I’m working quietly at my bench today with my hand tools. No loud machines, just a sharp blade slicing through the beautiful wood I get to work with. There’s something special about that feeling and sound.

What makes today even more special is that the windows are open, which almost never happens here. Where I live, it’s almost always too humid or too cold to have them open, except for a few glorious days a year like this one.

I can feel that the peaceful stillness of it all is good for my soul.

But I know the cold air will be here soon, and I’ll have to close the windows and turn on the heat. And as I watch my hands guide the plane down this board, I can’t help remembering one of the most expensive lessons I ever learned.

I walked downstairs to the shop on a Saturday morning just to check on things, like I always do. I had no way of expecting what I was about to find.

All three of the guitar backs I’d braced that week were cracked.

This was late 2003, in my first shop, the one where I built my very first guitar. My wife and I had gotten married the year before, and I needed to deliver at least a guitar a month to keep us afloat.

I had big plans, though. I wanted to figure out how to make more guitars, faster, so things could be a little less of a struggle for us, and one day for the family we hoped to have.

Part of those plans came from our honeymoon. Our family had all chipped in to send us to Maui, and while we were there I called Steve Grimes, a luthier I’d met at a guitar show in 2001 and whose guitars I really admired, and asked if I could stop by his shop. He said I could come for a couple of hours one day.

(My wife wasn’t thrilled about me spending part of our honeymoon in a guitar shop, but she encouraged me to go anyway. She’s been that way since day one.)

Steve had so many guitars in progress at once, all stored neatly on shelves up near the ceiling, over the workbenches. It was a beautiful system, and I came home inspired.

So I built a shelf like it, high up over one of my benches. As soon as it was done, I wanted to start filling it up the way Steve had.

That week I was making a back, and I thought I could be more efficient if I made three, so the next couple of guitars would have theirs ready and waiting. I’d be that much faster from then on.

It was a bit of a gamble, because the wood was an investment and money was tight. One of those backs was cocobolo. The other two were a really beautiful flamed black walnut.

By the end of the week I had all three backs braced up, and I’d even gotten some other work done as well. I put them up on the new shelf and closed up the shop.

I was flying high that Friday. It felt like a breakthrough.

The next morning they were ruined. Every one of them.

It didn’t take me long to figure out why.

We’d had a sudden cold snap, and the heat had kicked on. The heat in that old house was really, really dry, and one of the heating vents blew straight up into that top corner of the shop.

It had never mattered before, because I’d never kept wood or guitars over there. It didn’t even cross my mind when I built that new shelf. By the time that air reached the rest of the room, the humidifier on the other side of the shop had balanced it out.

That’s the part that still gets me. I thought I had the humidity covered.

I had a hygrometer, and it said 50%. I had a humidifier. I’d checked the moisture content of the wood before I ever started.

But the hygrometer and the humidifier were across the room, and they were telling me about the air over there.

Up on that shelf, the dry air blew across those thin backs all night and shocked the moisture right out of them.

A loose plate might have just shrunk. But a braced back can’t move freely, because the braces are holding it. So when it tries to shrink, it has no choice but to tear itself apart.

What went through my head was, what are we going to do? How was I going to make up for those back sets, and that week, and the guitar that wasn’t going to get delivered?

None of it was salvageable. I had to buy new wood and start over. Unfortunately, I learned the lesson on three instead of just one.

I made some big changes after that.

I closed those heating vents and never opened them again, and heated the shop with a small heater instead. (That turned out to be better anyway, because it kept the shop’s dust out of the whole house’s heating system.)

I started keeping hygrometers in several places around the shop instead of one, because I’d learned the humidity in one corner can be very different from another.

I paid much closer attention to where the humidifier sat, where the hygrometers were, and most of all where I kept anything vulnerable.

And those lessons eventually led me to design and build my luthier’s cabinet, which is where every guitar I’m building lives even now, over two decades later.

It protects them from a lot of things, and it cushions the humidity shocks, like when someone leaves the door open on a freezing cold winter day and that bone-dry air floods into the shop.

It’s taken so much stress off of me over the years.

Looking back, if I’d asked Steve about those shelves while I was standing in his shop, I’m sure he’d have told me everything he was doing to keep those guitars safe up there. The thing is, I didn’t know what I didn’t know back then. When I was younger and just starting out, I had no idea how important humidity was. I thought it was as simple as keeping the shop at 50%.

Now, after 30 years, I’ve realized it’s one of the most fundamental things you absolutely have to understand to make guitars that are stable, and that play and sound their best for many years to come.

Those cracked backs are an extreme story. The more dangerous things are the ones that go unseen, under the surface. They can keep a guitar from ever being someone’s favorite, no matter how hard you worked on it. There’s quite a bit more to it than keeping a number on the wall.

And it works both ways: winter’s dry air is only half of it. Come spring and summer, it’s too much moisture instead, and that matters just as much.

My windows won’t be open much longer this year. Soon the temperature will start dropping, and so will the humidity in my shop.

If the heat is about to come on where you are too, this is a good week to walk around your shop and look at it the way I wish I’d looked at mine.

• Where is the warm air blowing?
• Where is your wood sitting, and the guitars you’re working on?
• Is your hygrometer anywhere near them?

That’s the kind of thing we’re going to dig into over the next few Saturdays.

Next week, I want to start with what’s actually going on inside the wood when the air dries out. But your replies will help me decide where we spend the most time.

So before I write that one, I want to hear from you.

If you’re still trying to get your head around humidity in your shop: What are you struggling with? Has it ever caught you by surprise the way it did me? 🙂

And if you’ve been at this a while and found what works: What do you use, and what would you recommend?

I just ordered a new humidifier to test this winter. The one I’ve used for years has been great, but it’s out of stock right now, and I’m curious what’s working for you.

Just hit reply and let me know your questions, thoughts, and stories.

I don’t know if I’ll be able to reply to everybody directly, but I read every one.

Next week I’ll tell you what I’m hearing. And I’ll use what you share in the next letters, so this series goes where you need it to.

I still build in threes, by the way. It just works for me. Each guitar is at a different point in the build, and each one has its own drawer in the cabinet.

None of them live up near the ceiling.

Sapere Aude · Creare Aude

Tom

P.S. If you want to go much deeper than this, what I’ve learned about wood and water since that Saturday morning is in my Humidity Fundamentals & Advanced Applications course, inside the Luthier’s EDGE, where you can bring me questions about your own shop and your own guitars as you go.