Oak, milled and straight into the kiln?

[Chipperclown]

Question please. Can I have milled a large oak truck milled into slabs or small chunks and have this kiln dried for quick use straight away. I have always air dried before for home  projects thinking this can not be done, however I am seeing otherwise online?

[ucoulddoit]

Was hoping someone would answer this question as I’d also be interested.  So in the meantime I’ll speculate / guess, and maybe someone who has a kiln will set me right. I suspect there isn’t a definitive single answer and type of kiln and future use of the timbers needs to be considered.

 

Oak is particularly susceptible to surface checking right at the start of drying, so I’m guessing a steam kiln might be better than a dehumidifier kiln for green oak? Other drying defects such as case hardening and honeycombing due to drying too quickly are caused when the moisture content variation from the outside to the centre of timbers is too large. So the drying schedule needs to be regulated to control this variation which depends on timber species and thickness. So filling a kiln with a mix of species and / or timber sizes doesn’t work efficiently as the schedule needs to suit the ‘slowest’?

 

I’ve no experience of using kilns. But that hasn’t stopped me milling and drying timbers for my own use for many years, mainly furniture making for centrally heated houses and have never had any problems. But it does take quite a long time, so I understand why this question was asked. I always air dry planks using the rule of a year per inch thickness, plus a year. Then I bring timbers into the workshop which I keep dry with a small domestic dehumidifier. After at least 6 months they are usually down to 10% moisture content or less and ready for use. 
 

From what I’ve read over the years, I gather that timbers dried slowly in the ‘traditional’ way are better to work with for furniture making. But I guess that with timbers for other types of project, the drying method and speed might be less of an issue? Flooring for instance?

 

Andrew

Edited February 4, 2023 by ucoulddoit

[Squaredy]

1 hour ago, ucoulddoit said:

Was hoping someone would answer this question as I’d also be interested.  So in the meantime I’ll speculate / guess, and maybe someone who has a kiln will set me right. I suspect there isn’t a definitive single answer and type of kiln and future use of the timbers needs to be considered.

 

Oak is particularly susceptible to surface checking right at the start of drying, so I’m guessing a steam kiln might be better than a dehumidifier kiln for green oak? Other drying defects such as case hardening and honeycombing due to drying too quickly are caused when the moisture content variation from the outside to the centre of timbers is too large. So the drying schedule needs to be regulated to control this variation which depends on timber species and thickness. So filling a kiln with a mix of species and / or timber sizes doesn’t work efficiently as the schedule needs to suit the ‘slowest’?

 

I’ve no experience of using kilns. But that hasn’t stopped me milling and drying timbers for my own use for many years, mainly furniture making for centrally heated houses and have never had any problems. But it does take quite a long time, so I understand why this question was asked. I always air dry planks using the rule of a year per inch thickness, plus a year. Then I bring timbers into the workshop which I keep dry with a small domestic dehumidifier. After at least 6 months they are usually down to 10% moisture content or less and ready for use. 
 

From what I’ve read over the years, I gather that timbers dried slowly in the ‘traditional’ way are better to work with for furniture making. But I guess that with timbers for other types of project, the drying method and speed might be less of an issue? Flooring for instance?

 

Andrew

I no longer use my kiln as it is simply too big and expensive.  But I have used it many times over the years to dry all sorts of species.  Larch I have successfully dried from green - but it took about 6 weeks and cost an arm and a leg.  Oak at say one inch thick I would estimate would take three or four months from green, and even then you might find it is ruined by internal honeycombing.  And I suspect the cost would be greater than the timber is worth. 

 

I have kilned air dried oak an inch thick and this took a week or so - no problem at all.

 

Unless it is very thin oak I wouldn't bother.

 

Other species may respond much better - ash, poplar maybe and softwoods, but not oak.

[wills-mill]

I'd always lean towards always air drying beforehand, I think. Oak just behaves like such a knob if rushed through the drying process.

One other major factor to watch is the quantities of tannin and goo that get dragged out of Green Oak by a kiln will do absolutely horrendous things to standard dehumidifier or heat coils, and any other metal fittings.

It's certainly mentioned in the textbooks, and I have been told of one *very* expensive incident locally (back in the good old days) when somebody thought it was a wizzo idea to run a load of Green Oak through a brand new kiln.