DEAS 935: 2018
ICS 55.120
 
© EAC 2018                                                                                                                            First Edition 2018 
 
DRAFT EAST AFRICAN STANDARD 
Packaging — Code of practice  — Part 1: Glass containers 
 
EAST AFRICAN COMMUNITY DEAS 935: 2018 
ii © EAC 2018 – All rights reserved
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Violators may be prosecuted. DEAS 935: 2018 
© EAC 2018 – All rights reserved  iii
 Foreword 
Development of the East African Standards has been necessitated  by the need for harmonizing requirements 
governing quality of products and services in the East African Community. It is envisaged that through 
harmonized standardization, trade barriers that are encountered  when goods and services are exchanged 
within the Community will be removed.  
The Community has established an East African Standards Committ ee (EASC) mandated to develop and 
issue East African Standards (EAS).The Committee is composed of  representatives of the National Standards 
Bodies in Partner States, together with the representatives fro m the public and private sector organizations in 
the community.  
East African Standards are developed through Technical Committe es that are representative of key 
stakeholders including government, academia, consumer groups, p rivate sector and other interested parties. 
Draft East African Standards are circulated to stakeholders thr ough the National Standards Bodies in the 
Partner States. The comments received are discussed and incorpo rated before finalization of standards, in 
accordance with the Principles and procedures for development o f East African Standards.  
East African Standards are subject to review, to keep pace with  technological advances. Users of the East 
African Standards are therefore expected to ensure that they al ways have the latest versions of the standards 
they are implementing .  
The committee responsible for this document is Technical Commit tee EASC/TC 066, Packaging . 
Attention is drawn to the possibility that some of the elements  of this document may be subject of patent 
rights. EAC shall not be held responsible for identifying any o r all such patent rights. 
During the preparation of this Standard, reference was made to the following document: 
BS 1133-18, Packaging code — Section 18: Packaging in glass  
Acknowledgment is hereby made for the assistance derived from t his source. 
 DRAFT EAST AFRICAN S TANDARD DEAS 935: 2018
 
© EAC 2018 – All rights reserved 1
 Packaging — Code of practice — Part 1: Glass containers 
1 Scope 
This Draft East African Standard gives guidelines on the manufa cture, types, selection and use of glass 
containers for packaging  
2 Normative references 
There are no normative references in this standard.  
3 General considerations 
3.1 Most solids and liquids can be packaged in glass containers, w hich are made in a wide variety of 
shapes, sizes and colours to meet the commercial, marketing and  technical requirements of modern retailing. 
Typical examples are products associated with the food, drinks,  cosmetics, pharmaceutical and household 
products industries. 
3.3 The performance of glass container improves with optimized dist ribution of glass material in the 
container. 
3.4 The use of surface treatments or Hot-end and Coating and Cold-e nd Coating improves the performance 
of containers’ Glass weight may also be reduced, without sacrif icing performance, if the surface of the 
container is coated with Hot-end and Coating and Cold-end Coati ng (Polymer based material) at the earliest 
stage of manufacture that is practicable. 
3.5 Leakage or contamination can be avoided by using metallic or p lastic closures suitable for vacuum, 
hermetic and pressure retention. 
Improvements in glass containers are being paralleled by work i n the complementary closure manufacturing 
industry. Containment is effected by means of a seal material i nstalled at the edge of the closure and 
coinciding with the position of the glass finish (i.e. that par t of the glass container which supports the closure) 
permitting the container to be easily opened and resealed many times.  
3.6 The satisfactory service performance of a glass container on th e filling line and in the market-place 
depends on the co-ordination of many elements of design. In the  filling hall, consideration should be given to 
handling on the filling line, cleaning, filling, labelling, cap ping, processing and the application of retail 
packaging.  
Between the glass manufacturin g plant and the filling hall, the  container should be transported and for this 
purpose appropriate packaging has to be designed and specified.  Beyond the filling line, the filled container 
has to be transported into the retail distribution system and t hen perform in the retail and consumer 
environment. Once empty a refillable container should be return ed for filling and a non-refillable container 
should be recycled. 
