Timber Moisture Content/Hardness

[CHJ]

Reading @Mike G's Thread on the Superb Workmanship in Oak and the comments about moisture content brought to mind several instances I've come across over the years that caused me some surprises.

One instance being some Local Hedgerow Elm that I have air dried over recent years for turning, fully expecting it to be hard and tough to handle found that it was no harder, maybe less hard than some local Beech similarly dried, both in the 10-12% region on my simple meter.

Yet, and this is getting to the point of my pondering; back in the late 1940's early 50's we had loads of Elm board off-cuts to use as 'make-do and mend' on the farm sourced from a local village coffin maker that were so hard you could not knock a straight nail through them without drilling a hole first and too tough for me as a nipper to saw by hand. I wonder if it was just 'cooked' as he was probably the guy who recovered several very tall Elms we had blown down in a storm.

Another aside: needless to say there were quite a few gates, styles, shed doors, chicken pens etc, with fancy triangular repair patches from coffin lid offcuts to be seen.

 

[Doug]

I think the brittleness Mike is suffering is purely down to over kilning, I made my olive ash dining table from air dried olive ash that registered a 0.0 reading on my moisture meter but the timber itself worked well with both hand tools & machines & showed no signs of brittleness.
Given the choice I much prefer to work with air dried timber & have seasoned a lot of it myself over the years, I’ve some very large planks of elm I got quite a few years ago it will be interesting to see how hard it is when I get round to digging it out of the woodshed.

 

[HOJ]

I had this Kiln dried Oak dropped a week or so ago, and when cut and planed and taking random sample measurements its showing a fairly stable 10 - 11% on my meter, and working nicely:



Not neccessarily directly related, but I've been experimenting with some Holly, I knew it can be a pain to dry, but never experienced how it reacts to just air drying, anyway I'll post some pictures of progress so far:

In this one I had just re sawn it to a block, moisture was reading 25% and looks really nice and white:



And after a month, just sitting in the workshop, reading was down to 21%, a few shakes had developed, but interestingly the bit I chopped of the end was completly distorted:



I did check on it yesterday, and its now completly split on all faces, almost as if its tearing itself apart, didnt take any pics of it at the time.

 

[CHJ]

Only way I've managed to dry it without excessive splitting is to cover it thoroughly in wax and forget it for a decade.

Small turned items when green and 'dried out' during turning and finishing kept their shape and colour.

The other annoying problem with it is the green/black discoloration.
A google on the problem came up with:-

Causes of Discoloration

• Fungal Staining (Blue Stain): The primary cause of gray, blue, or green discoloration is a fungus that grows on the sapwood very quickly after the tree is cut. The fungus is prevalent in the environment and thrives in warm, humid conditions.
• Chemical Staining/Oxidation: The wood also contains enzymes that can cause slight graying or yellowing, especially if exposed to direct sunlight or certain finishes.
• Harvest Time: Cutting holly when the sap is flowing (not in winter) significantly increases the likelihood of the sap fermenting and causing discoloration.

Prevention and Treatment
To achieve the desired pure white color, specific measures must be taken immediately:

Prevention (During Drying)

• Harvest in Winter: Fell the tree during the coldest part of winter when fungal activity is low and the sap is down.
• Speed is Essential: Mill and begin the drying process as soon as possible after felling. Any delay can lead to immediate staining.
• Kiln Drying: This is the most effective method for preserving the white color.
• Air Drying Precautions:
  • Debark Immediately: Remove the bark promptly after cutting.
  • Ensure Good Airflow: Use thin, light-colored stickers between boards to promote maximum airflow and prevent staining from the stickers themselves.
  • Control Humidity: Use fans or a dehumidifier to speed up drying when air drying at home.
  • Keep it Clean: Prevent the wood from coming into contact with dirt, dust, or other sources of fungal spores.
  • Avoid Sunlight: Keep freshly cut lumber out of direct sunlight, which can promote yellowing.
  • Chemical Treatment: Some woodworkers have found success by soaking freshly turned "green" pieces in alcohol for at least a day to help inhibit fungal growth.

 

[HOJ]

Grabbed a couple of snaps of the Holly as of today, surface meter reading was @ 15%:



I had hoped to make a chess board with it, for the clients 60th bithday present, who's tree it's from, but I still have 2 years to go before it needs to be delivered, so an alternative option will need to be found.

 

[Doug]

Holly is a bugger to season in my experience @HOJ the only success I’ve had with it is if it’s quarter sawn, lovely timber mind so worth the extra effort.

 

[HOJ]

@Doug, did you re saw them from the log? I still have 2 bigger bits out in the yard, with the skins on, debating wether to slab them or not.

 

[duke]

Grabbed a couple of snaps of the Holly as of today, surface meter reading was @ 15%:

View attachment 37280View attachment 37281

I had hoped to make a chess board with it, for the clients 60th bithday present, who's tree it's from, but I still have 2 years to go before it needs to be delivered, so an alternative option will need to be found.

Wow, that is a lot of movement. Tell me if I'm wrong but does Holly get used much with furniture making other than inlays?

 

[Doug]

@Doug, did you re saw them from the log? I still have 2 bigger bits out in the yard, with the skins on, debating wether to slab them or not.

Yes sawn from the log though as it was a big Holly I got a friend at the local saw mill to do the cutting up