GCP (NRB): Section 4 (NRB): Non-returnable bottles and packaging materials

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1 Institute of Brewing and Distilling General Certificate in Beer Packaging (GCP) Section 4 NRB Specialist Section Non-returnable Bottles (NRB) and Packaging Materials. 4.1 NRB: Bottle Design Shape gives strength Many sizes 180ml to 680ml Logoised Clear and green glass allows UV light to spoil beer Broken glass is hazardous especially neck slivers from poorly moulded bottles Exact dimensions are vital as bottles are filled to a level Bottles must accept a crown cork Other dimensions limited by size of washer pockets, star wheels etc Returnable bottles are heavier and more expensive 1 The following summarises the important features of design of Non-returnable glass bottles: Material Shape Affect on beer quality Resistance to wear & tear Glass Beer bottles are round. Circular shapes have the strength to withstand the internal pressures generated during filling and pasteurising. Virtually nil; glass is very smooth and easy to clean, it is also insoluble and cannot taint the beer. Glass is translucent and clear or green bottles allow UV light to cause lightstruck flavours in the beer. Amber (brown) glass protects beer almost totally against light-striking flavour effects. Depends on the thickness of the bottle. Returnable bottles are heavier than non-returnable. There is a tendency to move to a lighter weight of bottle to reduce costs.

2 2 Dimensions Special features The bottle s volume is important because, with machines filling to a level, the beer volume depends on the precision of the bottle s dimensions. The profile of the top of the bottle is important because it is required to seal on the filler head and onto the crown. Particles of broken glass are very difficult to detect in a bottle and procedures like rinsing, inspection and separation in case of burst bottles need to be in place to protect the consumer. The Glass Bottle It is useful to know the different parts of the bottle and these are given below: Sealing Surface Locking Ring Mouth or Bore Finish Neck Reinforcing Ring Shoulder Neck Label Mould Seam Body Label Back Label Foot Label Heel or Insweep Label Panel Base (Push up) Stippling

3 3 Glass is an inorganic substance fused at high temperature and cooled so that it solidifies in a vitreous or non-crystalline condition. All commercial glass is based on silica which is the principal component of sand. Common beach sand is unsuitable for making commercial glass since it contains impurities and varies widely in composition. However, there are large deposits of high purity silica sands available in many parts of the world. Glass bottle manufacturing today is a very capital intensive process a typical furnace costing 25M with an expected life of yrs. It has a high energy usage with a melting temperature of around 1500 C and a continuous operation for 365 days per year. 4.2 NRB: Glass Materials Sand (Silica) is mixed with other materials in order to lower the temperature and allow glass to melt, mix well and release any trapped air. A typical mix or batch is: Silica 70% Soda Ash 15% Limestone 9% Refining Agents } Colourants } 6% De-colourisers } Cullet (broken glass) is normally added at the rate 30-75% and this reduces the temperature required for the melt to below 1500 o C, saving up to 10% of the energy consumed. The raw materials are weighed in batches and mixed. The resultant mix is then added continuously in order to maintain a consistent level of 1.5 to 2 metres in the furnace. A furnace is dedicated to one colour, which is usually: White flint (clear) Amber, for UV sensitive products or for decoration Green, for decoration In order to achieve a colour, colorants are added to the batch. Also if there is colour present when a clear flint bottle is requires, decolourisers are added. Iron in sand, for instance, will give a greenish tint which is due to the iron content of the sand. Amber - iron, sulphur, carbon Green - chromium oxides Blue - cobalt oxides Selenium (red) and cobalt (blue) oxides are used as decolourisers

