Humidity

[Bob Connor]

How do you blokes deal with humidity or lack thereof in your workshops?

Here in Victoria our shed hovers somewhere between 40 and 60% RH on most days.

Hot day with a northerly wind it might get down to 30% and when it rains (not often) it'll be in the 90% range.

Just a note for our American mates, we don't tend to get extended periods of high or low humidity in a lot of Australia - unless you live in Far North Queensland like Allen or in the the middle of the Outback. (like Kim ) Most of the population of Oz tends to be concentrated around the coast so things are fairly moderate and temperate.

We tend to wait for favourable conditions for any critical gluing operations like jointing tops and backs, bracing, glueing bridges and particularly gluing tops and backs to rims.

We've had 5 braced tops sitting in the shed for the last week and they really are a good indicator of what the RH is doing - high humidity they'll curl towards the braces - low RH and they'll tend to flatten.

When they are conforming to a 25" radius they're good to glue.

Mind you this sort of environment is great for seasoning wood.

Just means you have to have a whole lot of other jobs when conditions aren't right. Which isn't difficult. I tend to go on a mass production frenzy and make up a heap of fingerboards or reverse-kerfed linings or process back re-inforcment strips out of spruce offcuts.

Or if things are really hot I'll just say stuff the guitar building and make a concerted effort to empty Le Fridge.

Just wondering what everyone else does.

Honeywell didn't have a franchise opened in Cremona when Strad was hammering nails into the necks of his fiddles apparently.

Bob

[Craig]

I do likewise Bob. I find there is always something you can get on with during higher humidity. We have received quite a lot of rain up here this summer , so the humidity has been quite high for a few weeks. It'll soon turn around though . You get to know the weather patterns.Now all I have to do is get some spare time to start building guitars again. ( one million curses ! )

[BillyT]

I could never figure that out! I thought a good portion of Australia was considered subtropical. Waz up wit dat!

[Hesh1956]

Bob I would think that waiting for favorable conditions would be problematic and not just because of the wait or the stock level of Le Fridge.

Although your RH conditions may be favorable the wood will take some time to acclimate to the current conditions. For example, after baking a top I won't use it for at least 2 weeks even though it is sitting in 42-48% RH the entire time, it needs the time to stabilize at the prevailing RH.

Didn't I read here a while back that Matron had lowered the RH range that they keep their shop at?

Any way here in Michigan there are several months of the year where in a single day I may have to use the dehumidifier and/or the humidifier in a single day to maintain the desired range.

One machine turns off and shortly there after the other machine turns on...... but the RH remains in the desired range.

At your high level of production I would think that you need to maintain a stable RH at all times. The potential liability of not doing so could be ugly down the road.

If it were me I would find out what Matron is doing and set my shop up to maintain the same range.

[Allen]

Gee, I wish I had that problem Bob.

[graham mcdonald]

Canberra is an almost perfect instrument building climate. Most days (if not actually raining) RH gets to 40% around 2pm. It is then time for gluing.
An accurate measurement of humidity is good. I have a little digital meter and our electricity supplier has current weather indications on their website for crossing checking. Summers are mostly pretty dry here. I got in a large billet of Sitka from Alaska a few years ago, cut it into 5mm slices and stacked it in my garden shed. It dried to a stable moisture level within a couple of months (stopped shrinking and losing weight)

Most builders I know in Sydney or along the coast have a cupboard or small room fairly well sealed off with a de-humidifier where wood is stored and braces are glued.

It is much easier to build instruments here than in the mid-west of the USA. I suppose it must be lovely in spring and/or autumn, but my one experience of mid-summer in Missouri in 90 degree heat and 90%RH was very tiring and then it snows in the winter!

cheers

graham

[Bob Connor]

Thanks everyone.

I started thinking about this after a discussion with Ray Black who is a fine Mando builder here in Geelong.( He'll hopefully be joing us when he gets his internet connection fixed)

He works on the same premise as Graham, Craig and ourselves in that the humidity changes where we live aren't drastic enough to warrant a complete humidity control system.

