Seasoning - Revision history

DT Online at 12:50, 7 January 2018

2018-01-07T12:50:35Z

← Older revision		Revision as of 12:50, 7 January 2018
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	=====Introduction=====		=====Introduction=====

	Over half the weight of a growing tree is water or [https://en.wikipedia.org/wiki/Sap '''Sap''']. ~~Freshy~~ [https://en.wikipedia.org/wiki/Felling '''Felled'''] or [https://en.wikipedia.org/wiki/Green_wood '''''Green'''''] timber with such a high [https://en.wikipedia.org/wiki/Water_content '''Moisture Content (MC)'''] is susceptible to attack by [https://en.wikipedia.org/wiki/Wood-decay_fungus '''Fungi'''] and may crack, warp and twist if dried out too quickly.		Over half the weight of a growing tree is water or [https://en.wikipedia.org/wiki/Sap '''Sap''']. Freshly [https://en.wikipedia.org/wiki/Felling '''Felled'''] or [https://en.wikipedia.org/wiki/Green_wood '''''Green'''''] timber with such a high [https://en.wikipedia.org/wiki/Water_content '''Moisture Content (MC)'''] is susceptible to attack by [https://en.wikipedia.org/wiki/Wood-decay_fungus '''Fungi'''] and may crack, warp and twist if dried out too quickly.


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	=====Moisture Content=====		=====Moisture Content=====

	The most ~~commom~~ method of checking '''Moisture Content''' is to take advantage of how moisture affects [https://en.wikipedia.org/wiki/Electrical_resistance_and_conductance '''Electrical Resistance''']. An electrical resistance meter, or [https://en.wikipedia.org/wiki/Moisture_meter '''Moisture Meter'''], ''(specified in BS EN 13183-2: Moisture content of a piece of sawn timber. Estimation by electrical resistance method)'', has two probes which are pushed into the wood, about 300mm from the end, and a resistance reading taken which is automatically converted into '''Moisture Content'''. Other types of meter are available which avoid damage to the wood surface.		The most common method of checking '''Moisture Content''' is to take advantage of how moisture affects [https://en.wikipedia.org/wiki/Electrical_resistance_and_conductance '''Electrical Resistance''']. An electrical resistance meter, or [https://en.wikipedia.org/wiki/Moisture_meter '''Moisture Meter'''], ''(specified in BS EN 13183-2: Moisture content of a piece of sawn timber. Estimation by electrical resistance method)'', has two probes which are pushed into the wood, about 300mm from the end, and a resistance reading taken which is automatically converted into '''Moisture Content'''. Other types of meter are available which avoid damage to the wood surface.


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	'''Natural''' or '''Air''' [https://en.wikipedia.org/wiki/Seasoning_(wood) '''Seasoning'''] can reduce '''Moisture Content''' to 15-20% depending on local climatic conditions - but it takes time: 25mm thick '''[[Softwood]]''' boards stacked in Spring may reduce to 20% MC after 2-3 months and 50mm thick boards 3-4 months but these times are extended if the boards are stacked in Winter. '''[[Hardwood]]''' boards are in fact best stacked in Winter so that the ~~inital~~ drying is slower: 25mm boards could be ready the following summer but 50mm boards may take a full year or more.		'''Natural''' or '''Air''' [https://en.wikipedia.org/wiki/Seasoning_(wood) '''Seasoning'''] can reduce '''Moisture Content''' to 15-20% depending on local climatic conditions - but it takes time: 25mm thick '''[[Softwood]]''' boards stacked in Spring may reduce to 20% MC after 2-3 months and 50mm thick boards 3-4 months but these times are extended if the boards are stacked in Winter. '''[[Hardwood]]''' boards are in fact best stacked in Winter so that the initial drying is slower: 25mm boards could be ready the following summer but 50mm boards may take a full year or more.