3.7 In addition to all the handling criteria, it is essential that t he requirements of the product to be packed 
are also incorporated into the designed the shape of the neck, type of finish and closure can be determined by 
nature of packed product i.e whether liquid or solid  
In the case of a liquid, the designer should consider if it is non-carbonated, carbonated or alcoholic or 
pasteurized. If it is a solid the designer should consider whet her it is heat processed i.e. pasteurized or 
sterilized, hot filled, moisture absorbing, sensitive to ultrav iolet light etc. 
  
2 © EAC 2018 – All rights reserved
 3.8 The designer should take into account factors that could influ ence a consumer’s purchasing decision. 
e.g. container shape, product and/or customer image, colour, de coration, embossing. The design should be 
compatible with the requirements of the glass manufacturing pro cess.  
4 Manufacture of glass containers 
4.1 Raw materials and glass composition 
The main raw materials for glass production include but not lim ited to, sand of low iron content, limestone, and 
Soda ash. 
The range of glass compositions most commonly used as shown in Table 1. 
Table 1 — Range of commonly used glass compositions 
Chemical constituent Range of compositions 
(%) 
Silica (SiO 2) 70 - 74 
Soda( Na 2O) 11 - 14 
Lime (CaO) 11 - 11.5 
Potash (K 2O) 0.2 - 0.5 
Magnesia (MgO) 10 - 11.5 
Alumina (Al 2 O3 ) 1 - 2 
Baria (BaO) 0 - 0.5 
Iron oxide (Fe 2O3 ) 0.003 - 0.5 
 
NOTE Range of commonly used glass compositions may vary 
4.2 To improve the physical and chemical performance of glass cont ainers, other materials such as blast 
furnace slag, dolomite and calcium sulphate sodium sulphate or sodium nitrate, are added. Selenium and 
cobalt are added as decolorizers to neutralize the colouring ef fect of any residual iron, which may be present 
in the sand. 
4.3 Coloured glass 
Flint or white glass can be coloured by the addition of suitabl e materials to the batch. The more common 
colours are amber (iron oxide and sulphur), green (chromium oxi d e  a n d  i r o n  o x i d e )  a n d  o p a l  
(fluorides).Certain products are traditionally linked with glas s containers of a particular colour e.g. beer in 
amber bottles. 
4.3.2 Small quantities of coloured containers can be produced by addi ng  ox ides ( frits) to th e for e h ea rth 
associated with a particular forming machine or by spraying org anic colouring materials, such as polyurethane 
resins, on to bottles which are then cured. 
4.4 Production of glass containers 4.4.1 The production of glass containers starts with unloading of raw  materials into silos. The materials are 
drawn from the silos as required, weighed, mixed and charged me chanically into the glass melting furnace. 
Attention is given to the accuracy of weighing and consistency of mixing. 
In order to melt the glass, the furnace operates at temperature s up to 1 600 °C. Instruments that measure and 
control the level of the glass, furnace pressure. Glass and fur nace temperatures to a high degree of accuracy 
are used. Instruments linked to the glass level measurement aut omatically control within limits the rate of 
batch feed. The firing of the furnace and the draught on the ch imney are also automatically controlled. As a  
© EAC 2018 – All rights reserved  3
 result of these furnace operations, refined glass emerges as a stream from an orifice at the end of a feeder 
channel or fore hearth which links the furnace to the bottle fo rming machinery.  
4.4.2 Several fore hearths may be associated with one melting furnace . The glass stream passes through 
an orifice and is automatically cut into lumps of glass, called  gobs, of a pre-determined mass, associated with 
the capacity of the container, by means of water cooled recipro cating shears. The gobs, whose temperature 
has been established accurately at a pre-determined level, are then fed into parison moulds which are 
supported on the glass container forming machine located beneat h the fore hearth. At this stage the bore, 
neck and finish of the container used for supporting the closur e is made whilst the body of the container is 
only partially formed. The parison shape is then transferred in to a second mould on the other side of the 
machine in which the final shape of the container body is blown . 
Narrow neck containers are made traditionally by the blow and b low process in which the parison cavity is 
formed pneumatically following the moulding of the finish aroun d a plug or plunger. Wide mouth containers 
such as jars are made by the press and blow process; the pariso n cavity and the finish are moulded by means 
of a plunger in one operation. Because the press and blow opera tion achieves better glass distribution, an 
adaptation of it is now in use fo r the production of light weig ht narrow neck containers of suitable design. 
