DRAFT TANZANIA STANDARD  
 
 
 GDC 4 (3) DTZS  Tableware -Glass Tablew are-Specification  
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
TANZANIA BUREAU OF STANDARDS  
 
 
 
©TBS 2021                                                                                                       1st    Edition
 
1 
 1. Scope  
 
This d raft Tanzania standard specifies requirements, method of sampling and te st for glass tableware.   
2. Normative references  
The following documents are referred to in the text in such a way that some or all of their content constitutes 
requirements of this document. For dated references, only the edition cited applies. For undated references, 
the latest edition of the referenced do cument (including any amendments) applies.  
ISO 7086 -1:2019 Glass hollowware in contact with food — Release of lead and cadmium — Part 1: Test 
method  
ISO 7086 -2:2000 Glass hollowware in contact with food  — Release of lead and cadmium  — Part 2: 
Permissible limits  
3. Terms and definitions  
For the purpose of this document, the following terms and definitions shall apply ; 
 
3.1 detergent resistance  
degree of resistance to the chemical action of detergents  
 
3.2 flat tableware  
glassware having an internal depth not exceeding 25 mm, measured from the lowest point to the horizontal 
plane passing through the point of overflow  
 
3.3 glass  
inorganic material produced by the complete fusion of raw materials at high temperature into a 
homogeneous liquid which is then cooled to a  rigid condition, essentially without crystallization  
 
Note 1 to entry: The material may be clear, coloured or opaque  
 
3.4 hollowware  
glassware having an internal depth greater than 25 mm, measured from the lowest point to the horizontal 
plane passing through the point of overflow  
 
Note 1 to entry: Hollowware is subdivided into three categories based on volume:  
— small: hollowware with a capacity of less than 600 ml;  
— large: hollowware with a capacity between 600 ml and 3 l;  
— storage: hollowware with a capac ity of 3 l or great er. 
 
3.5 table ware  
glass articles that are intended to be used in contact with foodstuffs  
 
3.6 thermal shock  
condition of stress brought about by a large temperature difference across a body  
  
2 
 4. Requirements  
4.1 General Requirements  
 
4.1.1  The glass tableware shall be as free as possible from strain and visible defects. It  shall be as far as 
possible free from any colour as seen transversely through the body, except in the case of coloured or 
decorated articles.  
 
4.1.2 The wall thickness of the glass tableware shall be the same throughout the circumference at any given 
level with tolerances of ±33 percent for thickness up to 2 mm, ± 25 percent for thickness above 2 mm and up 
to 3 mm and ± 20 percent for thickness above 3 mm at the said level excluding embossing, if any.  
 
4.1.3 The rim of the  glass  tableware shall be uniformly smooth and evenly finished.  
4.1.4 For glass t ableware with handles, the handles shall be well fused with the main body of the glass and 
shall be facing the spout, if provided. The centre of the top and the bottom parts of the handles shall be in 
the same vertical plane.  
4.1.5 For glass tableware with spout, the spout shall be well shaped and shall be such that it is possible to 
pour from it in a regular stream without the liquid clinging to the outer surface.  
4.1.6 The  glass tableware  shall be free from any colour as seen transversely through the body, except in the 
case  of coloured or decorated articles . 
4.1.7  The tableware shall be well formed and when placed on a horizontal pla ne shall rest  evenly and shall 
not rock.  
 
4.2 Specific Requirements  
 
4.2.1  Thermal shock  
The glass tableware shall not show any crack or damage when tested in accordance with the method given 
in Annex A.  
4.2.2  Limits release of Lead and Cadmium  
 
The permissible limits for Lead and cadmium for glass hollowware , when tested in accordance with ISO 
7086-1:2019 , shall conform to the requirements given in Table 1 . 
 
Table 1-Permissible limits for Lead and cadmium release  
 
Type of glass hollowware  Lead limit  mg/l (Maximum )  Cadmium limit  mg/l (Maxi mum)  
Small  1.5 0.5 
Large  0.75 0.25 
Storage  0.5 0.25 
 
4.2.3  Alkalinity  
When tested in accordance with A nnex  B, the tableware shall pass the test.  
4..2.4 Detergent resistance of ceramic decorations  
When test ed in accordance with Annex  C, the tableware  with ceramic decorations  shall pass the test . 
5. Packing and marking  
 
 5.1 Packing   
3 
 The tableware shall be packed in a suitable manner that shall not cause damage to its serviceability, either 
in stores or during transportation.  
5.2 Marking  
5.2.1  Each tableware  shall be legibly and indelibly marked either at the bottom or near the rim or on a label 
with the following information:  
a) Manufacturer's name or trade -mark, and  
b) Nominal capacity excluding flatware.  
5.2.2  The bulk package  of the tableware shall be  legibly and indelibly marked  as follows;  
a) Manufacturer's name or trade -mark, and  
b) No minal capacity  excluding flatware .  
6. Sampling  
 
6.1 Representative tableware shall be taken at random from anywhere and tested in  accordance with individual 
tests. For ascertaining the conformity of tableware to the  requirements, all test samples shall satisfy all the 
requirements of this standard  
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
  