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	[https://en.wikipedia.org/wiki/Wood_drying#Kiln_drying '''Kilns'''] are essentially brick-built chambers where temperature and humidity can be controlled using a combination of heating coils, fans and steam jets. Timber is stacked as for '''Natural''' [https://en.wikipedia.org/wiki/Seasoning_(wood) '''Seasoning'''] is placed in the kiln which is then closed and a drying programme suited to the particular timber species is initiated. ~~Humidy~~ is high at the start, to help avoid surface splits as a result of too rapid contraction, then is ~~gradualy~~ reduced and temperature increased until at the end, there is a flow of hot dry air.		[https://en.wikipedia.org/wiki/Wood_drying#Kiln_drying '''Kilns'''] are essentially brick-built chambers where temperature and humidity can be controlled using a combination of heating coils, fans and steam jets. Timber is stacked as for '''Natural''' [https://en.wikipedia.org/wiki/Seasoning_(wood) '''Seasoning'''] is placed in the kiln which is then closed and a drying programme suited to the particular timber species is initiated. Humidity is high at the start, to help avoid surface splits as a result of too rapid contraction, then is gradually reduced and temperature increased until at the end, there is a flow of hot dry air.

DT Online: Added Kilns

2018-01-07T12:46:07Z

Added Kilns

← Older revision		Revision as of 12:46, 7 January 2018
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	The most commom method of checking '''Moisture Content''' is to take advantage of how moisture affects [https://en.wikipedia.org/wiki/Electrical_resistance_and_conductance '''Electrical Resistance''']. An electrical resistance meter, or [https://en.wikipedia.org/wiki/Moisture_meter '''Moisture Meter'''], ''(specified in BS EN 13183-2: Moisture content of a piece of sawn timber. Estimation by electrical resistance method)'', has two probes which are pushed into the wood, about 300mm from the end, and a resistance reading taken which is automatically converted into '''Moisture Content'''. Other types of meter are available which avoid damage to the wood surface.		The most commom method of checking '''Moisture Content''' is to take advantage of how moisture affects [https://en.wikipedia.org/wiki/Electrical_resistance_and_conductance '''Electrical Resistance''']. An electrical resistance meter, or [https://en.wikipedia.org/wiki/Moisture_meter '''Moisture Meter'''], ''(specified in BS EN 13183-2: Moisture content of a piece of sawn timber. Estimation by electrical resistance method)'', has two probes which are pushed into the wood, about 300mm from the end, and a resistance reading taken which is automatically converted into '''Moisture Content'''. Other types of meter are available which avoid damage to the wood surface.


			More traditionally, '''Moisture Content''' is measured by taking a small wood sample and weighing it. The sample is then baked in an oven set at 100<sup>0</sup>C and checked regularly until no further weight loss occurs. The final weighing gives the dry weight and '''Moisture Content''' is calculated as follows:
			[[File:MoistureContentFormula.png\|600px\|center]]

	=====History=====		=====History=====
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	</span>		</span>
	----		----
			=====Natural Seasoning=====
			[[File:TimberStackLabelled.png\|400px\|right]]

			'''Natural''' or '''Air''' [https://en.wikipedia.org/wiki/Seasoning_(wood) '''Seasoning'''] is the traditional method of reducing the '''Moisture Content''' in wood. After '''[[Conversion]]''', boards of timber are stacked on open-sided sheds which are protected from sun and rain but through which air can circulate freely.


			The ends of boards are painted to avoid splitting by drying out too quickly, then stacked one above the other with thin strips of wood known as '''Stickers''' separating them to allow air to flow through. It is important the '''Stickers''' are placed vertically above each other to avoid undue warping or bending of the boards. '''Stickers''' are up to about 20-25mm thick and normally spaced about 700mm apart, but both their thickness and spacing can vary to control the air flow according to the timber species and sections. Boards are also separated from each other along the '''Stickers'''. Each timber stack is kept away from its neighbours and raised off the ground on bearers or piers.


			'''Natural''' or '''Air''' [https://en.wikipedia.org/wiki/Seasoning_(wood) '''Seasoning'''] can reduce '''Moisture Content''' to 15-20% depending on local climatic conditions - but it takes time: 25mm thick '''[[Softwood]]''' boards stacked in Spring may reduce to 20% MC after 2-3 months and 50mm thick boards 3-4 months but these times are extended if the boards are stacked in Winter. '''[[Hardwood]]''' boards are in fact best stacked in Winter so that the inital drying is slower: 25mm boards could be ready the following summer but 50mm boards may take a full year or more.


