Sterilization box

[Buck69]

I am building a hot box to sterilize hardwood and set pitch in pine and ERC if the cedar needs it.
It will be 4'×2'x12'.
I searched the site for posts on building it and found a bunch of great info shared by the members here.
I have a ink bird controller and a small fan rated for a little over 200 deg.F. I believe the fan is rated for 125 cfm ( not sure if it will be big enough).
What I didn't find in my search or maybe missed is do I need to sticker the lumber or can I just flat stack it.

   Thanks for any advice in advance. 

[Ianab]

I think that because you are only trying to sterilise, as opposed to dry, a smaller fan will be OK. When drying you need to have "x" airflow to carry the moisture away, In your case, you just want the whole box and it's contents to reach ~170F and stay there for a while. The fan is to keep the air moving somewhat and prevent hot and cold spots. Without any fan the top will get a lot hotter then the bottom, you just need enough airflow to prevent that. 

[doc henderson]

I think you need it stickered or the center of the stack (beam equivalent) may not reach temp.  the overnight at 160°  so the core hits 133° is for 1 inch boards.  the stickers make a bunch of 1 inch boards, and not a 12 x 24 inch beam.  for drying, the fan whisks away surface moisture.  in your box it just makes sure the heat is evenly distributed around the boards.  heat will move in a gradient fashion, so a cool spot will pull more heat if it comes in contact with it.

[Buck69]

Thank you lanab and Doc Henderson for the replies.
The fan came today and I plugged it in for a quick test and believe it will be sufficient for circulation.

I'm glad I ask about the stickers because I was thinking of flat stacking but Doc makes perfect sense to use them . 

I read something from this forum several times a day for the last couple of years and I'm still amazed at how many people on here want people to succeed and offer there advice unselfishly!!

[Ianab]

Without stickers you would get the wood up to temp, eventually. But it might take days rather than hours. 

Think of it like cooking bacon vs a whole ham.  ;D

[LeeB]

Food already?  :D :D :D :D :D :D

[Buck69]

I liked the pork analogy, but was thinking the same thing Lee,maybe this is a new record for how fast a thread diverted to food although it usually involves grits  :D

[K-Guy]

maybe this is a new record for how fast a thread diverted to food although it usually involves grits

They don't eat grits in New Zealand, maybe polenta? smiley_jester

[Crusarius]

I would love to see a documented build. I have been wanting to build one also.

[doc henderson]

It will be a small box, and to heat but not dry you need 100% humidity.  that is good.  If you were heating a dead stack of boards at less than that, you would get some warp and cup, as you pull moisture from only one side of the top board.  stickered you can pull from both sides while heating.

[Buck69]

 I will take pics and post how I build it and also do a follow up on how it works. 
It's not going to be anything special kind of quick and dirty. 
I have a pile of ewp on sticks  I cut last spring on the neighbor's Norwood manual sawmill. 
I live about 15 miles south from a greenhouse and maybe 20 miles north of another. 
I'm trying to make some raised planters like Bruno's and see I they sell before it gets to late in the planting season. 
Dad always said I was a day late and a dollar short.

[Buck69]

Just a idea, if I were to cnc router something on them what would you guys and gals think would be something not to specific (like a ball team or college  name)that would appeal to most people.
I was thinking something with flowers and maybe a hummingbird?

[samandothers]

I was thinking something with flowers and maybe a hummingbird?

Or flowers and bees.

[Crusarius]

Put mud dobber holes down the side. Give the pollinators a house and food

[scsmith42]

Christian Becksvoort had an article in Fine Woodworking Magazine about a home built sterilization chamber that used saw horses, foam board and a space heater. Boards were stickered on edge on top of the sawhorses with the foam board box dropped over them. The space heater was under. No fans. I have a copy of the article if interested.

[Ianab]

Christian Becksvoort had an article in Fine Woodworking Magazine about a home built sterilization chamber that used saw horses, foam board and a space heater. Boards were stickered on edge on top of the sawhorses with the foam board box dropped over them. The space heater was under. No fans. I have a copy of the article if interested.

Should work because all the boards are in the top of the box. Warmth from the heater would rise up into them and circulate with convection. It would work "good enough" without fans in that configuration. 

[Crusarius]

That sounds really interesting. Could be a fun experiment

[melezefarmer]

If the intention was to sell lumber for outdoor use, could you just stick the fresh sawn lumber in a sterilization box with the heat cranked up to 170f? Once the lumber reached the appropriate core temp to set the pitch and sterilize, you immediately remove the lumber to air dry?  As an added bonus, one could heat the box with a wood stove in order to save on electricity without affecting the lumber quality.

[LeeB]

Once the lumber reached the appropriate core temp to set the pitch and sterilize, you immediately remove the lumber to air dry?

Better to air dry first and then heat treat. Bugs might move back in the other way around.

[melezefarmer]

If I were to air dry first then sterilize using a wood stove for 24hrs, would it impact the quality of the lumber? I'm mainly looking into producing cedar decking.