RESOURCE 11 SEASONING TIMBER IN A COMPARTMENT KILN

RESOURCE 11: SEASONING TIMBER IN A COMPARTMENT KILN JUNIOR CYCLE WOOD TECHNOLOGY STRAND: Wood Science & Materials During the seasoning process the timber SCIENCE Sticker material is prone to LINK Spacers shrinkage and ‘shake’, cracking of timber, due to microscopic cellular deformation as a result Fan to Extract of heat and pressure. Planning & Management, Communication ELEMENT: and Environment & Sustainability LEARNING OUTCOMES: 3. 2, 3. 3, 3. 5 & 3. 11 NOTES Compartment Kiln Seasoning is an artificial process for removing moisture from timber. The purpose of seasoning is to dry the timber from its raw ‘wet state’ to a ‘dry state, which makes it workable and less prone to decay in the form of rot (fungal). However, not all of the moisture is removed from the timber as seasoning to 15%-22% moisture content (M. C. ) is deemed suitable. Compartment kiln seasoning is a favourable method as it is quick and adaptable allowing different types of timber to be seasoned to their required levels. The seasoning process involves timber being stacked on a trolley and separated with sticker spacers. Once in the Compartment Kiln, the following occurs: § § § Forced air circulation by using large fans, blowers, etc. Heat of some form provided by piped steam. Humidity control provided by steam jets. Throughout this process, moisture is constantly being drawn out of the timber, which in its raw ‘wet state’ contains 25 -30% water moisture. Compartment Kiln seasoning is a relatively quick but expensive process and is often used to season expensive timber material. Let the Season-‘ing’ Begin! Compartment Kiln Timber Stack Moist Air ‘A Look at how Timber is Seasoned Seasoning Defects. TRACKER LEARNING in a Compartment Kiln’ Hot Pipes to Heat Air JC KEY SKILLS Bow KEY SKILL ELEMENTS Crook STATEMENTS OF LEARNING Cup LEARNING OUTCOMES ACTION VERBS Twist KEY QUESTIONS Fungal Attack 3 -2 -1 STUDENT REFLECTION Equilibrium Moisture Content (EMC) is the BEING LITERATE, BEING NUMERATE, STAYING WELL, MANAGING INFORMATION & THINKING, COMMUNICATING, moisture content of wood MANAGING MYSELF AND WORKING WITH OTHERS below the EXPRESSING IDEAS CLEARLY & ACCURATELY, EXPRESSING IDEAS MATHEMATICALLY, THINKING CRITICALLY & fibre saturation CREATIVELY, USING LANGUAGE, BEING RESPONSIBLE/SAFE/ETHICAL AND SETTING/ACHIEVING PERSONAL point (FSP) is a function of GOALS AND CO-OPERATING both relative humidity and SOL 15 temperature of surrounding air. 3. 2, 3. 3, 3. 5 & 3. 11 Fibre saturation point Timber Stack EVALUATE, UNDERSTAND, EXPLAIN AND INVESTIGATE (FSP) is a term used in wood mechanics and especially WHAT ARE THE ADVANTAGES OF KILN SEASONING? wood drying, to denote the HOW ARE MOISTURE LEVELS LOWERED IN TIMBER DURING COMPARTMENT KILN SEASONING? point in the drying process WHY IS COMPARTMENT KILN SEASONING AN EXPENSIVE PROCESS ? at which only water bound 3 THINGS I LEARNED – WRITE IT ON THE PAGE in the cell walls remains 2 THINGS I WANT TO KNOW MORE ABOUT – WRITE IT ON THE PAGE with all other water, called 1 QUESTION I STILL HAVE – WRITE IT ON THE PAGE free water, having been removed from the cell cavities. Steam Jets If the wet weight of a piece of timber is 240 grams (g) and its dry weight is 200 g, then what is the moisture Moisture Content Formula content (M. C. ) of the MATHS Wet Weight – Dry Weight x 100 = Moisture Content (%) piece of timber? LINK Dry Weight Individual Cell JUNIOR CYCLE WO O D T E C H N O L O G Y SCOILNET PDST JOE LYSTER 2019/20 RESOURCES