An idea for drying slabs

They sell for between $2500-3000 here. I have a cabinetmaker friend that's buying a couple of them for just this; one for storage, the other for a kiln. I see them advertised on craigslist all the time; they must have a short life, or just have to be inspected/repaired to keep them roadworthy or something. I don't know the logistics of it. They apparently will deliver the containers on some sort of rollback, and don't need a crane to be unloaded. I think my friend was going to get a 30 footer, but I don't know for sure. Perhaps the 40 foot versions need a crane. I'm not sure. I'd love to put one up at the farm behind the barn, but getting it across the river(s) would be a little problematic. Don't think the driver would be too crazy about the idea.

Matildasmate said:

Hi Bob What's the average price for a container and did you need a crane to unload it , just wondering what it cost's roughly , to buy one delivered and unloaded . Cheer's MM

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Costs vary between states in Australia for some reason depending on supply and demand. A 20 ft medium quality used container in Perth costs AUS$2400 plus delivery.

Delivery costs/methods depends on the location. In my case the yard owner arranged that as his contribution to the deal. 20' containers weigh about a ton so if you use a crane it needs a long enough arm that can lift 1 ton up of the back of a truck - that's a bit bigger than your standard truck crane.

I got my container from a mate where it was cluttering up his space for slightly less than 1/3rd of the going cost. Admittedly it will need some rust converter and paint thrown at it but $100 plus time should cover that.

Cheap shed's

aquan8tor said:

They sell for between $2500-3000 here. I have a cabinetmaker friend that's buying a couple of them for just this; one for storage, the other for a kiln. I see them advertised on craigslist all the time; they must have a short life, or just have to be inspected/repaired to keep them roadworthy or something. I don't know the logistics of it. They apparently will deliver the containers on some sort of rollback, and don't need a crane to be unloaded. I think my friend was going to get a 30 footer, but I don't know for sure. Perhaps the 40 foot versions need a crane. I'm not sure. I'd love to put one up at the farm behind the barn, but getting it across the river(s) would be a little problematic. Don't think the driver would be too crazy about the idea.

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They would make cheap shed's , no stuffing around with the clown's (town council) . thank's Aquan8tor , look's like there similar price to to container's over here too , going by BobL's post , roughly , I think I will get a couple of 10'l x 5'w x 7'h gable end to end garden shed's , $300-400au each , when I am ready . Cheer's MM

anybody ever tried to dry a slab in a vaccum venner bag read some place it would work seems vaccum kilns are very fast dryers

Matildasmate said:

They would make cheap shed's , no stuffing around with the clown's (town council) . thank's Aquan8tor , look's like there similar price to to container's over here too , going by BobL's post , roughly , I think I will get a couple of 10'l x 5'w x 7'h gable end to end garden shed's , $300-400au each , when I am ready . Cheer's MM

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I would have gone with a shed if I did not need a bulding permit - especialy as I have the frame and the roofing materials for a 20' x 25' shed stacked up in my back yard.

What I like about containers is that they are self contained (I guess that's another reason why they call them a container ) with a built in ply and steel floor already about a foot off the ground. Because they seal reasonably well, controlling the air flow will also be easier.

Container's

BobL said:

I would have gone with a shed if I did not need a bulding permit - especialy as I have the frame and the roofing materials for a 20' x 25' shed stacked up in my back yard.

What I like about containers is that they are self contained (I guess that's another reason why they call them a container ) with a built in ply and steel floor already about a foot off the ground. Because they seal reasonably well, controlling the air flow will also be easier.

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A container is a great idea , very secure , especially where you have your's , by the sound's of it (apart from the vandal's with match's) , I reckon they would make cheap shed's also , no permit's required because it's not an erection , just a big box . One of the local blokes has recently had a shed erected for him , so far it has cost him over fifteen grand for a 40'L x 20'W x 10'H shed , concreted and wired . One thing , around here you don't need a permit to erect garden shed's . I got to thinking not long after my last post to this thread about garden shed's and thought hell why bother buying them either , just like you said in your last post about having the material's , I got enough second hand iron and it wont take me long to rip enough timber for a shed , I will line the inside with plastic , that way I can control the air flow and humidity , I can get cheap plastic also . Not sure where I am gunna get the time for all my project's though . Cheer's MM By the way good sense of humor Bob :hmm3grin2orange:

Finally decide to stack some slabs into the seatainer today so I took some pics.



