HUMIDITY LEVELS

[Alexam]

The dehumidifier I have purchased has settings of 40%-50%-60%, but I have no idea what this means in terms of keeping timber in my garage dry enough.

I was going to ask for help, but as I was writing this, I was also searching on my other screen for information, which I have now found.

This may help others to understand http://www.woodweb.com/knowledge_base/I ... _Shop.html

I have now printed an enlarged size of this for display in the shop
58-64 RH - 11% MC
52-58 RH - 10%MC
46-52 RH - 9% MC
39 -46 RH - 8% MC
32 -39 RH - 7% MC
25 -32 RH - 6% MC
19-25 RH - 5% MC


Malcolm

 

[Ttrees]

Here's a cool home made hygrometer you can make yourself .
You just need to find a hygrometer to take settings off .. (hammer)
Luthier Robbie O Brien has some other videos on the subject too .

I dont have permission yet to post links ...so its a copy and paste jobbie

YOUTUBE Luthier and Instructor, Robert O'Brien, discusses the importance of recognizing changes in relative humidity as you build your guitars. He shows how to make a simple but very accurate home made hygrometer for this purpose.


Good luck
Tom

 

[MIGNAL]

I wouldn't take too much note of those dehumidifier settings. A lot depends on the particular space - size and how 'leaky' it is. I have a decent Ebac house dehumidifier and it only manages to drop 7 % RH going full tilt, constantly on. That's in a well insulated attic space. I've even sealed all around the door leading to the room. Of course it's better than nothing though. You really need an industrial dehumidifier to give better control.

 

[Alexam]

Thanks Guys, so ideally, what should the workshop/garage be maintained at if possible? Does anyone have a temp/humidity reader they can recommend?

Malcolm

 

[Sgian Dubh]

If you can maintain the RH between about 40% RH and 60% RH, with 50% RH being an average between those extremes, those numbers match the RH range wood destined for a habitable environment (house, office, etc) in most parts of the UK is likely to experience, i.e., typically somewhere between about 40% RH (winter) and 60% RH (summer).

I can't hazard a guess at how easy it would be for you to control the climate in your workshop. I should also point out that it's not absolutely necessary to control the RH particularly closely to the figures I've given to successfully build stuff - you just need to know what to allow for future wood movement if your workshop environment is quite different to what I've described.

I use an economically priced hygrometer like the one in this link. It's not accurate to the same degree a scientist might look for, but it's good enough to provide 'useful' readings. Slainte.

Source: http://www.thermometersdirect.co.uk/eti ... 0wod9a0FOA

 

[sunnybob]

now you know just one of my problems. Humidity here goes from 45% to 98% on a weekly basis depending on wind direction, but with no relation to temperature. But i put up with that for the sunshine (g)

 

[MIGNAL]

The problem with some of the cheaper hygrometers is that they aren't necessarily that accurate. Even if they are they don't always stay that way. I bought 3 digital units before I found one that was within 3 or 4 % , tested against a sling psychrometer and the salt test. One of them was out by a huge 15% RH, the other by 9%. I use Potassium Carbonate (ebay) to test it for 43% RH. You can use common salt but that's testing it against much higher humidity.
Some makers of hygrometers warn against using the salt test but mine has been through it numerous times and survived.
I've also made a number of the bi wooden strip hygrometers and the one I kept has tracked the digital unit surprisingly accurately for the last 6 or 7 years. It's just a bit slower to react but that's hardly a problem.

 

[Yetty]

Thanks Guys, so ideally, what should the workshop/garage be maintained at if possible? Does anyone have a temp/humidity reader they can recommend?

Malcolm

I'd suggest the "ideal humidity" of your workshop is the same as the final location of the your project - yes?
But since that's always changing, to be practical, I'd aim for the workshop level to be the average of the final location, whatever range that is...
For me, I aim for 60-65% RH in the workshop when there's a project on, then using aclimatised timber and good design practice, there's never been a problem, so far, touch wood....

- what do you think?

 

[Alexam]

All sounds very logical. It was just that some of the timber on shelves seemed a little damp even though the garage is sound. I do put it down to having wet cars in there from time to time, but tgoday I had the heaters on and humidity has come down to 65 so far. Will keep the dehumidifier going and keep an eye on the levels.

Thank you for the help from all of you, much appreciated.

Malcolm

 

[Beau]

What sort of work do you make Malcolm?

If you make external doors and windows I would not worry too much on the other hand if your making complex pieces destined for hot rooms it's hard to make a workshop too dry. If you can make the garage as air tight as possible you will make life much easier for the dehumidifier. We built a large boat in an uninsulated shed but incapsulated the space in a plastic tent and a couple of small dehumidifiers kept RH below 50% in spite of this being up on Dartmoor were outside RH sits close to 100% most winters.

 

[John15]

Malcolm,

You say your stored timber seems damp - you can check it with a moisture meter. I believe it needs to be between 7 and 12%.

John

 

[RobinBHM]

Large joinery companies actually install humidifier systems to control humidity because mostly factories are too dry and the joinery is then too dry and ends up swelling when installed on site.

I have one of those cheapish digital hygrometers at home, it sits on my wife's piano. It seems to range from high 30's to low 60's. Pianos prefer around 45% -50% I believe or they drift out of tune.

Im not sure what is best for people! -probably higher than centrally heated homes I should imagine