Thread: Dry the Log out First?

Good question ,I'd like 2 know also and will be watching this thread with interest -thanks

Originally Posted by Matthewd

G'day all. Question:
Is it better to let a log dry first before milling it with the a slabber or cut it green? what would be the advantages and disadvantages?
What is the difference in the drying process of a Pinus radiata(softwood ) compared to something like a Eucalypt (Hardwood)

It's generally much easier to mill green since the wood is softer and all the benefits that accompanies this, quicker cutting, less sharpening etc.

Wood also dries faster if it is cut up when green but the disadvantage is the wood can warp and crack more while it dries.

With some trees it is best to let them dry out a bit first. For example lemon scented gum moves least and is still not rock hard if it is milled just after the bark falls off.

The process of air drying softwood is the same as hardwood. I'm not sure about kiln drying but my guess is it varies depending on the species.

I had a couple of stringy barks here which we felled when we built the house and I left them down the back with a plan to slab them one day soon. That turned into 2 years. A log is never going to dry out in that time but what does happen is twofold: Firstly, you are going to get internal collapse as the heartwood shrinks away from the centre. This will open up great big cracks that run the length of the log and renders a lot of it useless. The second is that you will find it very much harder to cut than when it is green (I assume we're talking chainsaw slabber here?).

I'd recommend slabbing it as soon as possible, unless there are special circumstances for the tree type as suggested by Bob.

As far as possible you should mill green near to finished size ( with allowance for some cup, warp, shrinkage etc and further dressing) Reason: If you mill a slab 300mm wide and down the track you want to split it to 150mm it will bow as the outside will be drier than the newly cut side.
If you leave the log whole it will crack radially - most shrinkage is along the growth rings.
Green logs are softer although heavy to move and gum saw blades more rapidly.
Smaller sections will season in less time - rule of thumb is 1" = 1 year unless you have a kiln.
Always seal the end grain - old paint, mobil cer M or anything which will seal the end. Make sure to use spacers (stickers) evenly placed to allow air on all faces, vertically aligned.
Difference between timbers will be the amount of shrinkage and hence the likelihood of warping.
Most gums are difficult to keep straight and denser timbers tend to take longer. If a timber is known to be relatively stable (less prone to warping) it will be better suited for large slabs. Sorry for long winded response - big question.

Have you ever tried to mill bone dry ironbark, I had to one day. You don't get shavings, you get a fine powder and a blunt saw.

Milling green is much easier, especially if you're slabbing (for example) an 800mm wide, 5m long Blue Gum. The chain had to be sharpened at least twice a slab, and that's green.
Also, waiting for a log to dry is ridiculous

champs, that wasn't long winded by all means . The short of it is most milling should be done when logs are green (wet) end sealed,stacked properly and stored correctly.There's a wealth of information in the forum relating to almost every timber you will find in oz and how to dry it or cut it. like bobl said sugar gum can wait a while. personally i've found soft woods can sit in the yard for quite a while without splitting but will develope blue stain if kept in the round for too long. any way it might be best to be log specific. and ask questions about one type of log and not generalise too much. ie; i can tell you alot about blackwood or macrocarpa pine but not some of the northern timbers you might be milling

I agree mill it green - it reduces the drying time and also as most wood cracks from the heart/pith the slabs with no pith have a better chance of drying with minimal checking.

The slab with the heart may crack but in most cases that will only require splitting it down the middle when dry to eliminate the checking - so in short i think you get less wastage/bad slabs if slabbed green and allowed to dry.

Hope that helps

I have founder waiting at least 6 months to a year before I will sink the Lucas into eucalypt, find I get a less stressed log that tends to stay straigter, other species blackwood, pine and the like, I can mill staight away, does'nt seem to matter

Best milled green.

However, it has been found that trees covered by water in flooded dams or those logs salvaged from the bottom of rivers, although they have not dried out they have become stable.

Dont know how long you would need to leave the log submerged and im sure the greenies would love you as the tannins in the log leach out but if you have logs that are going to wait a while before milling it would be worth trying.

There's a method called water seasoning where the green log is submerged for a couple of weeks before drying normally. Apparently it results in less movement but it makes the wood brittle and no good for any application where strength is required.

Slicing 'em up green is the go Matt for all the above reasons and more - you will find you're log has rotted before it dries out in log form, or you have become too old to push a mill...

yep the rule of thumb for air drying is 1" of board thickness for 1 year of air drying, although this increases once the board is 4" thick or more.

If you apply this to a 20" (600mm) log you're looking at well over 20 years to 'dry' as slabs you might look at only 2-3 years...

Also softwoods get blue stain, which most people don't like = useless timber

best to slice green

Lastly Champs, welcome to the forum - although you're reason behind why a 300mm slab ripped into two 150mm pieces which bend isn't quite right. Sure the newly cut face is greener than the outside edge of the board, but it doesn't pull due to that it pulls to the sap and due to the orientation of rings in the resultant boards.

As an example, I can cut a green log, all faces of the board are green - nothing is 'drier' than another part and I can still cut it to pull, I can also cut a log which has been down for 5-6 years so the outer few inches of the log are much drier than the internal timber and from this log I can cut a board which doesn't pull - so hence why I'm saying it's got nothing to do with 'part' of the slab being drier than the new cut.

G;day.Thanks very informative.

Pull due to sap is an interesting sounding phenomenon - not sure what you meant by it. Timber can close behind a cut meaning the inside is pulling or open behind a cut meaning the outside is pulling.
Radial or tangential cutting definitely has an impact on this tendency. This difference in tension can have a number of reasons one of which is differential drying. Equilibrium moisture content is achieved when the whole section of timber is similar to the environment it is seasoned in. As humidity changes through the year particularly in coastal regions, there is always going to be a lag between inside and outside - it can in fact have a higher moisture content towards the outside at a given time of year.
The way the tree was leaning on a hill can also have an impact on this tendency to pull. The main point of the advice is that you are going to minimise the pull you get later if you saw close to size at the start.

An interesting phenomenon? that sounds like you you think it's hocus-pocus or voodoo??

It's an easy learnt tendency, when milling for even a very short time???