It's only been in the yard 2 weeks and the graffiti munchkins have had had a go at it already. Outside looks pretty scummy but inside it's OK.



Here's a shot showing the ventilator holes.


The roof was bowed slightly upwards which was good for rain runoff but as soon as I cut the front hole the bow sprang the other way. I'm gonna have to jack up the roof and then get BIL to weld a piece of angle either side of the hole across the roof to maintain the bow in the right direction

When can you drop it off

When can you drop it off Bob , nice setup mate , nice stack of wood . It didn't take you long to get it all setup . Thank's for the pic's . Cheer's MM

Nice work Bob!

Now, lets see some pics of that container full!

Temperature data for the seatainer

Here is some interesting data about my seatainer. I bought some USB portable temperature/humidity sensors and put one inside the container on top of a pile of slabs (blue line), one in a metal box on the side of the container (yellow line) and one I left outside the container. The last one failed to trigger (still getting the hang of the software) but managed to get local daily min (red rectangles) and max (Black rectangles) temps for the last week from the weather bureau.



It looks like the temperature in the container is consistently about 5 - 10 oC above the outside temp. I was hoping for a bit more but maybe that a good thing. The weather here is quite cool at this time of the year and this weather pattern is more like what we see in spring and autumn. It will be interesting to see what happens when we hit 40oC

BTW those temp sensors are interesting little gizmos, 32000 data points of temperature and relative humidity, from one reading every second to one every 12 hours.

BobL said:

...BTW those temp sensors are interesting little gizmos, 32000 data points of temperature and relative humidity, from one reading every second to one every 12 hours.

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Now THAT is seriously interesting Bob. I agree, I would have thought the temps inside that container would be higher than that. Heck my upper (kindof an attic) portion of my shed is often 20 or more degrees hotter than outside on some days. Did you get those USB sensors locally or from a website I could also order from? I'd be interested in setting a couple RH meters into my piles of drying lumber if it wouldn't break the bank. You've got my curiosity, give us more details please!!!

woodshop said:

Now THAT is seriously interesting Bob. I agree, I would have thought the temps inside that container would be higher than that. Heck my upper (kindof an attic) portion of my shed is often 20 or more degrees hotter than outside on some days. Did you get those USB sensors locally or from a website I could also order from? I'd be interested in setting a couple RH meters into my piles of drying lumber if it wouldn't break the bank. You've got my curiosity, give us more details please!!!

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WS don't forget, 20F = 11oC, so it is about 20F hotter inside the container. Also, don't forget the container is ventilated with those wind driven whirlybird fans on the roof and vents on the sides.

The sensors I have are these http://www.electusdistribution.com....D=12&keywords=&SPECIAL=&form=CAT&SUBCATID=112
The $99 is an AUS retail price, I paid about US$55 for mine by buying through work.

There are heaps of these types of sensors on the net. Use "USB Temperatire/Humidity Datalogger" as a search term.

eg http://www.dataloggerstore.com/p4459/microlog_lite_16.php.

We use these sensors all the time at work when we transport polar ice and snow samples around. We throw one of these in the "eskies" (Oz term for ice cooler) and if the sensor come out wet we know the ice has melted! (just kidding). The transport companies guarantee the ice won't be taken above a certain temp and the sensor is our way of checking this.

Cheers

Thanks, going to check that out. We use temp sensors attached to the water depth dataloggers we drop down our observation wells, but the only humidity sensors are on our full blown weather stations and REAL pricey, I guess because they have to be so accurate. So, a small stand alone USB humidity sensor is what peaked my interest. Doesn't really have to be that accurate, as long as it senses changes in humidity from day to day. Would be interesting putting one or two in my piles of stickered lumber as it dries. I'm going to pursue that.

