Introduction
What is required of a non-returnable box?
Why use a non-returnable box?
Types of non-returnable box
The types compared
Which box is best?
This note explains what is required of a non-returnable box in the fish industry and why it is used. The main types of box are described and their advantages and disadvantages are discussed. Cartons for frozen fish or other special containers for fish products are not included.
No particular type of box is recommended, since it is unlikely that there will ever be a single best design for all types of journey; however, materials like fibreboard and expanded polystyrene have, in recent years, replaced wood to a considerable extent and this trend may continue.
When the kilogram replaces the pound as the accepted unit of weight in the fish industry, the opportunity should be taken to establish a standard range of boxes whose dimensions allow room for enough ice as well as the required weight of fish. Where existing boxes are described in the note, their nominal capacity is expressed in pounds, but SI units are used where-ever possible; for information on SI units sec Advisory Note 40, Metrication in the fish industry, by J. Templeton.
The non-returnable box in the fish industry is used principally for the carriage of wet fish and ice, or of smoked fish, on a single journey from the port wholesaler to the retailer, often by way of an inland wholesaler.
The box is required to protect the contents throughout the journey against damage or loss and to keep the fish clean and wholesome; after the journey has been completed, the box is discarded. The material from which the box is made should not transfer odours or other objectionable or harmful material to the fish.
The box may be used on a long journey that involves several transhipments into and out of depots and from one form of transport to another, or it may be carried only a short distance on one merchant’s lorry. The box may remain in the hands of one company throughout the journey, or it may be carried between merchants by both public and private hauliers. A box that is robust enough for the short simple journey may be quite inadequate for a long and complex one. Since a box is not normally designed for a specific route, it has to be able to withstand the worst handling conditions normally encountered on any route.
The non-returnable box may be required to carry amounts of fish ranging from 1-40 kg, but the most popular sizes are likely to be in the range of 5-15 kg; typical traditional units are 1 and 2 stones. Wet fish or fillets have to be kept chilled during the journey and this means there has to be room in the box for a sufficient amount of ice in addition to the correct weight of fish.
The traditional 2-stone box has enough room for 2 stone of fish and about 6 lb of ice, but the amount of ice carried in practice can vary from 4-8 lb in boxes coming off the same packing line. This amount of ice is barely sufficient to cool the fish and keep it cool on an average journey; the box should be big enough to hold at least one part of ice by weight to three parts of fish, and ideally one part to two. This would mean providing enough room for 4-6 kg of ice in a box carrying 12 kg of fish; obviously there is an understandable reluctance to do this because the cost of packaging and transport is increased, although the cost of the ice itself is small.
The box has to withstand normal conditions of handling, which may include blows, knocks, cuts, abrasions, deforming pressures, vibrations and the destructive effects of water and fish juices. However, a box built to withstand very rough handling might be too strong and therefore too expensive. Improved handling methods may reduce the strength requirements for new designs.
A non-returnable box, since it makes only one journey, has to be the cheapest container that can do the job satisfactorily; materials that are too strong or too hard-wearing are an unjustifiable luxury; constructional and fastening methods must also be cheap. Used boxes can create a disposal problem when they are made of materials that are not easily destroyed.
It is an advantage, for storage and handling purposes, if the box can be supplied in a knockdown form which is easily and quickly erected.
Improvements in box design, where increased costs are involved, are always difficult to justify; the trade is not easily persuaded to pay more for a better box when existing types appear to serve their purpose.
The non-returnable box has several important advantages over the returnable one for inland transport of fish.
With the use of a new, clean box for every journey the fish are more likely to be carried under hygienic conditions, and the presentation of the product to the retailer in a new container enhances its sales appeal.
Returnable boxes dispatched to retailers all over the country are extremely difficult and expensive to recover, and are expensive to repair and clean. The consignor can avoid the trouble and expense of accounting for their movements by making use of non-returnable boxes.
