ICS 81.060.20  
 
Reference number  
RS 432: 2019  
© RSB 2019  
  
 RWANDA 
STANDARD  DRS 
432  
 
First edition  
2019 -mm-dd 
 
Handmade ceramic products  — 
Specification  
   
DRS 432: 2019  
©RSB 2019 - All rights reserved                  ii 
 In order to match with technological development and to keep continuous progress in industries, 
standards are subject to periodic review. Users shall ascertain that they are in possession of the latest 
edition   
 
 
 
 
 
 
 
 
© RSB 2019  
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized 
in any form or by any means, electronic or mechanical, including photocopying and microfilm, without 
prior written permission from R SB. 
Requests for permission to reprodu ce this document should be addressed to : 
Rwanda Standards  Board  
P.O Box 7099 Kigali -Rwanda  
KK 15 Rd, 49  
Tel. +250 788303492  
Toll Free: 3250  
E-mail: info@rsb.gov.rw  
Website: www.rsb.gov.rw  
ePortal: www.portal.rsb.gov.rw   DRS 432: 2019  
iii                ©RSB 2019  - All rights reserved  
 Contents  Page 
Foreword  ................................ ................................ ................................ ................................ ...................  iv 
1 Scope  ................................ ................................ ................................ ................................ .............  1 
2 Normative references  ................................ ................................ ................................ ...................  1 
3 Terms and definitions  ................................ ................................ ................................ ..................  1 
4 Requirements  ................................ ................................ ................................ ................................  2 
4.1 General requirements  ................................ ................................ ................................ ..................  2 
4.1.1  Categories  ................................ ................................ ................................ ................................ ..... 2 
4.1.2  Usability  ................................ ................................ ................................ ................................ .........  2 
4.1.3  Safety  ................................ ................................ ................................ ................................ .............  2 
4.1.4  Shattering  ................................ ................................ ................................ ................................ ...... 3 
4.1.5  Raw materials  ................................ ................................ ................................ ...............................  3 
4.1.6  Manufacturing  ................................ ................................ ................................ ...............................  3 
4.1.7  Workmans hip ................................ ................................ ................................ ................................  3 
4.1.8  Surface finish for category I ceramic product  ................................ ................................ ...........  3 
4.2 Specific requirements  ................................ ................................ ................................ ..................  4 
4.2.1  Limits of contaminants  ................................ ................................ ................................ ................  4 
4.2.2  Specific physical requirements for category II ceramic products  ................................ ..........  4 
4.2.3  Finish  ................................ ................................ ................................ ................................ .............  4 
4.2.4  Decoration  ................................ ................................ ................................ ................................ ..... 4 
4.2.5  Warpage  ................................ ................................ ................................ ................................ ........  4 
4.2.6  Porosity  ................................ ................................ ................................ ................................ .........  5 
5 Sampling  ................................ ................................ ................................ ................................ ....... 5 
6 Dimensions  ................................ ................................ ................................ ................................ ... 5 
7 Packaging  ................................ ................................ ................................ ................................ ...... 5 
8 Labelling  ................................ ................................ ................................ ................................ ........  5 
8.1 Labelling of ceram ic product(s)  ................................ ................................ ................................ .. 5 
Annex  A (normative)  Test Methods  ................................ ................................ ................................ ........  6 
A.1 Warpages  ................................ ................................ ................................ ................................ ...... 6 
A.1.1  Out-of-roundness  ................................ ................................ ................................ .........................  6 
A.1.2  Edge w arpage and slope for flatware  ................................ ................................ .........................  6 
A.2 Porosity  ................................ ................................ ................................ ................................ .........  6 
A.2.1  Test ................................ ................................ ................................ ................................ ................  6 
A.2.2  Procedure  ................................ ................................ ................................ ................................ ...... 6 
A.2.3  Calculation  ................................ ................................ ................................ ................................ .... 7 
 DRS 432: 2019  
©RSB 2019 - All rights reserved                  iv 
 Foreword   
Rwanda Standards are prepared by Technical Committees and approved by Rwanda Standards Board (RSB) 
Board of Directors in accordance with the procedures of RSB, in compliance with Annex 3 of the WTO/TBT 
agreement on the preparation, adoption and application of sta ndards.  