Yeah after I posted that I actually remembered you are part of the real world and you did say degrees C, and that changes the number spread significantly. We of course only use degrees C scale in all our equipment at the USGS, but as soon as I leave work I'm back in the Fahrenheit world.

thanks again

Good work Bob , I will have to look into some myself mate . Thank's for sharing mate . Cheer's MM

Here's the Relative Humidity (RH) data for inside and out alongside the inside Temp (T). Haven't got all the outside T unfortunately.




It's interesting to see the RH outside varies by around 50% during the day/night cycle but inside it varies by only 30%and doesn't go less than about 40% . I have read on the web that this rise in RH during the night helps the wood recover from the stress of drying out in the day.

Bob, the important thing to measure is the moisture in the wood. I can't remember the figure, but I think it should be no more than 1% to 2% less at the surface than it is 1 inch in from the surface. You can use test blocks cut from the logs if you need to.

The temperatures you have are a bit low, but not a problem (120 - 130 F is ok), and it may be because you have too much ventilation. The RH ought to be more than 90% so the wood doesn't have too large a gradient across it. When you get to those temps and RH, lots of things like to grow, so it's worth spraying the wood with a mixture of borax, boric acid and bleach. That stops fungus and beasties.

Drying wood in a kiln can take 3 months (or more) but the worst thing is to try and dry it fast.

Thanks for the info Roy - very helpful indeed

roy clarke said:

Bob, the important thing to measure is the moisture in the wood.

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Yep, have my moisture meter waiting to do this measurement after I have been going for a few weeks,

roy clarke said:

The temperatures you have are a bit low, but not a problem (120 - 130 F is ok), and it may be because you have too much ventilation. The RH ought to be more than 90% so the wood doesn't have too large a gradient across it. When you get to those temps and RH, lots of things like to grow, so it's worth spraying the wood with a mixture of borax, boric acid and bleach. That stops fungus and beasties.

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Yep I almost certainly have too much ventilation. Over the In the next few I will slow down the ventilation, and the outside temperature will also increase as summer kicks in. it will regularly get to 90-95F outside so I'm confident I can get them temp will get up around 130F without too much trouble. Do you have a specific recipe for the Borax/bleach mix?

roy clarke said:

Drying wood in a kiln can take 3 months (or more) but the worst thing is to try and dry it fast.

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That's why I thought I'd like to try and start slowly till I get the hang of it.

Thanks again.

I'll hunt around for the recipe, though I haven't seen it for 15 years.

The moisture gradient in the wood need to be measured every day to begin with, then less often as the moisture levels reduce and you are happy that things are progressing as planned.

Here some temperature data for January of this year (that's mid summer for us) for my drying shed (a vented seatainer) which as about 2/3rd full of timber slabs when these readings were made

Firstly a couple of explanations.

• The red line shows the air temperature in the middle of the inside of the shed.
• The blue line shows the outside temperature of the shed in the sun - its effectively the skin temperature of the seatainer (I place a temp sensor inside a steel box attached to the outside of the shed).
• the Orange line shows the daily max temp - you can see we had quite a few days above 90F, and 5 days above 100F
• The Green line shows the daily min temp. It never went below 50F and was generally above 60F overnight.

Some observations:
The highest temperatures are the skin temp of the shed which reached 55ºC (131F) on a day when it was 41ºC (106F) outside air temp.
The maximum air temp inside the shed is always greater than the daily maximum by ~7ºC (13F) but never more than the skin temperature.
The shed air temp never gets outrageously hot - The hottest it got to was just 46ºC (115F) when it was 41ºC (106F) outside. I could probably boost that by reducing the air extraction (two full sized whirly birds or self powered roof mounted fans)
The lowest temperatures of the skin are equal to or slightly more than the overnight minima,
The minimum air temp inside the seatainer is ~5ºC (9F) greater than outside air temp.
This is an excellent demonstration of how a shed full of timber acts as a buffer against low and high container temperatures.

What I should be showing you is the RH data - it drops to less than 20 during the day but shoots up like a rocket during the night to over 90% when the air temp drops because the timber is still toasty warm and as I said in my first post, this rise in RH during the night helps the wood recover from the stress of drying out in the day and reduces splitting. This would be not good for thin boards but seems to be fine for 2"+ slabs for most wood because there does not appear to be much splitting.

Great info.