4 
 ANNEX  A 
(Clause 4.2.1)  
THERMAL SHOCK TEST  
A-0. Principal  
A-0.1 Tableware is subjected to a sudden change of temperature and  examined for any cracks or damage.  
A-1. Apparatus  
A-1.1 For Flat Tableware  
A-1.1.1 Electrical Air -Oven — capable of being heated through a temperature  range of 35° to 120°C; 
provided with a thermometer, an air-stirrer  or circulator to ensure temperature uniformit y and also a 
thermostat capable of maintaining the temperature constant to ±1 deg up to 100°C.  
A-1.1.2 Water Sprayer — suitable for spraying cold water on the outside  of the flatware.  
A-1.2 For Table ware Other than Flatware  
A-1.2.1 Hot Water -Bath — provided with suitable means of heating, a  stirrer to ensure uniform temperature 
through the bath, a thermometer  capable of being read to an accuracy of ± 1 deg and a thermostat to control  
the temperature o f water to within 70° ± 1°C. 
A-1.2.2 Cold Water -Bath — provided with a stirrer to ensure uniformity  of temperature throughout the bath 
and a thermometer capable of being  read to an accuracy of ± 1 deg.  
A-1.2.3 Wire Net Basket — capable of holding tableware  upright and of  such a size as could easily transfer 
tableware from hot to cold water -bath.  
A-2. Procedure  
A-2.1 For Flat Tableware  
A-2.1.1 Heat the air -oven and adjust the temperature to within 67° ± 1°C.Quickly place the requisite number 
of samples in it  and maintain the temperature  for 30 minutes. Remove the samples one at a time by means 
of tongs with asbestos -covered tips and subject the outside of the ware to a  spray of cold water at 27° ± 
1°C, for a period of one minute, within 5 ± 1  seconds of takin g out of the oven. The inside of the fiat tableware 
shall not be wetted.  
A-2.2 For Tableware Other than Flatware  
A-2.2.1 Place the requisite number of samples into the wire net basket  in an upright position. Fill the baths 
with water and adjust the tempera tures  of hot and cold baths at 67° ± 1°C and 27° ± 1°C respectively. 
Immerse  the basket containing samples into the hot water -bath so that they are filled  with water. Allow to 
soak for 15 minutes at the temperature of 67° ± 1°C.  
A-2.2.2 Transfer the basket  containing samples filled with hot water to  the cold water -bath. The process of 
transference shall be completed within  10 ± 2 seconds. Immerse the samples completely in the cold water -
bath for a period of 2 minutes, without allowing cold water to enter th em. 
A-2.3 Samples shall be taken as having satisfied the requirements of the  test if they do not crack or break.  
     NOTE — Samples which have not broken shall not be subjected to other tests or use  
 
  
5 
 Annex  B 
 
(Clause 4.2.3 ) 
 
TEST FOR ALKALINITY  
 
B1. Apparatus  
 
B1.1 Autoclave — Capable of heating the test samples up to a temperature 121  °C. 
 
B1.2 White glazed tile  
 
B2. R eagents  
 
B2.1 Quality of regents — Analytical grade.  
 
B2.2 The following reagents are required  
B2.2.1 Strong methyl red solution — Dissolve 40 mg of methyl red in 75 ml of rectified spirit. Warm  if 
necessary to effect solution. Add 1.5 ml or a sufficient quantity of 0.05 M sodium hydroxide  solution to adjust 
the solution so that the colour corresponds to pH 5.2 and  dilute to 100 ml with water.  
B2.2.2 Acid methyl red solution — Mix 20 ml of ml of strong red solution (see Clause B2.2.1)  with 8.3 ml of 
0.02 ml with water.  
B3. P rocedure  
Fill the containers completely with warm water, empty and allow to drain for 30 seconds  removing the l ast 
drops of water by touching the inverted rim with filter paper; repeat the  washing three times. Fill the 
containers to their prescribed capacity with acid methyl red  solution, and seal by fusion  of the glass, or if 
this is not practicable, apply a loose ly fitting closure made of an inert material such as cellophan e sheet. 
Heat in an autoclave at a  temperature of 121 º C for half an hour, cool and examine the colour  of the 
solution. If  necessary when the containers are of coloured glass, remove the solution for  examination on to 
a thoroughly washed white glazed tile.  
B3.1 The glass passes the test if the colour of the test solution has not changed from pink to  the full yellow 
colour of methyl red, as indicated by comparing it with the colour of a  solution prepared by adding 0.1 ml of 
0.05 M sodium hydroxide to 10 ml of acid methyl  red solution.  
 
 
 
 
 
 
 
 
 
  
6 
 Annex  C 
 
(Clause 4.2.3)  
 
DETERGENT RESISTANCE OF CERAMIC DECORATIONS  ON GLASS TABLEWARE  
C.0 P rincipal  
This test method provides the means of estimating the qualitative performance of the glass enamel decorations 
that are exposed to high phosphate detergents during use.  
C.1 Apparatus  
C.1.1 Test Chamber  –A thermostatically controlled tank, preferably stainless steel, that will maintain a solution 
temperature of 60 ± 2 °C. 
C.1.2 Specimen Holder - A device for supporting the specimens to be evaluated in such a manner as to ensure 
free and unobstructed contact between the decoration and the test solution.  
C.2 Reagents  
C.2.1 Prepare a test solution of 5% of sodium pyro - phosphate (Na 4P2O7.10H 2O) and 95% distilled water.  
C.3 Procedure  
C.3.1 Immerses the sample for 2 hour periods in the test solution maintained  at 60 ± 2 °C. Retain a duplicate 
piece of tableware with each decoration under test without exposure to the solution as an aid in judging the 
degree of chemical action on the specimens under test. At the end of the 2 hour periods, remove the specimens 
from the solution, rub vigorously with a cloth under running water, dry and evaluate.  
C.3.2 Grade the decorations after 2 -hour period of immersion in accordance with one of the following classes;  
Class 1 -No loss of gloss . 
                  Class 2 - gloss  loss, No loss of opacity.  
       Class 3 -Noticeable loss opacity.  
                   Class 4-Complete removal of decoration  
C.3.3  The glass passes the test i f there is no attack apparent on the decoration that  shall be of Class 1  or 2. 
 
 
 
 
 
 
 
 
  
7 
 Bibliography  
KS 513:1985  Specification for glass tableware .