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| Relative Humidity http://www-.luthiersforum.com/forum/viewtopic.php?f=10102&t=8526 |
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| Author: | Richard_N [ Tue Sep 19, 2006 9:27 am ] |
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Sorry to wade in with another question already ! I have been offered the use of a bit of space in a large workshop. Its an old factory building shared between a cabinet maker and a sculptor. I think its a great opertunity but I wont be able to controll the humidity in the shop. I've been looking through the archives here and at the MIMF and as far as I can see there are 3 options: 1. construct a kind of small room (more like a tent realy - plastic sheeting over a frame) just big enough to store the wood in and glue the braces to the top etc. and put a portable dehumidifier in there. 2. I've seen people talking of storing the wood in a cupboard with a lightbulb that heats it up. (This suprises me since although the RH drops as the air heats up surely the amount of water in the air and wood is the same). They then build everything in an uncontrolled workshop at 70% RH say and return it to the box after working on it. 3.Take a risk , build and see what happens! Ambient conditions are currently around 65% RH (+/-10) at around 25 ?C. Both will drop as the autumn progresses. Which method would you recomend in my situation ? Thanks in advance for your advice |
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| Author: | A Peebels [ Tue Sep 19, 2006 9:37 am ] |
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I would build the tent, or wait for the humidity to drop before bracing the top or back. You can go ahead and carve your neck, thickness and join the top and back, install rosette, bend the sides, and install end blocks and kerfing. Al |
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| Author: | Sprockett [ Tue Sep 19, 2006 10:14 am ] |
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There are a lot of people who use option number 2, that would be my suggestion for you, it takes time for wood to adjust to RH so you should have no problem taking it out and working with it. The ideal goal for RH is 47 (at least that's what I think), what you can do is build a large cabinet and then look at cigar humidistat setups, THOSE people are NUTS about RH. In fact I found one that will keep my shop at a constant RH and all you do it hook it up to a water supply and set the humidistat! this is after years of looking for a good solution, I was just looking in the wrong place :) -Paul- |
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| Author: | Mark Hanna [ Tue Sep 19, 2006 10:32 am ] |
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Paul, tell me more about the setup you use with the water supply. Where and how do I get a setup like that. I'm currently using a dehumidifier which is ok, but the humidifier is a pain in the neck! Mark Hanna |
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| Author: | old man [ Tue Sep 19, 2006 1:52 pm ] |
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Yeah, Paul, share please. I'm looking for THE answer, too. Ron |
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| Author: | Tom Morici [ Tue Sep 19, 2006 5:42 pm ] |
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since you have part of a large space to work in a storage cabinet for your wood and build makes the most sense to me. I prefer 42% at 72deg. This is the average comfort level of living quarters. Wooden items keep in the home, average about 8% moisture content. That said I try to keep my wood and builds at 8%mc. 
Tom |
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| Author: | Richard_N [ Tue Sep 19, 2006 7:10 pm ] |
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Tom, So you're saying that the temperarture doesn't matter as long as I get a RH which gives around 8 mc. Right ? So today I'm at 80F 60% RH = 11.7% mc So the idea is that I have to heat the cupboard till the temp and RH coincides with 8%mc. My gut feeling would be that the MC would stay the same - I guess I must be wrong ? |
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| Author: | Daniel M [ Wed Sep 20, 2006 3:14 am ] |
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Just winging it in an uncontrolled space can lead to some pretty nasty disappointments. Collapsing tops & backs are a common result if the humidity is too high during bracing & assembly of the box. Your tent idea is a good one if you can get the RH to acceptable levels. A heated storage cupboard will allow you to turn the dehum off when you are not in the shop for an extended period. |
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| Author: | Sam Price [ Wed Sep 20, 2006 3:21 am ] |
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A friend told me that he used to line his wood storage cupboard (A large metal office cabinet) with Volvo car door rubber seals...apparently that controlled RH extremely well, so famous are their doors for complete sealing. |
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| Author: | crazymanmichael [ Wed Sep 20, 2006 3:44 am ] |
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whilst rh is one thing to consider, another is the ambient dust, particularly that from the sculptor if he works in stone. what will your finishing options be? whilst i have never tried sharing a space i have read comments by those who have tried to the effort that it is a less than perfect relationship. |
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| Author: | Sprockett [ Wed Sep 20, 2006 4:24 am ] |
