CONTRIBUTORS - WOOD WORKS
HERE IS SOME ADDITIONAL INFORMATION ON THE PROPERTIES OF RED IVORY FOR THE WOOD ENTHUSIAST :
RED IVORY : HARD FACTS
Botanical / scientific name :
Trade name :
Berchemia zeyheri ( Family : Rhamnaceae )
Red Ivory ( Other names : Pink Ivory , Mutiwenkosi , umNini , Pau-rosa ( Mozambique )
Origin :
Conservation status :
Bole characteristics :
South Africa , Swaziland , Mozambique and Botswana . The species occurs in open woodland ,
Not endangered or protected .
A shrub to small tree , up to 10m in height . Large , straight logs are very difficult to find . often on termite mounds , on rocky ridges and along watercourses .
The stems are often divided or short and badly shaped .
Colour : The heartwood is pale pink to deep red . The yellowish sapwood is clearly defined . Grain pattern :
Density ( at 12 % moisture content ):
Strength / bending properties :
Seasoning :
Durability and preservative treatment :
Working and finishing properties :
Straight to interlocked . The texture is very fine and even .
The air-dry density ranges from 990 to 1 100kg / m 3 , with an average of 1 040kg / m 3 .
The wood seasons slowly , with 25mm boards taking up to a year to air-dry . Surface checking and end splitting will occur if boards are exposed to the
The wood seasons well , but rather slowly with very little shrinkage .
The wood is very durable and resistant to borer and fungi .
The wood saws quite easily despite its hardness . Tungsten-tipped saw teeth are recommended . Wet wood has an unpleasant , ‘ damp ’ smell when being milled . Boards without interlocked or wavy grain plane well to a smooth finish . When sanding , the sandpaper tends to clog up quickly .
The wood is not lustrous and has no characteristic odour .
sun and drying under cover is essential to minimise this . Kiln-drying schedule 1 is recommended ( see below ).
Both air- and kiln-drying can be done with no or very slight drying defects and once dry , the timber is remarkably stable in use .
It is extremely resistant to preservative treatment .
The wood takes paint and varnish well . Varnishes containing ultra-violet filters are recommended to preserve the heartwood colour and prevent it from turning brown . The bark and sap are reported to be irritants and may cause dermatitis and poisoning .
TIMBER DRYING SCHEDULE FOR RED IVORY ( Berchemia zeyheri ) Supplied by H-P Stöhr , Timber Drying Institute ( timberdrying @ mweb . co . za )
Dry Bulb temperatures (° C ) and Relative Humidity (%) at the following Timber Moisture Contents
Drying schedule no .
Green 40 % 30 % 18 % to final DB RH % DB RH % DB RH % DB RH %
1 35 77 40 65 45 53 60 32
DB = Dry bulb temperature , RH = Relative Humidity Please note : Drying schedules only serve as a guide to the kiln operator , with the response of the timber to the drying condition being the criterion .
REFERENCES AND SOURCES
1 . Coates-Palgrave , M . 2002 . Keith Coates-Palgrave Trees of Southern Africa , Random House Struik , Cape Town . 2 . Dyer , S , James , B and James , D . 2016 . Guide to the Properties and Uses of Southern African Wood . Briza Publishers , Pretoria . 3 . Flynn , JH and Holder , CD ( ed .) 2001 . A Guide to Useful Woods of the World . Forest Products Society , Madison , WI .
58 APRIL / MAY 2017 //