	[~~[File~~:~~TimberStackLabelled~~.~~png\|300px\|right~~]]		Following '''Natural''' or '''Air''' [https://en.wikipedia.org/wiki/Seasoning_(wood) '''Seasoning'''], any timber which is to be used for interior work should be stored inside the workshop for a period of time before being used to reduce the '''Moisture Content''' further.
	~~=====Natural Seasoning=====~~


	=====Kiln Seasoning=====		=====Kiln Seasoning=====

			'''Kiln''' [https://en.wikipedia.org/wiki/Seasoning_(wood) '''Seasoning'''] or '''Conditioning''' ''(aka '''Artificial Seasoning''')'' is the method now most commonly used, especially for '''[[Softwood]]''', because it is quicker and more economic. Care must be taken not to dry out timber too quickly otherwise the timber may split and crack or have severe stresses induced into it. '''Kiln''' [https://en.wikipedia.org/wiki/Seasoning_(wood) '''Seasoning'''] is often used following a shortened period of '''Natural''' [https://en.wikipedia.org/wiki/Seasoning_(wood) '''Seasoning'''] to help avoid this - especially for '''[[Hardwood]]'''.


			[https://en.wikipedia.org/wiki/Wood_drying#Kiln_drying '''Kilns'''] are essentially brick-built chambers where temperature and humidity can be controlled using a combination of heating coils, fans and steam jets. Timber is stacked as for '''Natural''' [https://en.wikipedia.org/wiki/Seasoning_(wood) '''Seasoning'''] is placed in the kiln which is then closed and a drying programme suited to the particular timber species is initiated. Humidy is high at the start, to help avoid surface splits as a result of too rapid contraction, then is gradualy reduced and temperature increased until at the end, there is a flow of hot dry air.


			[https://en.wikipedia.org/wiki/Wood_drying#Kiln_drying '''Kilns'''] are either static '''Compartment Kilns''' where the timber stack stays still and is exposed to a changing humidity/temperature programme, or '''Progressive Kilns''' in which the timber stack slowly moves through a changing humidity/temperature environment.


	[[Category:Timber]]		[[Category:Timber]]

DT Online: Added Note

2018-01-06T23:16:33Z

Added Note

← Older revision		Revision as of 23:16, 6 January 2018
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	There is evidence ''(e.g. in [https://en.wikipedia.org/wiki/De_Re_Aedificatoria '''De Re Aedificatoria'''] written by [https://en.wikipedia.org/wiki/Leon_Battista_Alberti '''Leon Battista Alberti'''] in the mid-15th Century)'' that this method was practiced also in '''[[:Category:Middle Ages\|Medieval Europe]]''' but this is not to say that all timber was '''Seasoned''' before use. The large timbers needed for house construction would have taken years to '''Season''' naturally and [https://en.wikipedia.org/wiki/Green_wood '''''Green'''''] timber is easier to work. A high proportion of the timbers in medieval buildings were riven or [https://en.wikipedia.org/wiki/Cleaving_axe#Cleaving '''Cleaved'''] - additionally, joints were not only easier to cut into [https://en.wikipedia.org/wiki/Green_wood '''''Green'''''] timber but may shrink and tighten over time ''(ref: ‘Traditional Timber Framing - A Brief Introduction’ from University of the West of England)''.		There is evidence ''(e.g. in [https://en.wikipedia.org/wiki/De_Re_Aedificatoria '''De Re Aedificatoria'''] written by [https://en.wikipedia.org/wiki/Leon_Battista_Alberti '''Leon Battista Alberti'''] in the mid-15th Century)'' that this method was practiced also in '''[[:Category:Middle Ages\|Medieval Europe]]''' but this is not to say that all timber was '''Seasoned''' before use. The large timbers needed for house construction would have taken years to '''Season''' naturally and [https://en.wikipedia.org/wiki/Green_wood '''''Green'''''] timber is easier to work. A high proportion of the timbers in medieval buildings were riven or [https://en.wikipedia.org/wiki/Cleaving_axe#Cleaving '''Cleaved'''] - additionally, joints were not only easier to cut into [https://en.wikipedia.org/wiki/Green_wood '''''Green'''''] timber but may shrink and tighten over time ''(ref: ‘Traditional Timber Framing - A Brief Introduction’ from University of the West of England)''.
			----
			<span style="color: green">'''Note:'''
	It is probable ~~therefore,~~ that the cracks, bends and twists we now see in the timbers of old buildings which have survived, are the result of the timbers ‘'''Seasoning''' in situ’ as it were, and have probably been a feature of the building since early in its life, requiring constant patching up and filling with plaster etc.		It is probable that the cracks, bends and twists we now see in the timbers of old buildings which have survived, are the result of the timbers ‘'''Seasoning''' in situ’ as it were, and have probably been a feature of the building since early in its life, requiring constant patching up and filling with plaster etc.
			</span>
			----