New designs of box, either from existing or new materials, are continually being produced, but many prototypes fail because they are too expensive; the three types in commercial use at present are the wooden box, the fibreboard box and the expanded polystyrene box.
THE WOODEN BOX
The material for the wooden box is usually rough whitewood, typically Portuguese pine, the pieces being imported already cut to size. The sides, bottom and lid are usually thin slats 5-6 mm thick, and the ends about 13 mm thick. The pieces are fastened with round wire nails, and the box may be strengthened by metal clips along the long bottom edges or by a flat metal strap nailed around the girth. All but the smallest sizes of wooden box are usually banded girthwise with round wire after filling and closing.
THE FIBREBOARD BOX
Fibreboard boxes for wet fish are made from solid board coated with a water repellent; boxes for smoked fish are often of untreated fibreboard, sometimes corrugated. The base and lid, which are separate pieces, are usually supplied flat from the board mill and erected by the user, the comers being overlapped 100-130 mm and fastened by staples. The lid is as deep as the base and is a push fit over it. The filled lidded box is normally strapped girthwise with round wire to increase mechanical strength and reduce pilfering. Drain holes are provided in the four bottom comers of the wet fish box; some users have additional holes cut in the walls.
THE EXPANDED POLYSTYRENE BOX
Polystyrene beads containing a volatile blowing agent are partially expanded, matured and then blown into moulds where they are fused and fully expanded by steam to form either the box or the lid. The wall thickness, typically 9-13 mm, is fixed by the designed size of the mould, but the density of the material can be varied by controlling the pre-expansion of the beads. The strength of the box depends on the density of the material and also on the efficiency of the fusion process; water can percolate between beads not properly fused, to make the box soggy, but a well fused box is unaffected by water.
The base has drain holes formed in the bottom. The lid, which is not as deep as the base, is usually a push fit onto it. The filled lidded box is often dispatched without fastenings of any kind, but tape, wire or string around the girth is sometimes used.
Since a moulded box, unlike the wooden and fibreboard ones, cannot be dispatched flat, the moulding plant is preferably located near to the user to keep down transport cost.
OTHER TYPES
New designs employing new materials, particularly plastics, are continually being made, but most of them fail because they cannot be made both tough enough and cheap enough. Attempts have been made to produce a box that contains the meltwater within a separate compartment in the box, so that it can be used without restriction on all kinds of transport along with other cargoes. A moulded polyethylene box with a heat sealed lid, first tried in Canada, has been demonstrated in the UK, and prototypes made from polypropylene and polyvinylchloride (pvc) have also been tried; none has so far proved a serious rival to the established commercial designs.
The advantages and disadvantages of each kind of box can be summarized, but it must be remembered that the conditions of service are so varied that what may be quite satisfactory for one merchant may be useless for another; in practice, one port wholesaler may use all three common types of non-returnable box to suit particular routes and particular customers, while another may find one design satisfactory for his whole trade.
MECHANICAL STRENGTH
The wooden box stacks well, withstands rough handling fairly well and, if damaged, is fairly easily repaired at a transfer point. The strength of the box is not significantly affected when the wood is wet, although the nails tend to lose their grip. Because the box is of slatted construction, fish may be squeezed through the gaps between sides and bottom, and dirty meltwater can contaminate the contents. The box does not often collapse completely, and the contents are usually intact on arrival.
The fibreboard box withstands rough handling better than other types, and has good stacking properties when the boxes are stacked squarely on one another, so that the weight is taken by the strengthened sides and comers. The stack may be unstable when weight is put on the centre of the unsupported lid, or when the lid is bulged by overfilling the box. Water-repellent fibreboard of good quality is not significantly affected by water.
Expanded polystyrene boxes are more easily damaged by rough handling than wood or fibreboard ones and for this reason are not much used in the larger sizes, but are satisfactory when handled carefully. They stack well and are usually fitted with locating lugs to ensure that they stack squarely. The strength of well fused polystyrene is unaffected by water.
