The November meeting kicked off to a slow start because we had a few technical difficulties that initially prevented Hiski from talking about the Mechano-Sorptive effect of wood.

Fire Safety

Roger didn't require any technology for his presentation so he stepped in to the breach and talked with us about fire safety in the workshop while the technical team sorted out the issues preventing Hiski's presentation being displayed. Roger is an former fire fighter and has maintained fire fighting equipment for his fire brigade so he knows a thing or two about fire.

He started off by going over some of the things he covered in his presentation earlier in the year because many of those present tonight had not been present previously. Yours truly was glad he did because I have a better understanding of the risks as a result.

Roger described how fire extinguishers work and how to use them before going into more detail about the fire triangle. The triangle is used to classify things that could initiate of be involved in a fire - fuel, oxygen, and catalyst. These things contribute to the fire risk and subsequent chain reaction of events should a fire break out.

Roger then lead the group is a discussion about the different types of fire hazards and how that can be mitigated. We were all pretty familiar with the flammable materials such as finishes and petrol, but some were not so aware of the danger of power tool batteries. The discussion went on for some time and it was great to have involvement from many of the group as we alll had different perspectives on how to deal with the risk of fire.

The Mechano-Sorptive effect of wood

Hiski Kippo told us all about the Mechano-Sorptive effect of wood following our break. We're all familiar with the expansion and contraction of wood due to the changes in the moisture content of the wood. The Mechano-Sorptive effect is similar but also different to that.

Hiski explained that the Mechano-Sorptive effect is the relaxation of stress in timber caused my changes in moisture content over time. He used the example of Indigenous people making a spear from a bent piece of wood by drying it and then bending it straight over a fire until it straightens out due to the stress in the wood being released.

He explained another example of the phenomenon using a photo of a stand of birch trees in Scandanavia which showed a lot of straight trees and one that had been bent over like an arch. The weight of snow on the leaves at the top of the tree had caused it to bend over during the winter. Apparently in winter the sap from the birch tree flows down into its roots, essentially drying the timber, and when the sap returns to the tree in summer the tree remains bent permanently. This is the Mechano-Sorptive effect in action.

Hiski's presentation was so fascinating that yours truly was so engrossed in it that I forgot to take photos of the presentation.