	[[File:TimberStackLabelled.png\|300px\|right]]		[[File:TimberStackLabelled.png\|300px\|right]]

DT Online at 19:54, 6 January 2018

2018-01-06T19:54:12Z

← Older revision		Revision as of 19:54, 6 January 2018
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	[https://en.wikipedia.org/wiki/Wood_drying '''Seasoning'''] is a controlled drying process to reduce the [https://en.wikipedia.org/wiki/Water_content '''Moisture Content (MC)'''] of the '''[[Timber Conversion\|Converted]]''' timber until it approximates the surroundings or environment where it will be used. This [https://en.wikipedia.org/wiki/Equilibrium_moisture_content '''Equilibrium Moisture Content (EMC)'''] and ranges from10% to a 20% approximately, dependent on whether for interior or exterior use.		[https://en.wikipedia.org/wiki/Wood_drying '''Seasoning'''] is a controlled drying process to reduce the [https://en.wikipedia.org/wiki/Water_content '''Moisture Content (MC)'''] of the '''[[Timber Conversion\|Converted]]''' timber until it approximates the surroundings or environment where it will be used. This [https://en.wikipedia.org/wiki/Equilibrium_moisture_content '''Equilibrium Moisture Content (EMC)'''] and ranges from10% to a 20% approximately, dependent on whether for interior or exterior use.



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	There is evidence ''(e.g. in [https://en.wikipedia.org/wiki/De_Re_Aedificatoria '''De Re Aedificatoria'''] written by [https://en.wikipedia.org/wiki/Leon_Battista_Alberti '''Leon Battista Alberti'''] in the mid-15th Century)'' that this method was practiced also in '''[[:Category:Middle Ages\|Medieval Europe]]''' but this is not to say that all timber was '''Seasoned''' before use. The large timbers needed for house construction would have taken years to '''Season''' naturally and [https://en.wikipedia.org/wiki/Green_wood '''''Green'''''] timber is easier to work. A high proportion of the timbers in medieval buildings were riven or [https://en.wikipedia.org/wiki/Cleaving_axe#Cleaving '''Cleaved'''] - ''(ref: ‘Traditional Timber Framing - A Brief Introduction’ from University of the West of England)''.		There is evidence ''(e.g. in [https://en.wikipedia.org/wiki/De_Re_Aedificatoria '''De Re Aedificatoria'''] written by [https://en.wikipedia.org/wiki/Leon_Battista_Alberti '''Leon Battista Alberti'''] in the mid-15th Century)'' that this method was practiced also in '''[[:Category:Middle Ages\|Medieval Europe]]''' but this is not to say that all timber was '''Seasoned''' before use. The large timbers needed for house construction would have taken years to '''Season''' naturally and [https://en.wikipedia.org/wiki/Green_wood '''''Green'''''] timber is easier to work. A high proportion of the timbers in medieval buildings were riven or [https://en.wikipedia.org/wiki/Cleaving_axe#Cleaving '''Cleaved'''] - additionally, joints were not only easier to cut into [https://en.wikipedia.org/wiki/Green_wood '''''Green'''''] timber but may shrink and tighten over time ''(ref: ‘Traditional Timber Framing - A Brief Introduction’ from University of the West of England)''.