4 4 Glass Melting Most furnaces today use natural gas, and the fire from one side of the furnace. The hot air is exhausted at the other side into a regenerator. The heat generated melts the batch as it travels through the furnace. A temperature of up to 1500 o C is generated, over the surface of the batch, which melts as it floats through the furnace on the surface of the molten glass. The process is carefully controlled the mix and temperatures must be consistent in order to ensure a good product. Any change will give rise to problems when the bottle is being produced. The molten glass now exits the furnace and shears cut the stream to create what is called the gob. The amount of glass in the gob is dependent on the temperature and composition of the glass, the size of the orifice, the length of stroke of the plunger and the timing of the shears. The gob then passes down a trough into the forming machine, which houses the bottle moulds The consistency of the glass is similar to thick syrup. Principles of Bottle Making There are three main processes for the production of glass containers: 1. Blow and Blow 2. Press and Blow 3. NNPB (Narrow Neck Press and Blow) Bottle Forming Bottle forming is essentially a two stage process. The blank side receives the gob and makes the blank or parison. This partly formed bottle is then transferred to the mould side and the parison is blow into the final shape. There are essentially three different processes. Blow and Blow Process Beverage bottles up till the late 1970s were all made by this process. The gob is dropped into the blank mould, then two puffs of compressed air are successively applied to each end of the blank. The parison is then transferred into the final mould and is blown to shape

5 5 It should be noted that while the parison is formed in the final stage, the air bubble may not form a perfect uniform internal shape, giving wall thickness variability. Press and Blow Process With this process the parison is not made by blowing but by being pressed into an exact shape by a plunger; this makes the process especially suitable for glass jars. Narrow Neck Press and Blow Process (NNPB) This modern process allows bottles which would normally been made using the blow and blow method, to be light-weighted by 10 to 20%, due to a consistent wall thickness. This process is usually restricted to light weight NRB and is not usually available for Returnable bottles. A high degree of precision is required with this technology and it is normal for manufacturers only to be interested in using this process when there is a large volume to be produced. Also the tooling cost is higher.

6 6 Surface treatment and annealing of bottles is necessary in order to give them inner and surface strength, and sufficient slip so that they run well down a packaging line. Annealing When a bottle leaves the forming machine its outer surface is hard having cooled to 300 o C; however, the inner part is still hot and soft. If cooling was to continue naturally, the inner parts would contract more than the outer cooler surface and dangerous stresses would develop. If a bottle is left to cool without annealing, it is so weak that if you give a tap with something metallic, it will implode! Annealing is therefore necessary and involves heating the bottle to 550 o C and then slowly cooling it down in a tunnel called the Lehr. Hot End Treatment This treatment is to protect the surface from abrasion. The layer consists of a metal oxide, usually tin. Titanium and zirconium can also be used. Tin is applied as a stannic chloride vapour and decomposes to the oxide during heating. If there is too much coating in the finish area of the bottle it can be blamed for promoting the rusting of crowns. This protective layer will gradually be dissolved over time making the bottle much more vulnerable to scuffing. Cold End Treatment This is carried out as the bottles emerge from the annealing layer. Bottles are still at a temperature of approx. 100 o C. Cold end treatments are soluble coatings (including polyethylene glycols and their esters) and are applied by spray heads that traverse backward and forward between the rows of bottles. These coatings allow the bottles to slip against each other and conveyors and act as lubricants. Bottle Faults and Testing Glass manufacturers adhere to an international standard which is why bottles in all countries have the same size of neck finish. The most common being the 28mm. All manufacturers carry out intensive automatic on-line and many off-line checks to ensure quality standards are maintained, so that packaging companies do not have to carry out quality checks on receipt. Manufacture of Crowns Types of Crown (Shell) Stainless Steel (SS) Electrolytic Tin Plate Tin Free Steel (TFS) which is electro-chrome coated steel

