Where a packer puts up pulp in 5–gal. cans for his own use during the winter months he ought to be able to get two years’ use out of all of his cans, and three years out of a large percentage of them. It is questionable whether it is ever advisable to use a can over three seasons. One reaches a point where the percentage of swells is so large with old cans that the saving of the cans is unprofitable. When a new can is first used, the year should be indelibly stamped on the can, so that at any time the packer can go through his stock of used cans and tell how many seasons’ use each can has had. This will prove a help in making a decision on which cans are worth holding over for another season, and which ones are not. It also gives him a line on the kind of can that gives him the most value for his money.
Enamel lined cans are now being used a great deal, and as a rule they seem to give a little better service than the plain tin, although this is not always the case. Some packers think the enamel imparts a very slight foreign taste to the pulp, but I have never been able to detect it. Enameling or lacquering of the outside of the cans is essential if there is not sufficient sheltered storage for the pulp, or if it must be stacked in a damp warehouse. An excessive amount of moisture in the air will quickly start the tin to rusting on plain cans, and many cannery warerooms are entirely too moist for stacking cans, as they are near the process room, and the air is often misty with the presence of condensing steam from the process tanks. If there is ample dry storage space, the outside enameling of the cans does not seem to be an advantage.
Washing and Drying Cans
When the season’s pack of pulp is being worked up, the cans which are to be saved for another season’s use should be thoroughly washed out in a tub with hot water. Spraying devices will not work, as the top of the can will probably have a layer of pulp stuck to it, due to the receding of the pulp in the can when it cooled, and even a heavy spray will not remove all of this. The cans must be partially filled with hot water and shaken hard to properly clean them. The foreman should inspect the washed cans at frequent intervals by means of a small electric light which is wired to a short rod and which can easily be inserted in the can through the cap hole. If the washing is not thoroughly done this will show it up quickly.
After as much of the water as possible is shaken out of the cans they should be put in a drying oven and left over night. In the morning the cans should be thoroughly dry if sufficient steam is kept in the oven radiators. The oven is made with a partition which divides it into two parts, and one part can be filled with the wet cans while the other side is being emptied of the dry cans.
Protection From Dust
After the cans are dried, a pasteboard insert should be placed in the cap holes to keep the dust out of them while they are in storage during the winter and spring. One of the can companies at least, supplies these pasteboard inserts or inverted caps with their cans, and they fit snugly into the cap hole.
Testing Used Cans
Before the old cans are used the following year they should all be tested for pin hole leaks and the leaks patched up. They should then be re-tested and not used until they are shown to be tight under air pressure when immersed in water. This can be done during the spring and summer months, and the packer can then be reasonably sure that his old cans are in good shape for the next season’s run. If the cans are very old and the seams are very rusty, new pin holes will be opened up every time air pressure is put in them. Such cans should, of course, be thrown away.