[17]The corkwood or cork of commerce is the external part or “periderm” of the cork-oak; and when it has attained a diameter of approximately 12.7 centimeters or the tree measures forty centimeters in circumference according to the Spanish governmental regulations, which the tree does usually by the time it is twenty years old, the bark may be removed. The stripping generally takes place during July and August, and it is a process which demands skill and care, if injury to the bark is to be avoided. In Algeria the French strippers sometimes use crescent-shaped saws, but under the usual Spanish method a hatchet, with a long handle, is the only implement employed. The bark is cut clear through, around the base of the tree, and a similar incision is made around the trunk, just below the spring of the main branches; the two incisions are then connected by one or two longitudinal cuts, following, so far as possible, the deepest of the natural cracks in the bark. Inserting the wedge-shaped handle, the tree’s covering is then pried off. The larger branches are stripped in the same manner, yielding, generally, a finer grade of cork than that of the trunk. The thickness of the bark ranges from 1.27 centimeters to 6.85 centimeters, while the yield also varies greatly from twenty to 75 kilograms[18] per tree, depending upon its size and age. After the first stripping the tree is left in the juvenescent state to regenerate, and great care must be taken in the stripping not to injure the inner skin or epidermis at any stage of the process, for the life of the tree depends upon its proper preservation, for if injured at any point, growth there ceases and the spot remains forever afterward scarred and uncovered. It is also necessary to avoid stripping during the prevalence of a sirocco, which would dry the inner skin too rapidly and therefore exclude all further formation of cork.

The Capgrand-Mothe system, which, as known, consists of dressing the trunk with the same cork just removed, and leaving it so dressed for a couple of months, has not met with approval, as being impracticable on a large scale. After the stripping, the phellogen, the seat of the growing processes, undertakes at once the formation of a new covering of finer texture, and each year this, the real skin, with its life-giving sap, forms two layers of cells, one within, increasing the diameter of the trunk, the other without, adding thickness to the sheathing of bark. After eight or ten years this sheathing is removed, and while more valuable than the first stripping, it is not as fine in quality as that of the third and subsequent strippings, which follow at regular intervals of about nine years. At the age of about forty years the oak begins to yield its best bark, continuing productive as a rule for almost a century.[19] The cork of the first barking is called Corcho-Bornio, Borniza or virgin, and is so coarse, rough, and dense in texture that it is of little commercial value. The second barking is called “pelas,” or secondary cork, and this and subsequent barkings constitute the cork of commerce. As the bark is removed it is gathered up in piles (rusque) and left for a few days to dry. Having been weighed, it is next carried either in wagons or on the backs of burros to the boiling station, where it is stacked and allowed to season for a few weeks. It is then ready for the boiling process. The outside of the bark in its natural state is, as may well be imagined, rough and woody, owing to exposure to the weather. After boiling this useless outer coating is readily scraped off, thereby reducing the weight of the material almost twenty per cent. The boiling process also serves to remove the tannic acid, increases the volume and elasticity of the bark, renders it soft and pliable and flattens it out for convenient packing. After being roughly sorted as to quality and thickness, the bark is then ready for its first long journey, and as the forests are generally located in hilly or even mountainous country, the faithful burro must again be called into service. Truly the Spaniards’ best friend, though the worst treated of all, these patient little animals present a most grotesque appearance when loaded from head to hind quarters with a huge mass of the light bark. Down from the hills they go in trains of thirty, forty or even a hundred, threading the rocky bridle paths in single file and wending their way through the narrow streets of quaint villages where traces of Moorish occupancy may still be seen, to the nearest railway station. The corkwood is there freighted to the various sea-port warehouses in Spain and Portugal, Seville, Spain being perhaps the largest depository and user of raw material.[20] This historic city, situated on the banks of the Guadalquivir, presents a very animated sight in the summer months, and plays a very important part in the cork industry, for besides the numerous warehouses for storing and shipping there are factories for the manipulation of cork and its conversion into the many useful forms in which it has proven of value. Before shipping, the bales are opened, the edges of the bark trimmed and the bark then sorted into the various grades of quality and thickness again. The importance of this last mentioned operation cannot be overemphasized, as the whole problem of the successful and economical manufacture of corks center about it. After sorting it is ready to be rebaled for shipment, this generally being done by placing the large, flat pieces called planks or tables, at the bottom of the bales, and above them the small pieces which are covered in turn with larger sections; then the whole mass being subjected to pressure to render it compact, afterward being bound up securely with steel hoops or wires. Each bale carefully marked indicating the grade or quality, loaded directly into ocean-going steamers and shipped to the ports of the world.

From this meager description we at least can learn what “corkwood” is, the limited sphere of its growth, the constant care necessary to insure a successful harvest or gathering, the peculiarities of the tree, its longevity and the general mode of preparing the bark for shipment; the narration in no wise doing justice to this most interesting material, in its natural state, for its growing is a fascinating tale in itself; but for the purpose of this writing the foregoing has been deemed sufficient to convey an understanding of it.

As we have now seen how this wonderful material grows, its haunts and dwellings, we will look at it more closely and see what it really is, how this particular formation comes about and its peculiarities.