The level of protection achieved by any wood treatment process is dependent on achieving a sufficient uptake and penetration of the treatment chemicals. This phenomenon is also applicable when considering chemical modification of any wood species. The desired changes in physical, mechanical or durability enhancement of treated species can only be achieved beyond a superficial treatment. For this, Gmelina wood grown in Nigeria was considered for chemical modification but had to initially be examined for its treatability. Samples of Gmelina wood were impregnated under pressure with a coloured solution (Rhodamine B) and variations in uptake along and across stem diameter were investigated. The outcome of this investigation showed that Gmelina wood had a maximum uptake less than 25%, while the mean penetration depth in the axial direction is less than 4mm, and much lower in the lateral direction (comprising of radial and tangential directions). Subsequently, further investigation carried out through qualitative anatomy with light microscopy and Scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDX) showed that aside from the presence tyloses which obstructed flow in the axial direction, needle-like crystals identified as calcium oxalate contributed to greater restriction to fluid flow in the lateral direction. Hence, it was concluded that alternative modification approach through thermal treatment will be a more viable option in the treatment of Gmelina wood.

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