7 7 TFS is the most common. However tin plate gives more corrosion protection and maybe favoured when packs are shrink wrapped. It has a much shinier appearance and is more susceptible to scratching. SS is best for corrosion protection but is very expensive. If corrosion is to be avoided, bottles must be effectively dried under the crown skirt. This should be carried out with air jets before the labeller, at the correct angle, carrying high volume air at low pressure. Taking high pressure air off the ring main not an option; a stand alone air compressor is that the most satisfactory solution. crown from rusting. Also a corrosion inhibitor in the pasteurizer will assist in preventing the Originally a crown cork had a cork insert as a seal. This was not leak proof so an aluminium spot was used to cover the cork and act as a liner and seal. This was known as the aluspot crown. With the development of plastics the aluspot crown was replaced by a liquid PVC plastisol. These crowns have foamed liners which is forgiving when applied to returnable bottles which could have a slightly damaged sealing area. However when bottles are stacked on pallets without crate protection, the weight on the crown will flatten the plastic and could result in bottles on the lower pallets leaking. The most commonly used crown liners today are PVC and PVC-Free Dryblends. They are suitable for good pressure retention before and after pasteurization, stacking, oxygen barrier and scavenging with soft and hard polymers. A double lip design is used. The above crowns are used on bottles with a standard finish. However, a twist off crown needs to be profiled to fit the bottle finish. The same crowner can be used but the crown tolerances need to be better managed within the standard tolerance of 28.7mm+/-0.3mm.

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9 9 4.3 NRB: Packaging Materials Packaging materials are one of the vital parts of packaging and the understanding of them is important. So often a high speed machine fails to run as designed because the material purchased has not been properly specified for that machine. The following defines Primary, Secondary and Tertiary packaging Primary The product cannot be sold without these materials. They contain the product and meet legislation e.g. bottle, crown and label or can and can end with product and best before information Examples Bottles (Glass, Aluminium & PET), Crowns (Tin Free Steel, Tinned or Stainless Steel), Roll on Closures (ROC), Labels or Sleeves (Paper, OPP - Oriented Polypropylene, PVC - Polyvinyl Chloride). Secondary This effectively is the material that collates the primary package in some form i.e. a second layer of packaging. This turns the primary package into a saleable or marketable unit Examples Board (Carton, Tray, Layer Board, Kraft & Corrugated, Sleeve Wrap & Multi-packs (Board & Film), FEC (Board & Film), Crates. Tertiary This relates to the remainder of the packaging. It is really there to protect the finished product, and allow it to be transported safely, and without damage, to its final destination. Examples Pallets, Locator Boards, Stretch & Shrink Film, Tray/Shrink (If it is covering Secondary) Packaging Materials Functions There are two main functions of packaging, these are: Technical Functions Marketing Functions a) Technical Functions Containment Holds contents without leakage Protection Product does not hurt the consumer Preservation Product will keep for the period described as the shelf life of the product which be up to the best before date and is not responsible for imparting flavours

10 10 Measurement Holds the legally declared quantity Storage Will travel and store successfully b) Marketing Functions Communication Product name and anything else about the product Display Looks good on the shelf. Neat, tidy and well packaged Information Contents, ABV, Best Before, Batch Number and any other relevant information which will normally be a legal requirement Promotion Packaging is often used to promote a product a peelable label for example Selling Final packaging will sell the product Materials Specifications The functions can be understood, but it is important that the materials that are purchased enable the final package to function as perceived. Poor specifications can be responsible for issues on the packaging line or in trade. These specifications also need to be controlled. One approach, to make control easier, is to divide the specification into three parts. The first part is an overall policy statement. This would normally relate to a restriction in chemical treatment or the use of compounds which could affect the product. This would include the requirement for tests, should the supplier wish to use a different form of treatment; for example, the use of a different lacquer inside a beverage can. It may also include an environmentally based statement that requires a percentage of the supplied material to be recycled. This of course needs to be done with great sensitivity, as some materials will have a significantly reduced performance if there is a recycled content. The second part will cover all components that come under a common heading, such as bottles, cans, trays, cartons, film etc. This will include the general description, technical requirements, quality and environment specific to the component. Finally, the third part will be specific to the actual component, giving dimensions, type of material, barcodes, artwork and so on. This is agreed with the supplier and with other parties, such as marketing, sales and manufacturing. As and when components are added or changed there is a minimum quantity of documentation involved whether it is computer based or in a file. Each component is given a code either alphanumeric or numeric