Thread: Humidity Cabinet

pressing the top and bottom

carcase glue up

carcase

g o C f e Rob

That's definitely a sizable unit, looks good.

here is the next picture with a front added on to create the rebate for the seal .

How are you going to control the humidity in the cabinet Cab?

Well I have this unit, that removed 2.5 liters of water over night from my work shop , the humidity went from 77% down to 73 %
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So I thought if I enclose it in a sealed box it would hopefully drop from say 77 % down to 45% quickly and I may get, with a guess 150 ml of water in the container,

I finished the cabinet last Saturday and did the first test , thats when I took the picture of the hygrometer 11 am 12.1deg 72 % by 2 pm it read pretty much the same.

I thought it could be the placement of the sensor in the cabinet, so back at work this morning I moved it from eye height down to 150mm above the unit , 10 am it was about 70 % and by 3 pm it was down to 58% to 60% I kept it running till 8 pm and it stayed at 60%. so I think it has to do with circulation

I have another sensor coming from the US from Stewmac, and may have to go for the silica gel sugestion or heat it up more, any one know where to get silica gel in Melbourne?

Any one have any more sugestions ?

Biscuit joins for the doors,
Masonite pressed on one side,radiata pine shield panels for the fronts.

Gave it one spray coat of acrylic pale yellow then tried milk paint for the first time

The seals work well

Milk, hydrated lime and paint tint ,one green the other yellow .it dries and looks just like the antique paint jobs, needs a bit of ageing.

Got to get the humidty thing sorted,if it does not work out the cabinet has other uses

Bent my first blackwood side tonight on my bending iron, was a bit nervous about mucking it up,but it came out ok for a first try, a bit of charring to remove .

Originally Posted by auscab

I finished the cabinet last Saturday and did the first test , thats when I took the picture of the hygrometer 11 am 12.1deg 72 % by 2 pm it read pretty much the same.

12.1degC???? Thats pretty cold.

What I woud try is fitting a couple of 100watt light bulbs inside your cabinet. Leave them on and see how humidity changes over a few hours with just the light bulbs on...you'll be surprised.

BTW that cabinet looks like a work of art.....looking forward to some stunning looking guitars at this rate!!

Cheers Martin

I want to get is a simple thermometer to put inside,and I am looking at the light globes soloution and the silica,but was hoping to get humidity down and then turn off any electricals .

ha ha work of art ,thanks ,I copied the style from a Barossa valley food cupboard which holds my power tools,and got it done quick with the help of two apprentice cabinet makers.

you can try beer brewing heaters. Mine is adjustable from 18 to 45 deg, the thermostat has a leeway of 2 deg before it cuts in or out. Think ill go have a beer.

I went to Bunnings and got two $5.00 themometers and a $17.00 hygrometer ,I got a hygrometer from Stewmac,tested the three and the Stewmac and the bunnings gave similar readings so these went into the cabinet access door.

At bunnings they have groups of different style thermometers, I compared the readings and some of them gave big differences in temperature out of the same box, the alchohol ones in the picture gave the closest readings

I also had delivered from a guy called Leon who runs a small business in QLD, silica gel, 2 kg of beads with blue beads in the mix that goes pink when they reach saturation,you can then heat them in an oven to dry out and re use,also a paper indicator and some clay desiccant , which absorbs quickly but is supposed to be a throw away, dont see why that could not be dryed out as well,but I didn't ask him that.
Leon is into his gell , his acoustic guitars and likes a chat, and answered all my questions,so if any one wants his details I will add it , just ask and I will add it,or is that breakig rules?

I put the clay and the1 kilo of the gel in a cheescloth bag inside and got a 10% drop over night. BONZA
With the small door being opened to pull parts out a few times a day and to check readings i'm getting arroun 48 to 50 % with out of the cabinet readings at 60 to 73 % .

If I want more I will have to add lights or heater but dont want to have electricity running over night and I assume if humidity goes down while lights are on it rises when lights are off ?

The cabinet is placed to the right side of a guy's bench, all week we have been saying how " bright and cheefull " it looks,especialy compared to the rest of the work shop.
When a former employee walked in we were joking about it's bright nature ,we had a laugh about it.and I said thats why we put it at the end of his bench, ha ha

next day the guy who's bench it's next to cracks it at me ,for haveing it next to his bench I didn't think he cared that much!

So he got the job of ageing it up a bit,
first thing he offers is to head but the top right panel, No No ! I gave him a block of wood with stones glued to it and he biffed off bits.
We added colours and wiped them off, then I pulled out a rarely used, it's a rubber squee gee sort of thing ,you wipe it across the surface with a floating water colour, and it leaves a wood grain pattern, He did the sides and the panels only ,not the door frames, that finished it and we are all a bit happier with it

one of the pictures is my first build in the cabinet so far.

cheers Rob

Hi Rob,
I really like the look of the cabinet and the very economical way you made it (both time and materials). Can you explain the purpose of a humidity cabinet? Is it to maintain the moisture content of seasoned timber (and projects while you are working on them) so all the components have a similar moisture content? Or is it to dry timber?

If you warm the cabinet with some incandescant lights (if you can still get them) the relative humidity will drop since the air temperature has risen, but if you sealed the cabinet perfectly and the paint is impermeable there will still be the same amount of moisture in the cabinet and soon after you turn them off and the temperature drops, the relative humidity will rise again. Additionally, if the wood has a moisture content high enough that it releases water to the air when the lights are on, then the relative humidity will go even higher when the lights are off, unless you remove that water (you might even get condensation).
The seals won't be perfect and the paint won't be impermeable, but I would have been interesting to see if leaving the inside unfinished would have helped buffer the humidity better.
So yes, lights will help but you still need to use a desiccant or that dehumidifier to remove the water.
Silica gel will absorb almost 40% of its weight in water but the cobalt chloride will turn from blue to pink with only an 8% weight change. So it is a good indication of dryness, not so much wetness. Better to weigh out an amount into a glass container, then reweigh it at a later date and regenerate when its >30% increased in weight. You can get acceptable digital scales for less than $15 from Woolies if you don't have any.

I'd also like to know more about your milk paint recipe. I have one but would like to know more.

Cheers
Michael

Sides in the mold are looking good.

Was it really so bad having a nice bright item in the workshop?

Looking good Rob,

I wouldn't bother about storing the sides in the cabinet if they're in the mould. The vulnerable parts of the guitar are unbraced tops and some backs.

Cheers Martin

Originally Posted by mic-d

Hi Rob,
I really like the look of the cabinet and the very economical way you made it (both time and materials). Can you explain the purpose of a humidity cabinet? Is it to maintain the moisture content of seasoned timber (and projects while you are working on them) so all the components have a similar moisture content? Or is it to dry timber?

Michael,

The humidity cabinet's prime function is maintaining the components of an acoustic guitar in a controlled environment humidity wise. Like any cabinet work (this is what luthiery essentially is) changes in humidity will result in changes in wood moisture content and dimensions/volume of same. Ideally one should build in an environment that is slightly drier than the environment the finished guitar will end up....better to have the wood swelling a bit rather than shrinking (=cracks). My workshop is humidity controlled and I keep Rel Humidity at around 40%. Final thicknessed tops that havent been braced are particularly vulnerable to ending up looking like a Smiths crisp if left in an environment where humidity is changing significantly.

Cheers Martin