1 / 6

SEASONING

SEASONING. Seasoning Reducing moisture content appropriate for timber indoors Minimising in-service shrinkage to enhance dimensional stability of product. Removal of moisture from wood Free moisture Bound moisture. Seasoning processes Air seasoning (drying) Kiln seasoning (drying)

osmond
Download Presentation

SEASONING

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. SEASONING • Seasoning • Reducing moisture content appropriate for timber indoors • Minimising in-service shrinkage to enhance dimensional stability of product • Removal of moisture from wood • Free moisture • Bound moisture • Seasoning processes • Air seasoning (drying) • Kiln seasoning (drying) • Solar kiln seasoning (drying) • Reconditioning • Avoiding shrinkage or collapse during processing

  2. Moisture in wood • Growing Trees • saturated cells - voids filled and water in cell walls • sapwood - hollow cells transmit nutrients and water • heartwood - waste liquids stored in cells • Moisture Content • Growing tree -saturated ~120% • Free water – moisture in cell voids • Bound water – moisture in cell walls • Fibre Saturation Point (fsp) ~25% no water in hollow cells, but cell walls still saturated – all bound water remains • Equilibrium Moisture Content (emc) ~10 to 18% moisture content in equilibrium with service environment – bound water in equilibrium with atmospheric moisture fsp

  3. Moisture in wood • Seasoning • Removes some of the moisture from the wood during processing • Seasoned timber wont lose further moisture in service – minimal shrinkage • Free water • Moisture lost from hollow cells first (to fsp) • Bound water • More energy required to remove moisture from cell walls (to emc) fsp emc

  4. Air seasoning • Ambient air circulating around timber to remove moisture • Stacked timber separated to allow circulation • horizontal spaces • vertical “stickers” or “strips” • often ends wrapped or painted to slow moisture loss through end grain • In hot climates stacks are roofed to stop sun bleaching timber • Inexpensive • no drying energy required • very slow ~6 months to 2 years per 50 mm thickness • large area for storage required

  5. Kiln seasoning • Energy to give rapid drying of timber • Heated air and steam introduced to charged kiln • Circulation of heated air controlled by baffles and fans to give even distribution in the kiln • Kiln Drying Schedules • Temperature, air flow, humidity varied to give optimum drying • Kiln drying schedules varied for different species • Typically 20 - 40 hours to dry to ~12% • Reconditioning • Short duration steaming to repair any damaged surface cells

  6. Solar seasoning • Controlled environment using solar energy • gives faster drying with better control than air seasoning • is less expensive than kiln seasoning • Solar Kilns • Use collectors, fans and baffles to control air movement and temperature • Many designs available

More Related