4.4.3 The independent section machine which is almost universally use d for forming bottles is a series of 
individual adjacent sections each concerned with the total manu facturing cycle involving the formation of the 
glass finish and the final blowing of the bottle. The machine i s made up of a series of air operated 
mechanisms involved in progressing the orming cycle. Each has t o be precisely timed in sequence to ensure 
the conversion of the glass gob into an accurately formed conta iner within each section.  
This is achieved by means of studs on a rotating timing drum wi thin each section. The cam action of the studs 
actuates valves which admit operating air to the mechanisms thr ough a series of latches and levers. More 
recently, this mechanical system has been replaced by a much si mpler electronic system which depends on 
the use of magnetic valves for controlling the operating air to  the mechanism. In this way, more accurate 
timing has been achieved together with improved operator contro l since, with the electronic system, machine 
adjustments are made on a console which is separate from the bo ttle machine. With the mechanical system 
stud adjustments are made on the drum. 
The number of sections associated with the bottle making machin e can vary between 4 and 12; the number of 
gobs fed simultaneously from the fore hearth is usually 2 (doub le gob) although triple gob (3 gobs) and quad 
gob (4 gobs) operation are used where volume markets for partic ular glass designs exist. Single gob 
operation is used for the manufacture of larger capacity contai ners. Further developments of the 
manufacturing operation involve the addition of a turret on the  blow side of the machine to allow additional 
time within the forming cycle for the formation of the containe r body resulting in further improvements in glass 
distribution. After forming is complete, the glass container is  transferred on to a moving belt and conveyed to 
an annealing oven (lehr) where it is reheated to a temperature approaching 600 °C, the annealing point of the 
glass. Cooling of the glass at a controlled rate removes unacce ptable stresses from the container when at 
room temperature. The cooling rate is dependent on the design a nd weight of the container. 
4.4.4 Before and after annealing, the surfaces of containers are usua lly given a spray or vapour treatment 
to protect them by increasing their scratch resistance and by i mproving their surface lubricity which facilitates 
handling during subsequent operations in the glass plant, in pa ckaging and on the filling line. A typical 
treatment is stannic chloride applied at the hot end before ent ering the lehr. This reacts at the glass surface 
leaving a thin layer of tin oxide on the surface of the glass. As the bottles emerge from the lehr they are 
treated, for example, with polyethylene or oleic acid. After su rface treatment each glass container is 
automatically inspected for quality and dimensional accuracy by  a series of mechanically and electronically 
operated inspection devices. The most common method of packagin g is an assembly of cardboard trays or 
boards separating layers of glass containers, supported on pall ets and held together with shrink wrap material. 
This assembly is known as a bulk pallet. Other options are corr ugated cases supplied in the flat by the filler, 
erected at the glass manufacturer’s factory and used for the wa rehousing and transportation of empty 
containers, or similar service cartons that are the property of  the glass manufacturer, crates or packaging 
used for specialized markets such as cosmetics.  
4 © EAC 2018 – All rights reserved
 4.5 Semi-automatic methods 
A small but important part of the industry is concerned with su pplying relatively small quantities of glass 
containers often in special sizes (particularly larger sizes), shapes or colours. Semi-automatic equipment is 
used for this type of production, the glass being melted in sma ll pot furnaces and hand gathered on the end of 
an iron. Molten gobs are then fed into moulds in which the glas s is blown by manually controlled compressed 
air. 
4.6 Moulds in which glass containers are made 
Because of its ease of machinability and the lack of distortion  when in use at elevated temperatures, fine grain 
cast iron is used for the manufacture of moulds, although occas ionally steel or special alloys may be used for 
certain mould components. 
