SUPPORT MARKS.--It frequently occurs that one sees across the middle of smoked sheets a wide mark. This is where the wooden support in the smoking-chamber has been. As a rule, even in the most careful cases a faint mark may always be seen, but in many instances this mark is exaggerated to such an extent as to point to lack of care on the part of the store supervision. If bays of racks remain empty over-night, they may possibly become covered with a light sprinkling of fine wood-ash and tarry deposit. Wet rubber placed upon these racks will pick up and retain the impurities, and more often than not they cannot be washed out. It is incumbent upon the manager to see that empty racks are thoroughly cleansed before placing wet rubber upon them. The better plan is to arrange that the bars can be removed easily from sockets. There should be in stock sufficient "spares" for, say, two days' rubber. When the dry rubber is removed, the bars should likewise be taken away, to be cleansed and kept in the factory until again required. This will ensure that fresh rubber always rests upon a clean support. On some estates, in order to guard against a pronounced "bar-mark," sheets are moved and turned daily. In other smoke-houses the upper surface of the bar is chiselled in concave form, so as to admit of the passage of smoke below the surface resting on the bar. STICKINESS.--This is not to be confounded with "tackiness," from which the rubber does not recover. Stickiness is only temporary, and may be remedied. As a general rule, it is due to packing sheets, which have not a good raised "ribbing," and which may have been coated with light tarry deposits (see Glaze). This surface film may be removed by washing the sheets, or scrubbing them, with cold water. Usually a further two days' air-drying will make the rubber fit for packing; and if the smoke-curing has been efficient, there should be no need to anticipate trouble from mildew. Some estates adopt this practice daily with success, as a form of insurance against complaints of surface deposits. RIBBING, SURFACE PATTERN.--While we know that the passing of sheets of rubber between rolls, causing a particular raised pattern to appear, has no effect upon the actual quality of the rubber, there is a great deal of practical advantage gained. The practice ensures an increase of superficial area which is an aid in drying, improves the appearance of the rubber for selling purposes, and is of distinct advantage in enabling the rubber when packed to travel in better condition. Sheets do not become so closely packed; sampling and general handling are easier on delivery.