Forest Utilization and Wood Technology Questions and Answers

Answer: C

The fixative is chromium.

In water-soluble 'fixed' preservatives such as copper-chrome-arsenic (CCA) and acid copper chromate, the chromium compound reacts with the wood after treatment and fixes the toxic copper and arsenic in insoluble forms, so they are not washed out by rain or soil water.

Chlorides, fluorides and sulphides do not act as fixatives; fluoride salts are themselves leachable preservatives.

Answer: B

The tree called 'Anjan' is Hardwickia binata.

Anjan is a tree of the dry deciduous forests of central and southern India, in the family Fabaceae. It is often pollarded for fodder, and its bark yields a strong reddish-brown fibre used for making ropes; its wood is also very hard and heavy.

Trema orientalis belongs to the Cannabaceae, Grewia optiva to the Malvaceae, and Butea monosperma (palas) is a Fabaceae tree but is not called Anjan.

Answer: B

The major cooking chemical is sodium hydroxide (NaOH).

In the sulphate (kraft) process, wood chips are cooked in white liquor, a solution of sodium hydroxide and sodium sulphide, which dissolves the lignin and frees the cellulose fibres. The process takes its name from the sodium sulphate added to make up chemical losses, which is reduced to sodium sulphide in the recovery furnace.

So sodium sulphate is the make-up chemical rather than the cooking agent, the trap in option D. Sodium nitrate and sodium chloride are not used in the process.

Answer: B

The key's answer is at the end of rainy season.

Sal (Shorea robusta) is a highly refractory timber that splits and checks badly if it dries too fast. Stacking it for air seasoning at the end of the rains means the early, critical drying takes place in the mild, humid weather of the post-monsoon and winter months, so moisture leaves slowly and evenly.

Starting in the hot, dry season would dry the surface too quickly and cause cracking, and starting in or at the end of winter brings the timber into the hot weather while it is still wet.

Answer: B

Sal wood is classed as highly refractory.

In seasoning, 'refractory' woods are those that tend to crack, split and warp when dried. Sal (Shorea robusta) is dense and dries slowly with a strong tendency to surface cracking and end splitting, so it is placed in the highly refractory class and must be seasoned slowly, under cover.

Light woods such as semal, which dry quickly without serious defects, are non-refractory, and the moderately refractory class lies between the two.

Answer: C

The board described is particle board.

Particle board is made from wood chips, shavings, sawdust or other lignocellulosic material such as bagasse, mixed with a synthetic resin binder and pressed under heat and pressure, sometimes with a catalyst. It uses wood waste and small-sized material that cannot be made into timber.

Fibre board is made from wood broken down into fibres, not fragments, and usually relies on the fibres' own bonding. Sandwich and core boards are layered composites with a core between face layers.

Answer: C

Good-quality cricket bats are made from Salix alba, the white willow.

The variety Salix alba var. caerulea, known as cricket bat willow, gives a light, tough, resilient wood that does not split on impact. English willow from this tree is used for the best bats, and Kashmir willow for cheaper ones.

Populus deltoides (poplar) is used for plywood and matchwood, Celtis australis (printed 'oustralis') for fodder and small timber, and Salix tetrasperma is the Indian willow, not the cricket bat willow.

Answer: D

The width of the cut made by a saw is called the kerf.

The kerf is slightly wider than the saw blade because the teeth are set (bent alternately) or swaged. Kerf width matters in sawmilling, since everything inside it becomes sawdust and is lost from the log.

The gullet is the space at the base of each tooth that carries sawdust out of the cut, and the pitch is the distance between the tips of adjacent teeth.

Answer: D

The key's answer is hardness.

The gross (general) features of wood used for identification are those seen or sensed without magnification: colour, odour, lustre, texture, grain, figure and weight. They are judged by eye, nose and hand on a freshly cut surface.

Hardness, the resistance of wood to indentation, is a mechanical property measured by testing (for example the Janka test), so it is the one not counted among the gross physical features.