Moulds are machined to fine tolerances and inspected before use  and during use to ensure that wear has not 
changed the dimensions to an extent hereby the overall dimensio ns and capacity of the glass container are 
affected. Computer aided mould manufacture is developing rapidl y and greater accuracy and repeatability of 
dimensions between moulds has resulted particularly where the g eometry is complex, for example where non-
round cross sections are involved. Mould costs are a significan t proportion of total production costs and, in 
some cases, short production runs on automatic equipment may ha ve to bear a surcharge. Small variations, 
such as a change of finish, can usually be achieved with as mal l on-cost if a change of neck ring only is 
required. Standard designs for particular containers have been agreed at industry level by the British Glass 
Manufacturers Confederation. With these the buyer has the choic e of purchasing from stock exactly the same 
container from those manufacturers who have budgeted for such a  mould availability enabling smaller 
quantities of containers to be supplied. The incorporation of c ooling ducts within the mou ld structure to effect 
more uniform temperature distribution during manufacture can im prove control but can limit the size of 
containers which can be made by particular processes. 
5 Design 
Designing a glass container involves the consideration of a num ber of factors the most important of which are 
as follows: 
a) The container should be capable of being made on existing gl ass manufacturing plant and with 
available technology if a development programme is to be avoide d; 
b) The container should be capable of being handled and filled on the appropriate filling line which either 
exists and possesses defined constraints or is to be designed a nd built. In the latter case, factors 
involved in the design of the filling line and the container ca n be made to complement each other. 
c) The container should withstand the conditions involved in wa rehousing, transportation, retailing and 
ultimate use by the consumer without damage or breakage. 
d) The container should protect the contents from deterioration  within a defined product specification 
throughout a specified shelf life ensuring that the product rea ches the consumer in a satisfactory 
condition. 
e) The container should meet the appearance and display charact eristics required by customer and/or 
retailer. 
f) The consumer should be able to gain access to the glass pack age. Body and finish dimensions 
related to the performance of the closure and body surface text ures should be considered in relation 
to consumer convenience. 
g) The container should be capable of being inserted into a bot tle bank via the appropriate aperture to 
facilitate its disposal for recycling. When designing a contain er, some or all of these factors will 
interact and the final design will be a compromise. Most glass manufacturers have invested in 
Computer Aided Design equipment which enables the container to be designed in the presence of the 
customer and with the aim of obtaining his approval in the shor test possible time. Modern systems  
© EAC 2018 – All rights reserved  5
 enable an image of the new design to be created on a screen in three dimensions, colour and 
translucency; the image approximates closely to the appearance of the finished empty container. An 
accurate impression of the filled container can be created by i ncluding contained product and closure 
on the screen image. The screen image may also be modified acco rding to the requirements of the 
customer and any filling line constraints prior to the commence ment of any mould design and 
manufacture. 
6 Attributes of glass 
6.1 General 
Modern retailing methods and techniques involved in marketing f ood have resulted in many new requirements 
for glass packaging. A list of glass packaging attributes impor tant to those employed in the selection and 
purchase of packaging Materials. 
6.2 Transparency 
A significant marketing advantage for glass packaging is its tr ansparency enabling the contained product to be 
seen by the consumer. 
6.3 Quality 
Many consumers regard products packaged in glass as quality pro ducts. 
6.4 Strength 
Although glass is a brittle material, it possesses considerable  strength in terms of head load resistance. Glass 
is much stronger when in overall compression than in tension, a n important factor when considering the 
warehousing of empty and filled containers. The design of a gla ss container is important in determining head 
load resistance in relation to the capping operation, impact re sistance and the requirements of the filling line. 
When designed for the packaging of carbonated beverages, glass containers can withstand internal pressures 
corresponding to 4.5 volumes of carbonation at ambient temperat ures experienced in hot climates. Such 
bottles are submitted to internal pressure testing on a samplin g basis before they are finally approved for 
despatch. 
6.5 Shape 
Glass is a visco-elastic material having no definite melting po int. Shape can be induced into the final product 
because there is a gradual change in the viscosity of glass whi lst it is cooling. This property can be used to 
identify product and customer image. 
6.6 Chemical integrity 
The glass compositions used for container production are chemic ally resistant to all food products, both liquid 
and solid. No additional internal surface protection is require d. Closure design, material, and the compounds 
used to effect a seal between a glass finish and the closure ar e important factors to consider when designing 
glass packaging to ensure adequate protection for a particular product. Compatibility between closure material 
and contained product should also be considered. 