He stores his blackwood stash up in the roof of his workshop.

I'm thinking that an insulated cupboard with some sort of RH control is the way to go.

Thanks everyone.

Bob

[Paul B]

They're drastic in Sydney!

It swings all over the bloody place here.

When I was building my first guitar I had the box finished and was working on the neck. The box was just sitting on the bench, tho I normally stored it in a garbage bag with a damp sponge. Suddenly there was a loud CRACK coming from the direction of the box. I immeadiatly looked at the hygrometer; it was sitting at 15% RH. I had come into the shed not 1/2 an hour before and it had been 85%. I shit you not. The top had cracked at the cutaway, it was an easy repair tho.

What had happened was; in the morning the breeze had been coming from the east (off the ocean) and the humidity was high, but then we had a warm front come in from the west (the desert) with lots of warm dry air. So now I know that when westerlies are forcast the humidity is going to plumet quickly.

Sydney is, believe it or not, one of the most humid places in Australia according to the offical figures. Not a good area to be building guitars without climate control. But it's just a matter of watching both the forcast and the hygrometer and gluing when the time is right. I'm finishing up my fourth guitar using this principle and it seems to be working out ok.

[joel]

I've been living in Newcastle for the last 2 years now, and I've got to say that it's the most consistently humid place I've ever lived. I've been keeping track of the humidity in my garage over the summer so far and the lowest it's got was 55% for half a day... before an almighty thunderstorm. For the last two weeks it's been between 70% and 90%. This morning it's a tad above 70%, which is about average.

Now my garage has two roller doors so I can't properly seal it, and since I rent I can't modify the garage either. So I'm in the 'wait for the weather' category by necessity.

The length of my guitar making career has only been the lat two weeks (70% to 90%). I got sick of waiting for better weather conditions to start building. Luckily I'm progressing very slowly, and I've only joined the top, thinned it to 3mm, and yesterday installed the rosette (which needs to be levelled today). So I haven't yet come to humidity critical operations yet like bracing. I'll post some piccies soon.

Is it just me or did everyone else stress about every step on your first build. I'll tell you that starting the router into my King Billy top was bloody nerve-wracking!

[sebastiaan56]

Hi guys,

Paul, Im a lot further west than you, on the escarpment and the swings can be dramatic, but not as dramatic as that. I personally havent had any issues (touch wood... ) but I tend to do carved tops and backs and dimensionally smaller sides.

Great heads up guys, thx

[Paul B]

Maybe that was a one off, you would have copped the same thing that day.

And to be honest I haven't seen a swing as big as that since.

[Paul B]

Joel it's not just you. I think that's why everyones first builds are so slow. You spend more time stressing about it than actually building. Once your confidence increases you'll speed up.

[graham mcdonald]

Humidity control along the coast isn't all that hard. When I lived in Sydney I built a cupboard 2x1m with half of that space a go-bar deck with some storage and a de-humidifier underneath. It was framed up out of 2x4s into a corner and covered with foil insulation (sisalation?). Wasn't totally sealed (which probably would have been better) but worked well with no problems. I would empty the bucket in the dehumidifier a couple of times a week.

Of course, a fully climate controlled workshop would be nice...

cheers

graham

[James Mc]

I have a big old fridge that was earmarked for the dump. I salvaged it installed a 20w light bulb and put a computer fan in the top. I store all kinds of stuff in it that I don’t want getting too damp, welding wire and rods, veneers PC boards etc. I only turn it on in humid weather, which isn’t all that often in Townsville (dry Tropics) but it does the job and didn’t cost anything. I was thinking that if I put in a bigger bulb and thermostat in it that maybe it could be a good way of drying green timber???

[kiwigeo]

I was lucky enough to be building a new garage in 1998 so added a fully climate controlled workshop. A dehumidifier keeps moisture down and during the winter a ceramice panel heater runs around the clock to keep things warm and take load off the dehumidifier.

