Box for humidity control

ozziebluesman · Post by **ozziebluesman** » Sun Oct 12, 2008 12:26 am

Hello everyone,

I'm about to start another guitar building project but before i do, i want to get a my humidity control box operating efficiently. I have been using absorbing gel packs in the box but this form of humidity control is not reliable enough especially when levels are high!

Humidity levels here in Townsville vary considerabily from now till April next year so I need to get this process right.

The mdf board box is sealed with varnish on the outside and has a hinged lid! The box measurements are 1mtr long, 70cm wide by 50cm high.

Through research on the MIMF forum i understand the box needs a light globe installed inside the box in a ceramic light fitting to reduce fire risk. Also a computer fan is fitted to remove the hot air from inside the box and a dim switch so you can controll the wattage, heat output of the globe. Some even insulate the inside of the box.

So some questions are were is the best position for the globe and the fan? Do you insulate the inside of the box?

I have a hydrometer to monitor the levels in the box.

I would be really interested if anyone else on the forum uses this form of humidity control and if they could help me with some advice!

Any other ideas, suggestions, greatly received.

Cheers

Alan

Lillian · Post by **Lillian** » Sun Oct 12, 2008 3:22 am

Alan, I must caveat this of course, no I haven't built one. I was going to until Ryan decided to move to Denver to be corrupted by his brother, (well someone has to teach him good scotch from bad and my drinking days are behind me), and I took over his room. My plan was to mount the globes on the bottom and put a wire mesh across the bottom over them as insurance against me being clumsy and dropping something on them and mount the fans on top of the sides. Didn't want to put them on the top because I knew I would drop something in them. I was also going to use rigid insulation with foil backing on the inside with hard board over it. I felt that it would be less likely to be abused on the inside. But as long as you cover it, I can' t see that it will matter if its inside or outside.

Just my two cents.

Allen · Post by **Allen** » Sun Oct 12, 2008 7:24 am

The fan is a heck of a good idea. Is it set up to vent air, or just move it around inside the box?

100 watt bulbs get plenty hot, so I'd want it somewhere far enough away from your stash, so you wouldn't stand the risk of scorching it. But that's pretty obvious anyway.

What is the point of the insulation? Is it to help keep the heat in, or to prevent potential scorching and risk of fire to the inside of the box from the heat of the bulb?

ozziebluesman · Post by **ozziebluesman** » Sun Oct 12, 2008 9:08 am

Hi Lillian. Yeah the insulation i thought on the inside would be best and protection over the globe is a good idea. Thanks for your input.

Allen i think the insulation is to keep the inside of the box hot and then you don't have to use a high wattage globe! Something like 25watt. The dimmer allows you to dial the wattage to the globe down so you can get the right amount of heat in the box to achieve the humidity levels you want! Unfortunately, i haven't been able to find good information regard a good system yet so i thought this is a good question for the form. Thanks for your input mate!

Cheers

Alan

ozziebluesman · Post by **ozziebluesman** » Sun Oct 12, 2008 9:55 am

Allen said "Is it set up to vent air, or just move it around inside the box?

Good question mate. Not sure what would be best.

I was thinking maybe a computer fan at the bottom of the box to suck air in and another fan at the top of the box to suck the moist air out!

Cheers

Alan

Kim · Post by **Kim** » Sun Oct 12, 2008 10:10 am

Have not made one myself but what I do recall is that you have a vent in the top and the 45W bulb in the bottom, circulation occurs as the hot air rises.

Cheers

Kim

graham mcdonald · Post by **graham mcdonald** » Sun Oct 12, 2008 10:13 am

I made one similar a few years ago to offset a cold and damp Canberra winter. They don't really control humidity, but by raising the temperature the RH is lowered. I found a 40-60W bulb was all that was necessary to bring the humidity down to a reasonable level. I didn't worry about a fan, just drilled a couple of 1" holes in the top to let the hot air out.

A far better solution, is to build a cupboard with a de-humidifier. I built one in Sydney many years ago in the corner of my workshop that was twice the size of my go-bar table, ie just enough room in front of the go-bar deck to use it, with a small de-humidifier underneath. The cupboard from just 2x4 framing and some cheap sheeting that was fairly airtight (and a door!) It didn't cost much and did mean a controlled environment for both storing and gluing.

cheers

graham

Craig · Post by **Craig** » Sun Oct 12, 2008 11:36 am

Some sympathy here folks . From what I've been told , poor Martin has had to go to the extent of buying out a complete aircraft hanger to house his stash

Dominic · Post by **Dominic** » Sun Oct 12, 2008 12:36 pm

I think you could be right Craig. The way Martin (Rockefeller) has so quickly cornered the global market in tone wood is nothing short of brilliant.

However, I heard the ACCC is planning to step in and split up his empire into top wood and B&S subsidiaries in order to restore competition to the industry.
Dom

ozziebluesman · Post by **ozziebluesman** » Sun Oct 12, 2008 2:36 pm

Thanks Kim and Graham for your input!

Yeah well we all know about Martin's stash. I think he is smart man as good tonewood is only going to get more expensive and harder to source in the years ahead. His stash will probably out perform his super fund.

I actually only want the humidity box to house my works in progress. I made the box big enough to house a guitar in it's mould.

My stash is very small but it's slowly growing!

Cheers

Alan

Allen · Post by **Allen** » Sun Oct 12, 2008 3:20 pm

If you go the fan route to vent, you 'll only need one. Nature abhors a vacuum, so if you're sucking air out, you'll need a vent to let some in.

When we were traveling this beautiful country in a caravan, I had to install one of those computer fans in the fridge cabinet. When it was running on gas and the temperature outside was over 30, the heat would build up so high that the fridge couldn't stay cold. With the fan just venting air to the outside, the temperature inside the cabinet dropped by 10 degrees, and you could feel a slight draft getting sucked in the fresh air intakes.

ozziebluesman · Post by **ozziebluesman** » Sun Oct 12, 2008 3:38 pm

Thanks Allen! I was also thinking that the vent on the bottom of the box could be adjustable to control the amount of air being sucked into the box. Thats only my theory. Do you think that would be a useful control Allen?

Cheers

Alan

Allen · Post by **Allen** » Sun Oct 12, 2008 6:54 pm

I suppose it wouldn't hurt. It's a pretty simple thing to build. And you might find that it's worth it's weight in gold.

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Box for humidity control

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