Because of their chemical stability, glass containers can be st ored for considerable periods in normal 
warehousing conditions without any surface deterioration. Under  certain warehouse conditions condensation 
can affect, for example, the adhesion of labels and the perform ance of closures. Substances extracted from 
glass surfaces are not associated with any known health hazard.   
6.7 Resistance to thermal shock 
All glass containers are annealed at temperatures up to 600 °C following manufacture to prevent stresses 
developing in the container as they cool to room temperature. T he softening temperature below which the 
bottle will not deform when it is in a free standing position i s a function of its design i.e. of its shape, weight  
6 © EAC 2018 – All rights reserved
 and capacity. Compositions of glass commonly used for container s are capable of resisting a degree of 
thermal shock consistent with commercial retorting, pasteurizin g and hot filling schedules. Glass containers 
designed to be refilled are usually submitted to thermal shock testing on a sampling basis before they are 
finally approved for despatch. 
6.8 Impermeability 
Glass is virtually impermeable to all gases. Diffusion rates fo r water vapour, carbon dioxide and the 
permanent gases, e.g. oxygen, are, for all practical purposes, zero. This is particularly important to the flavour 
retention and preservation of many foods and beverages. 
6.9 Decoration 
The appearance of a glass container can be changed by surface d ecoration; silk screen printing, ceramics 
pray, coating with plastics and acid etching are current techni ques. Silk screen printing in particular is used for 
labelling refillable milk bottles for advertising purposes. Pre -labelling has been adopted using PVC and 
polystyrene sleeves for non-refillable beer and soft drinks bot tles. Pre-labelling by means of sleeves gives the 
filler an increase in line efficiency and filled product output  as well as a package of reduced weight. Special 
arrangements need to be made for either creating stocks of pre- labelled empty bottles in the case of a multi-
flavour operation or establishing “just-in-time” delivery sched ules from the glass supplier. 
6.10 Refillable and non-refillable bottles 
The economics of distribution is a contributing factor in deter mining whether a glass container should be 
designed as a refillable or non-refillable container. Refillabl e containers are particularly suitable where there is 
an adequate transport system available for local deliveries to an established market e.g. milk, soft drinks and 
beer. Non-refillable containers are more suited to retail marke ts. 
6.11 Re-use 
Glass containers may be re-used in various ways in the home pro vided they have been designed for this 
purpose. An intended re-use for glass containers used for packa ging some food products (e.g. storage jars) 
has been designed into particular packages. 
WARNING Pre-labelled bottles should never be refilled with dang erous substances and non-refillable 
bottles should never be refilled with homemade drinks or other beverages. 
6.12 Use in microwave ovens 
Glass used for the manufacture of bottles is almost completely transparent to microwave radiation. Heat 
processed food products packaged in appropriately designed glas s containers can be placed in a microwave 
oven and rapidly reheated prior to serving. 
6.13 Tamper evidence 
The inherent properties of glass place it high amongst those pa c k a g i n g  m a t e r i a l s  w h i c h  a r e  d i f f i c u l t  t o  
penetrate. Glass packaging should also be equipped with a closu re system capable of demonstrating a 
complementary quality of tamper evidence. 
6.14  Measuring container bottles 
Glass bottles have the required rigidity and stability which en ables them to be manufactured. 
6.15 Recyclability 
Glass can be recycled and returned to the glass manufacturer fo r re-melting, resulting in significant savings in 
both energy and raw materials. Manufacturers have their own sch emes of collection of used and broken glass 
for recycling. Organizations may also partner to form associati on that collects used and broken glass for 
recycling.  
© EAC 2018 – All rights reserved  7
 6.16 Glass container weight 
6.16.1 By reducing the weight of a glass container to a value which is  consistent with its service 
requirements in the glass container factory, during warehousing  and transporting to the filler and the retailer, 
during filling and in the hands of the consumer, several econom ies are experienced as follows. 
a) More containers per tonne of glass are produced resulting in  a reduction of cost by reduced 
consumption of raw material and fuel. 
b) The energy content of transportation is reduced which is par ticularly significant in exported glass 
packaged products. 
c) The recovery of assets used for melting, forming, annealing and inspecting of glass containers is 
improved; less glass is melted which results in an extended fur nace life. 