[sebastiaan56]

"I could never figure that out! I thought a good portion of Australia was considered subtropical. Waz up wit dat!"

Hi Billy,

Aus goes from tropics complete with monsoon, desert yeh a bit of that, down to about 44 South. So think of Mexico to Newfoundland. There arent that many big hills though, so snow is a bit rare. There are rainforest of the tropical, subtropical, temperate varieties and if you want to be pedantic bits of Antartica as well. Most Aussies however live within a few hours of the coast so there is a lot of humidity variation.

Sebastiaan

[Kim Strode]

Hey Bob,

I started my own research on Humidity after your post. Check out this supplier: http://www.dampsolutions.com.au/catalog/index.php

[Bob Connor]

Thanks Kim

I think I might have a use for one of them dehumidifiers.

Bob

[BillyT]

Aus goes from tropics complete with monsoon, desert yeh a bit of that, down to about 44 South.

Thanks Sebastiaan, I keep forgeting how big Oz is!

[Dominic]

I live in the ACT like Graham and most days the humidity is around perfect. But for a bit there in November I think I had quite a few days where it dropped to about 20%. I was creating static and getting zapped all over the place and my braced tops nearly inverted and i freaked. Then a few weeks ago I was working happily away and it rained (rare around here these days) and the humidity shot up to 80% and everything felt soggy.

Hearing Bob say that it is OK for the tops to move around a bit so long as they are glued to the body at around 40% makes me feel more comfortable. But can you ever feel totally comfortable seeing a near inverted top?
Dom

[Bob Connor]

I don't think that anyone feels comfortable seeing them like that Dominic but that's essentially whats going to happen to them when they go out into the real world

Bob

[Dave White]

Dom,

At least you know your tops aren't overbraced

[Dennis Leahy]

Duluth, MN, USA, winter:
I have been running a humidifier day and night for weeks (just to keep the tonewood in my basement from cracking.) The RH has been as low as 24% in my shop. My humidifier is too small, and the best I can do is raise it to about 31% - and that includes occasionally spraying a mist on the floor from a hand sprayer.

It has been very cold here (-20°F / -28°C) lately, so the furnace has been busy making sure the OPEC sheiks can make their mortgage payments. All that hot air is what is drying us out so much indoors. (It's 83% outside right now.)

Similar to Paul's story:
When I lived in Southern California, we used to have desert winds ("Santa Ana" winds) that would occasionally blow in and drop the humidity extremely quickly - like 50%RH down to 10%RH in a matter of a few hours. I actually heard some of my exotic wood cracking before I could raise the RH. I don't want that to happen to my tonewood stash!

And yes, Graham, you're right: much of the central and especially the north central US goes from near-tropical conditions in the summer to near-Arctic conditions in the winter. What the hell am I doing here???

Dennis

[Allen]

I put a dehumidifier in a small bedroom, and I'm pulling out 8 liters of water every 1 1/2 days. They heat the room up a bit when they are running, but it's a lot more comfortable going in to the bedroom to work at 39 degrees 45% RH than it is at 32 degrees and 90% RH out in the garage.

And if I take a top out to the garage to carve braces it will turn itself inside out in a matter of a couple of hours in those conditions. Take it back into the bedroom and it comes back into shape. It's a really unnerving thing to see.

Sorry, I can't help you guys with adding humidity, other than in parts of Canada, away from the wet west coast, to add humidity to the house in the winter to make it more comfortable to live, many people vent their clothes drier directly into the house instead of outside.

[Bob Connor]

It may be un-nerving to see how much these can shift but I think it is
invaluable to actually see it and realise how your instruments will react to RH changes once they are removed from a controlled environment.

Finishes and bindings will slow down moisture loss/gain but they'll still move if left in adverse conditions for long enough.

A spruce top with braces attached would be a great indicator to leave around your workshop to show what your RH levels are doing.

Bob