my building room (also where I store wood to use for the next few years.) I keep it at 45% RH. Rather than try to dehumidify the entire basement it might be easier to keep the RH constant if you isolate a room that you are going to build in from the rest of the workshop. You can get by with a surpassingly small room if it's designed right and all you're going to do is build and store wood in it. All of my "dirty" work, resawing, neck shaping, etc is done in an adjacent room. It's important to seal the build room as best you can including the floors (with concrete sealer for cement floors), and the walls and ceiling with Tyvek. Once you get the room down to your target RH it's relatively simple to keep it there. But it could take a week as you extract many gallons of water.
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Thanks for the feedback! Your work is amazing! It's an awesome resource to have suggestions from such accomplished artists!
 
San Francisco Sunset District, must have been where Mark Twain was staying when he made the comment "the coldest winter I ever had was the summer I spent in San Francisco. He could have added moistest too. You will definitely have to run a dehumidifier. Basements can be problematic as well if they are not well built. If you have a drain in your basement you will want to run a hose from your dehumidifier so you won't have to empty the bucket every day. If you are unable to dehumidify a sufficient area to work in and the concrete in your basement has not been sealed I have been successful sealing large areas of concrete with two part epoxy paint.
 
As an amateur builder I would like to offer a different perspective on this question. I live along the ocean in Northern California with a similar environment to the original poster. I build ukes in all seasons of the year and I have never had a problem with cracking, warping, twisting, etc. (Yet.) I do not build in a controlled environment. I do let the wood I purchase equilibrate to my shop before using it however, but I think one can successfully build a ukulele without fancy dehumidifiers/humidifiers, epoxied floors or expensive specialized tools like the moisture meter. More important to the amateur, maybe one-off builder, is to control what he can control like constructing a structurally sound instrument with the tools and environment at hand. I say just build the damn thing and get on with it. Don't get all hung up on the perfect set-up with the all the perfect tools.

That being said, the professional builder does need to control all the variables as best he/she can because the product needs to be consistent and stable. People are paying money for these instruments and all precautions need to be taken into account. The amateur has a lot more latitude. Sure, I would love to have the perfectly controlled environment, but is it absolutely necessary to build a sound ukulele that won't fail? I don't think so.
 
I find it's a whole lot easier to remove the moisture from the air than to put it back in. I have my dehumidifier set up to drain into a sink.

Here in New England, if I built a uke in August in an uncontrolled environment, come January I'd have sharp frets and cracks.
 
As an amateur, you don't have to worry about anything, corect. If down the road the uke leaves the area it was made and goes to an environment that is way different, the uke will suffer. This happens all the time with imports, it can ceratinly happen here. If the amateur doesn't care about longevity, more than likely no one will care if it should fail. Fixing these kinds of instruments is no different than fixing a brand name instrument, it may happen sooner than later.

sequoia said:
As an amateur builder I would like to offer a different perspective on this question. I live along the ocean in Northern California with a similar environment to the original poster. I build ukes in all seasons of the year and I have never had a problem with cracking, warping, twisting, etc. (Yet.) I do not build in a controlled environment. I do let the wood I purchase equilibrate to my shop before using it however, but I think one can successfully build a ukulele without fancy dehumidifiers/humidifiers, epoxied floors or expensive specialized tools like the moisture meter. More important to the amateur, maybe one-off builder, is to control what he can control like constructing a structurally sound instrument with the tools and environment at hand. I say just build the damn thing and get on with it. Don't get all hung up on the perfect set-up with the all the perfect tools.

That being said, the professional builder does need to control all the variables as best he/she can because the product needs to be consistent and stable. People are paying money for these instruments and all precautions need to be taken into account. The amateur has a lot more latitude. Sure, I would love to have the perfectly controlled environment, but is it absolutely necessary to build a sound ukulele that won't fail? I don't think so.
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The humidity where I live has a daily variation between about 85% in the morning to 45% in the afternoon this time of year. Not having a dehumidifier, would it be better to do my gluing in the afternoon when it’s dryer?
 
Dougf said:
The humidity where I live has a daily variation between about 85% in the morning to 45% in the afternoon this time of year. Not having a dehumidifier, would it be better to do my gluing in the afternoon when it’s dryer?
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Evening would be better. Give it as much time in the low humidity as possible. Put your back/soundboard in a sunny window to dry further over the course of the day. You can also put things in the oven, and periodically turn it on to keep it warm. Don't overdo the heat. Put a wood hygrometer in with your ukulele parts, to monitor the humidity.

Here's mine. The numbers are wrong, but after a few years of watching it, I don't really need numbers to know what's a good position for gluing. Made from two strips of spruce glued together. One cross grain, and one long grain. Then thin it down until it's flexible, and it will bend quite a lot as the humidity changes and causes the cross grain side to expand/contract.
 

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Dougf said:
The humidity where I live has a daily variation between about 85% in the morning to 45% in the afternoon this time of year. Not having a dehumidifier, would it be better to do my gluing in the afternoon when it’s dryer?
Click to expand...

That's the exact humidity swing we have here, year round. If you don't have a dehumidifier I would at least build a dry box to store your wood for your upcoming builds and any for work in progress. Once the humidity drops (in the early afternoon) to the desired level you can pull your uke out of the dry box and work on it. The most critical stages of course will be the gluing up of tops, backs, bracing, etc. Sanding, finishing, carving, etc can be done without too much regard for humidity.
Because I am entirely on solar power I can not have my A/C or dehumidifiers running at night and the humidity in my build room rises to about 55% overnight. (I keep it at 45% during the day). So at the end of the day all of my work in progress is stored in a sealed closet that I build that has a mini dehumidifier (Eva-Dry) that only consumes 45 watts of electricity. That keeps it at 40% to 45%. The same thing can be done with a closet heating rod, light bulb, etc. It's big enough that I can also store enough sets of wood to last me a year. These sit on recycled oven racks to allow for good air circulation.
 
Thanks, Dennis and Chuck. Well, I was a bit off on the humidity levels -- I had googled it for Sacramento, which is at the confluence of two rivers, and at the edge of the Delta, whereas I'm at the edge of the foothills and away from the rivers, apparently a different micro climate. According to my hygrometer, it's more like 60%-30% right now. Well, that's 45% on average, maybe I can get a dry box to work with that.
 
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