A drop test that simulates commercial handling has been devised to measure the performance of prototype boxes.
INSULATION
A box that insulates the contents and allows most efficient use of the ice has a distinct advantage.
Fibreboard and wet wood are not very good insulating materials compared with expanded polystyrene; in addition the polystyrene box has thicker walls than the other boxes and consequently should use the available ice more effectively. When chilled fish are packed in plenty of ice in a single polystyrene box, they will arrive cooler after a long warm journey than those in a wooden or fibreboard box. This advantage is often less marked in practice because boxes of any material in stacks will tend to insulate one another, and because too little ice may be put on warm fish which is often as high as 10° C. When boxes are carried in insulated transport, the insulating value of the individual box is less important.
A thermal test has been devised to measure the effect of the insulating property of a box.
APPEARANCE AND HYGIENE
An attractive package that displays the contents to advantage is an increasingly important requirement in the food industry. Rough white wood cannot be colour printed as elegantly as smooth fibreboard; the moulded polystyrene box has limited possibilities for printing, but the white material is attractive to look at.
Both the fibreboard and the polystyrene box protect the contents against contamination in transit better than the wooden box because its slatted form offers much less protection to the food inside.
LABELLING AND FASTENING
Labels can be easily tacked or stapled to wood or fibreboard; labelling of polystyrene boxes is more difficult and requires either a special stapler or writing on the box surface.
The lid of the wooden box can be easily secured by nailing and wiring, and the lid of the fibreboard box can be secured by wiring. The lid of the polystyrene box is more difficult to secure, and more expensive strapping is sometimes used. When the lids are left unfastened, pilferage is easier and the contents may fall out if the box is tipped end on or thrown. Ease and speed of fastening the lids on to boxes can be an important cost factor. A box with a push fit lid can be closed much faster than one which requires strapping and nailing.
WEIGHT
A wooden box to hold 5 kg of fish weighs about 1 kg; the same size of fibreboard box is less than half the weight of a wooden one, and a polystyrene box is a tenth of the weight of a wooden one. Reduction in box weight should mean a saving in total transport costs.
DISPOSAL
Disposal of wooden boxes is not usually a problem; they can sometimes be sold, as seed boxes for example, or used for firewood. Treated fibreboard cannot easily be pulped and has little or no resale value. The polystyrene box can sometimes be sold for other purposes like the wooden box; both the polystyrene and the fibreboard box can be burnt in a refuse incinerator, but they are bulky to handle and transport and can add to the disposal problems of the local authorities.
COST
The fibreboard box and the wooden box cost much the same; the polystyrene box usually costs a little more. The cost of a particular box from a manufacturer can be affected by the size of the order, the quality of finish requested, the amount of printing and, for wood and fibreboard, whether supplied erected or flat. Transport cost may be significant particularly for polystyrene boxes. The user must also take into account the cost of labelling, fastening, and carriage of the full box when making his choice.
Since the biggest item in the cost of a non-returnable box is the material of construction, there is a natural tendency to keep down the size of a box, often at the expense of room for enough ice. The cost of some raw materials, for example plastics, may not rise as much in future as wood; thus the polystyrene box may become more competitive. As transport and handling methods improve, the strength requirements and therefore the relative cost of the box may decrease. Demand for improved product quality may encourage the use of a roomier box that will protect the contents and hold sufficient ice to keep the contents chilled.
The wooden box is cheap, strong and rigid but it can be less hygienic and in some instances less attractive than other types of boxes. The fibreboard box costs about the same as the wooden one, protects the contents better and can be much more attractive in appearance. The expanded polystyrene box is more expensive and less strong, but provides some insulation, protects the contents and is attractive to look at. As handling and transport methods continue to improve, order of popularity of the various types of boxes could change.
When the fish distribution trade goes metric, there will be an
excellent opportunity to specify the dimensions of a standard range of
non-returnable fish boxes, and perhaps to specify materials and design in so far
as they affect the quality of fish as food.
