Different Methods of Curing Tobacco. W: 



In flue-curing the aim of the grower must be to hasten the yel- 

 h>wing of the leaf under conditions so favourable that all the desir- 

 able changes in the leaf will take place in as short a time as possible. 

 ]Jut when all these necessary changes have occurred, and the leaf has 

 taken on the proper yellow colour, the curing must be so regulated 

 that the second stage in air-curing, that is, when the leaf begins to 

 dry, the red colour must be prevented. 



The barns used in flue-curing are generally small. The inside 

 dimensions are from 16 to 24 feet square, and from 16 to 20 feet in 

 height. 



No deflnite formula can be given for flue-curing, as so much 

 depends on the type of tobacco grown, the nature of the soils on 

 which they are grown, and the prevailing weather conditions during 

 the curing of the tobacco. The most important factors in controlling 

 the rate of curing are heat and moisture, and with these of course 

 ventilation, and in order to cure a barn successfully these factors must 

 lie so regulated that the leaf can take on its proper yellow colour, 

 after which the colour must be fixed so that no further change in 

 colour can take place. 



It shoidd not be very difficult to flue-cure a barn successfully if 

 the different stages which are to be observed in this method of curing 

 tobacco are carefully explained. If the whole plant is harvested, 

 there are four such stages, namely : (1) yellowing ; (2) fixing the 

 colour; (3) drying the leaf; and (4) drying the stalk. 



If only the leaf is harvested, then only the first three stages are 

 to be icckoned with. Although the split-stalk method of harvesting 

 tobacco is still preferred in the western portion of the flue-curing belt 

 in the States, the general tendency is to harvest the individual leaves 

 as they ripen. 



Yellowing. — It is very essential to have the barn filled in one 

 day, otherwise the tobacco may not all yellow at the same time. As 

 soon as the barn is filled with tobacco, a thermometer and an hygro- 

 meter are hung on the lower tier near the centre of the barn, and the 

 door and ventilators closed. A small fire is then started in the 

 furnace. 



The fire must be gradually increased, as it is essential to maintain 

 a moderate temperature during the yellowing of the leaf. During 

 this stage of curing the temperature must not be allowed to exceed 

 120° F., for at that temperature the leaf is quickly killed, and no 

 further change in the colour or properties of the leaf can take place. 

 It usually takes from 30 to 48 hours before the leaf is properly yellow. 

 It is therefore advisable to raise the temperature gradually uj) to 

 90° F., where it is kept until the tips and edges of the leaf show signs 

 of yellowing. The fire is again increased until the thermometer 

 registers 95° F., where the temperature is maintained until the green 

 colour disappears and the leaf takes on a pronounced yellow colour. 

 From 9 to 12 hours after the fire is started the hygrometer will begin 

 to show its utility by indicating that there is not sufficient moisture 

 in the barn for successful curing. If no artificial moisture is supplied, 

 the tobacco will dry out a green colour. If the moisture is insufficient, 

 the difference in temperature between the dry and wet bulbs of the 

 hygrometer will be more than four degrees. Artificial moisture must 

 at once be furnished. Water is usually sprayed on the floor and walls 

 below the tobacco, and sometimes wet bags are placed over the flues. 