6.16.2 The principles of light weighting are as follows: 
a) Bottles of the same capacity and shape which are produced by  the same production method will 
become progressively less stro ng as the amount of glass used in  their manufacture is reduced. 
b) Changing the design, however, can produce stronger bottles a t lighter weights. 
c) By observing certain design principles related to surface sh ape and area and surface to volume ratio 
(often at variance with marketing requirements) the amount of g lass required to achieve a specified 
capacity can be minimized. 
d) Bottles which are of the same shape, capacity and weight but  which have improved glass distribution 
brought about by improved control, good design, a change in the  method of the manufacture, or a 
combination of these factors will in general be stronger. 
e) For any glass bottle design th ere is a limiting weight below  which performance cannot be maintained. 
f) The effective strength of a glass container on a filling lin e or a glassworks conveyor can be 
maintained by hot end and cold end surface treatment which incr eases surface lubricity and reduces 
the effect of glass to glass con tact or glass to metal contact (conveyor guides, etc.). 
g) The intrinsic strength of glass can be improved by modifying  the glass structure so as to produce a 
thin surface layer of compression  as in the chemical strengthen ing process. 
h) By covering the surface of a glass container with a protecti ve material, which can be used as a label, 
surface damage arising from scuffing can be minimized or largel y avoided. Pre-labelling of glass 
containers in this way at the earliest stage of manufacture wil l improve strength and facilitate light 
weighting. 
i) Surface damage received by glass containers during handling can  be minimized with well designed 
equipment employing up-to-date engineering principles, a factor  which should be taken into account 
when assessing the degree of light weighting for a particular d esign for a particular filling line.  
7 Types of glass container 
7.1 Bottles and jars 
Bottles and jars can be round, shaped or multi-faceted, etc. ex cept for bottles for carbonated beverages, 
which should always be round. Most glass container manufacturer s will offer a range of standard lines. Some 
designs are standard within the industry and are supplied by al l glass manufacturers.  
8 © EAC 2018 – All rights reserved
 7.2 Tubular glass containers 
In addition to the more usual types of glass container there is  a range of small capacity tubular glass 
containers that is made from glass tubing. They are all-cylindr ical in shape and, with some exceptions, vary 
between 5 mm and 35 mm in diameter, 20 mm and 200 mm in length and 0.5 Ml and 100 mL in capacity. 
Depending upon the purpose for which the container is required they may be manufactured from borosilicate 
glass or soda glass tubing. 
a) Borosilicate glass, type 1 . Boric oxide increases the thermal shock resistance and chemical  
resistance of glass. Tubing made from this material, usually te rmed “neutral glass”, is used where 
repeated autoclaving is a part of the preparation procedures. B orosilicate glass should on form to the 
appropriate type 1 hydrolytic test requirement (see British Pha rmacopoeia) which is more stringent 
than those for soda glass compositions. If the surface of type 1 glass is spoilt during processing, for 
example by the application of excess heat, then its surface may  be returned to type 1 by sulphur 
treatment. 
b) Soda glass, type II and type III. The composition of these glasses is similar to that of glass us ed for 
the manufacture of bottles. Type II and type III should conform  to appropriate hydrolytic test 
requirements which determine the ability of the glass to resist  corrosion and flaking from medicinal 
liquids. Type II glass is surface treated to give a higher hydr olytic resistance than type III glass. The 
surface neutrality of type III glass can be improved by a surfa ce treatment with sulphur so that its 
hydrolytic resistance is increased to that of type II. Both glass types, borosilicate and  soda , are 
available in either amber or flint (colourless). 
Tubular containers may be divided into three main groups. 
a) Straight sided tubes . Suitable for all products where it is important that the openin g does notrestrict 
the filling of the tube e.g. table ts or powders. Closures used in this type of tube are usually cork, 
plastics or rubber. 
b) Vials . Suitable for all products where multi-dosage or small capacity is required. Most neck finishes 
including sprinkler are available. Closures made of cork, rubbe r, plastics, metal or aluminium are in 
general use; they may be threaded, snap on or crimp closures (a s used for injection vials). 
c) Ampoules. Usually made from neutral (borosilicate) tubing and of two main  types i.e. narrow stems 
for liquids and wide stems for powders. Sometimes, soda lime gl ass composition is used for the 
packaging of powders in ampoules. Stems are sealed in or drawn- off by the application of gas 
burners. Automatic machines  are availabl e for washing, filling a nd sealing the ampoules. 