			It is probable therefore, that the cracks, bends and twists we now see in the timbers of old buildings which have survived, are the result of the timbers ‘'''Seasoning''' in situ’ as it were, and have probably been a feature of the building since early in its life, requiring constant patching up and filling with plaster etc.

DT Online: Added History

2018-01-06T17:36:15Z

Added History

New page

[[File:The World almanac and encyclopedia (1908) (14781760244).jpg|450px|right|The World almanac and encyclopedia (1908) (14781760244)]]
__TOC__

=====Introduction=====

Over half the weight of a growing tree is water or [https://en.wikipedia.org/wiki/Sap '''Sap''']. Freshy [https://en.wikipedia.org/wiki/Felling '''Felled'''] or [https://en.wikipedia.org/wiki/Green_wood '''''Green'''''] timber with such a high [https://en.wikipedia.org/wiki/Water_content '''Moisture Content (MC)'''] is susceptible to attack by [https://en.wikipedia.org/wiki/Wood-decay_fungus '''Fungi'''] and may crack, warp and twist if dried out too quickly.

Timber with greater than 20% MC is prone to decay and shrinkage starts as the timber dries below approximately 30% MC.

[https://en.wikipedia.org/wiki/Wood_drying '''Seasoning'''] is a controlled drying process to reduce the [https://en.wikipedia.org/wiki/Water_content '''Moisture Content (MC)'''] of the '''[[Timber Conversion|Converted]]''' timber until it approximates the surroundings or environment where it will be used. This [https://en.wikipedia.org/wiki/Equilibrium_moisture_content '''Equilibrium Moisture Content (EMC)'''] and ranges from10% to a 20% approximately, dependent on whether for interior or exterior use.

=====Moisture Content=====

The most commom method of checking '''Moisture Content''' is to take advantage of how moisture affects [https://en.wikipedia.org/wiki/Electrical_resistance_and_conductance '''Electrical Resistance''']. An electrical resistance meter, or [https://en.wikipedia.org/wiki/Moisture_meter '''Moisture Meter'''], ''(specified in BS EN 13183-2: Moisture content of a piece of sawn timber. Estimation by electrical resistance method)'', has two probes which are pushed into the wood, about 300mm from the end, and a resistance reading taken which is automatically converted into '''Moisture Content'''. Other types of meter are available which avoid damage to the wood surface.

=====History=====

[https://en.wikipedia.org/wiki/Vitruvius '''Vitruvius'''], a military engineer who served the Roman army under [https://en.wikipedia.org/wiki/Julius_Caesar Julius Caesar], specialised in the construction of '''[[:Category:The Romans|Siege Weapons]]''' for which he needed to source large timbers. He was concerned about what we would now call '''Moisture Content''' and '''Seasoning''' before use to reduce the risk of cracking and distortion. In his book [https://en.wikipedia.org/wiki/De_architectura '''De Architectura'''] he states: ''In felling a tree we should cut into the trunk of it to the very heart, and then leave it standing so that the sap may drain out drop by drop throughout the whole of it. . . . . Then and not till then, the tree being drained dry and the sap no longer dripping, let it be felled and it will be in the highest state of usefulness''. In other words, the tree is killed, but left standing until dry enough for use.

There is evidence ''(e.g. in [https://en.wikipedia.org/wiki/De_Re_Aedificatoria '''De Re Aedificatoria'''] written by [https://en.wikipedia.org/wiki/Leon_Battista_Alberti '''Leon Battista Alberti'''] in the mid-15th Century)'' that this method was practiced also in '''[[:Category:Middle Ages|Medieval Europe]]''' but this is not to say that all timber was '''Seasoned''' before use. The large timbers needed for house construction would have taken years to '''Season''' naturally and [https://en.wikipedia.org/wiki/Green_wood '''''Green'''''] timber is easier to work. A high proportion of the timbers in medieval buildings were riven or [https://en.wikipedia.org/wiki/Cleaving_axe#Cleaving '''Cleaved'''] - ''(ref: ‘Traditional Timber Framing - A Brief Introduction’ from University of the West of England)''.

[[File:TimberStackLabelled.png|300px|right]]
=====Natural Seasoning=====

=====Kiln Seasoning=====

[[Category:Timber]]