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Try this link: Humidor Humidifier All you need to add is a humidistat and they are cheap, in fact there are kits all ready to go, if you look this thing can do %70-%80 RH in 3000 Sq Feet so 47 in a shop should no be at an issue at all... It's a little pricey but not having to worry about it anymore to me is more than worth it. Humidor's and smoke shops are way ahead of us here 
-Paul- |
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| Author: | Tom Morici [ Wed Sep 20, 2006 11:25 am ] |
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Temperature has less to do with mc than the humidity, the chart shows that. Relative humidity is what you need to watch. The storage cabinet needs to vent too help drive off moisture. You need to raise the temp. for that to happen. There is room to play with on the moisture content of wood, it depends on where the instrument will live. On the coast RH is higher 10% is better, in a dry desert region Id feel safer with 6%. Hope this helps. Tom |
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| Author: | old man [ Wed Sep 20, 2006 1:18 pm ] |
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Thanks, Paul. Ron |
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| Author: | Wayne Clark [ Thu Sep 21, 2006 1:29 am ] |
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Tom, It sounds like you measure the moisture content of your wood directly rather than rely on the RH. Can you recommend a meter? |
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| Author: | Tom Morici [ Thu Sep 21, 2006 2:08 am ] |
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Wayne My meter is the mini Ligno by Lignomat I've had it for 12-15yrs. I don't know what is available now that would be a good value. I mostly watch the RH, but the meter confirms that my wood is dry. Tom |
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| Author: | Mike Mahar [ Thu Sep 21, 2006 2:19 am ] |
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That humidifier only seems to add water to the environment. It does not take water our. A cheapo humidifier can work quite will when it is too dry. The nasty problem is dehumidifying a space and that requires an expensive dehumidifier and good moisture barriers on the floor and walls. |
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| Author: | Sprockett [ Thu Sep 21, 2006 2:37 am ] |
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Mike I have not seen a combination unit ever, in fact even the humidistats are always either humidify or de-humidify but not both (some have both but you have to flip a switch for the mode). With that unit I don't have to keep filling something with water all the time, where if I forget the shop humidity drops below where I want it. For a dehumidifier I'm going to use my AC unit which has a 'dry' mode on it. Where we are it's pretty dry most of the year, in fact it's been raining and the shop has topped out at %48 which means my sealing job worked better than I hoped and it just doesn't get as humid here as other areas of the country. -Paul- |
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| Author: | Mike Mahar [ Thu Sep 21, 2006 6:44 am ] |
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Where I live it is either too dry or too humid. The humdidity is only at 45% for about two hours sometime in October. Just as it is transitioning from 75% to 28%. |
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| Author: | Billy T [ Thu Sep 21, 2006 5:42 pm ] |
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[quote]Controlling Relative Humidity[/quote] I got a cousin that lives in florida, I tell her to leave but she says she likes it there! 
Billy Dean Thomas |
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| Author: | Billy T [ Thu Sep 21, 2006 6:33 pm ] |
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[quote]I've been looking through the archives here and at the MIMF [/quote] The MIMF?? UNCLEEEEAN!! UNCLEEEEAN!!
Billy Dean |
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| Author: | Richard_N [ Mon Sep 25, 2006 9:13 pm ] |
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Thanks for the comments everyone. I've ordered my wood now. Once it arrives how long should I wait to let it stabilise before I start building ? Thanks |
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| Author: | Martin Turner [ Tue Sep 26, 2006 1:54 pm ] |
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Depends on where the wood has come from, how long supplier has had it stored, how well its packed etc etc. My wood gets stored in the workshop where I build at 40 -45% humidity and it doesnt get used for at least 6 months. Mind you I'm away working on oil rigs for half the year so waiting for the wood to stabilise isnt much of an issue for me. |
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| Author: | Kim [ Tue Sep 26, 2006 2:44 pm ] |
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[QUOTE=Billy T] [quote]Controlling Relative Humidity[/quote] I got a cousin that lives in florida, I tell her to leave but she says she likes it there!
Billy Dean Thomas[/QUOTE] |
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| Author: | Tom Morici [ Tue Sep 26, 2006 4:59 pm ] |
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I agree with martin, it would depend on the condition your wood is in when you recieve it. If you store your wood in a controlled conditions a few weeks "could" be enough. to be sure weigh your wood when you get it, a postal type scale should work. Weigh it once a week. When it stops losing weight. It should be stabilised. hope this helps. Tom |
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| Author: | Richard_N [ Tue Sep 26, 2006 6:53 pm ] |
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Great idea thanks Tom. |
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