8 Quality control and testing 
8.1 General 
Wherever possible and consistent with the shape of the bottle e ach will be submitted to some or all of the 
following tests. 
a) Squeeze testing to detect and remove containers which would have obvious failures in terms of 
cracks or crizzles. 
b) Plug and finish testing to check finish dimensions, which re late to the filling and capping operation. 
c) Body gauging to check body dimensions in relation to filling  line constraints.  
© EAC 2018 – All rights reserved  9
 d) Detection of checks, cracks and crizzles in sensitive areas of the container using photoelectric 
techniques. 
e) Quality image analysis whereby each container is compared to  a stored image of a defect free 
container primarily used to detect and reject inclusions or con taminants in the glass. 
f) Visual testing whereby each container is finally checked by an operator seated in front of an 
illuminated screen enabling a visual check to take place. 
8.2 Quality controls 
At every stage of the manufacturing process, starting with the raw materials through to the assessment of the 
glass and the finished product, samples are taken for checking against agreed specifications. The purchaser 
of glass containers will be particularly interested in the asse ssment of the finished product although he will 
want to know of preceding procedures and their correct implemen tation. 
Typical quality control procedures for the product are as follo ws. 
a) All finished bottles pass through a series of automatic and visual inspections. These concentrate 
mainly on the functional performance and safety aspects of the container. 
b) Each pallet is sampled and the bottles checked for dimension s and quality with particular attention 
being given to the presence or other wise of cracks and crizzle s in the glass. 
c) Each mould is sampled at regular intervals and the bottles s ubmitted to checks to confirm annealing, 
bottle capacity, glass weight, surface treatment, etc. 
d) If the containers are subject to heat processing, then sampl es from each mould are tested for 
resistance to thermal shock. 
e) At regular intervals samples are taken from across the lehr and checked independently for annealing. 
f) Wall thickness, body and finish dimensions are measured to c onfirm they are within the tolerances 
specified for the bottle  
g) In the case of carbonated beverage bottles, internal pressur e resistance measurements are made on 
samples from each mould taken from the lehr belt to confirm tha t their internal pressure resistance is 
above the level required for the carbonated product. 
9 Specifications 
9.1 The glass container specification drawing 
The glass container specification is a statement from the manuf acturer to the filler giving the dimensional and 
capacity tolerances to which the bottle has been made. Other de tails of the bottle, such as weight, are given 
on the specification, which also describes the position and for m of any required engraving. It can advise the 
conditions of use of the container which the designer took into  account when preparing the design. 
9.2 The packaging specification 
The safe and effective transportation of containers between the  factory and warehouse operated by the glass 
manufacturer and the filler and the subsequent method of feedin g the glass on to the filling line imposes a 
packaging requirement on the glass manufacturer, which also nee ds to be specified. There is, therefore, an 
increasing tendency for product specifications to reflect all e lements of the complete pack. Most glass 
containers are supplied to the filler as bulk packs i.e layers of glass containers separated by boards or trays, 
standing on pallets and held together by means of shrink wrap m aterial. Other forms of packaging involve 
service cartons supplied by the glass manufacturer and customer  cartons supplied as fiats by the filler,  
10 © EAC 2018 – All rights reserved
 erected by the glass manufacturer and then used as the means of  transportation to the filler’s plant. Crates 
are used for soft drinks and beer bottles and specialized packa ging is used for cosmetics and toiletry bottles. 
10 Storage 
Provided the bottles are well packed and stored in clean dry co nditions they will retain their initial cleanliness. 
In many cases it is not necessary to wash bottles before use. J ets of clean high pressure air are sometimes 
employed to remove dust or any loose particles before filling. For this to be effective the bottles should be 
completely dry at the time of ai r cleaning. Alternatively, a ri nsing operation to remove any loose particles of dirt 
and to pre-warm containers about to be hot filled is carried ou t on-line. Warehouses should undergo regular 
vermin and infestation surveys to ensure their freedom from rat s or other undesirable creatures. 
 DEAS 935: 2018 
 
© EAC 2018 – All rights reserved