The main task of technical committees is to prepare national standards. Final Draft Rwanda Standards adopted 
by Technical committees are ratified by members of RSB Board of Directors for publication and gazettement as 
Rwanda Standards.  
DRS 432 was prepared by Technical Committee RSB/TC 25, Handcrafts products . 
In the preparation of this standard, reference was made to the following standard (s):  
1) ISO 8391 -2:1986 Ceramic cookware in contact with food -- Release of lead and cadmium -- Part 2: 
Permissi ble limits  
2) IS 14179 : Methods of test for ceramic tableware  
3) IS 2838:  Specification for stoneware containers for general purposes  
4) IS 6988:2002 Fine (Bone) China Crockeryware — Specification (second revision)  
The assistance derived from the above source is h ereby acknowledged with thanks.  
Committee membership  
The following organizations were represented on the Technical Committee on Handcrafts products (RSB/TC 
25) in the preparation of this standard.  
Ministry of Trade and Industry (MINICOM)  
Poterie de Gatagara  
Uburiza Arts Ltd  
JNM Company Ltd  
City of Kigali  ̶  Agaseke Project  
Glo-Creations Ltd  
Rwanda  Standards Board  (RSB) – Secretariat  DRS 432: 2019  
v                ©RSB 2019  - All rights reserved  
 Introduction   
Ceramic products are useful in the daily life of human beings and they have various uses such as decora tion, 
cooking and sanitary use. They are also used as structural materials such as interior refractory/kiln linings, steel 
and glass making crucibles. In Rwanda, ceramic products, especially handmade, are still locally made. It is in 
this regard, that a st andard which specifies requirements, methods of sampling and test was developed.  
 DRS 432: 2019  
1                ©RSB 2019  - All rights reserved  
 Handmade ceramic products  — Specification  
1 Scope   
This Draft Rwanda Standard specifies requirements, sampling and test methods for ceramic products. It may 
be applied to ceramic products   manufactured using machine(s).  
This Draft Rwanda Standard is not applicable to other ceramic pr oducts which have standards specific to them 
including but not limited to glasses, bricks, tiles.  
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 doc ument.  For dated references, only the edition cited applies. For undated references, the 
latest edition of the referenced document (including any amendments) applies.  
ISO 8391 -1Ceramic cookware in contact with food -- Release of lead and cadmium -- Part 1:  Method of test  
3 Terms and definitions   
For the purposes of this standard, the following terms and definitions apply.  
3.1 
ceramic product  
inorganic non -metallic item made from clay and hardened by heat  
3.2  
handmade  
made  skilfully using hands from raw materials  
Note 1 to entry  Finishing may be done using tools or machines.  
3.3 
raw materials  
basic materials such as clay or any other materials used to make a ceramic product   
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 3.4 
lot 
All items of same shape, size, decoration and materials of manufacture and which belong to the same batch of 
manufacture  
3.5 
warpage  
out of roundness or shape or deviation from shape or roundness  
3.6 
foodware  
ceramic ware used in the preparation, cooking, serving or storage of food and beverages  
4 Requirements  
4.1 General requirements  
4.1.1  Categories  
Any ceramic product shall fall into one of the two categories in Table 1. 
Table 1 — Categories of ceramic products  
Category  Intended application  
Category I ceramic products  Ceramic products whose use lead them to 
contact with foodstuffs  
Category II ceramic products  Ceramic product whose use is not intended 
for foodstuffs  
NOTE 1  An example of category I ceramic products is foodware.  
NOTE 2  Ceramic tables are in category I ceramic products.  
4.1.2  Usability  
Manufacturer shall ensure that the ceramic product is user -friendly.  
NOTE 6  An example of a user -friendly ceramic product is easy to  grab and transport.  
4.1.3  Safety  
Ceramic product shall not contain any harmful product to the environment whether during service or disposal.  DRS 432: 2019  
3                ©RSB 2019  - All rights reserved  
 4.1.4  Shattering  
Ceramic product shall not shatter upon grabbing  
4.1.5  Raw materials  
Raw materials shall be essentially ceramic mat erials. Additional materials can be used to improve properties of 
the intended product.  
Raw materials, for category I ceramics products, shall not result, directly or indirectly, in becoming a component 
of food, or otherwise affecting the characteristics o f food, including the imparting of a colour, taste, or odour to 
food;  
NOTE 3  An example of ceramic material: clay.  
4.1.6  Manufacturing  
4.1.6.1  Manufacturer shall use his/her hands to shape the product. Finishing may be done by hands or 
equipment.  
4.1.6.2  A ceramic product shall be free from deleterious substances, flaws and other manufacturing defects 
which might affect their intended utility.  
4.1.6.3  A ceramic product shall be sound and true to shape and heat maybe used to optimize the properties 
of the pro duct.  
4.1.6.4  Modifiers shall be used so as to achieve intended product properties.  
4.1.6.5  With agreement between the manufacturer and the customer, the heat treatment temperature shall be 
specified to ensure mechanical properties are optimized.   
4.1.7  Workman ship 
4.1.7.1   Ceramic items in one batch shall be of the same shape.  
4.1.7.2  Where items have lids, they shall be so designed to hold liquids as intended and shall fit properly.  
4.1.8  Surface finish for category I ceramic product  
The side which comes in contact with foodstuffs shall have a smooth surface finish  and shall be free from any 
defects which would affect its intended use.   
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 4.2 Specific requirements  
4.2.1  Limits of contaminants  
When tested in accordance with test method specified in Table  2, category I ceramic products shall meet the 
limits as specified below.  
Table 2 — Maximum permissible levels of contaminants in category I ceramic products  
Contaminants  Maximu m permissible levels  
mg/l Test Method  
Lead  5  ISO 8391 -1 
Cadmium  0.5  ISO 8391 -1 
 
4.2.2  Specific physical requirements for category II ceramic products  
4.2.2.1 Specific physical requirements for items, which fall in category II ceramic products, shall be agreed 
upon between the customer and the manufacturer.  
4.2.3  Finish  
The surface of the ceramic product shall be as free as possible from any visual defects and shall be impervious 
to water.  
Paint and other organic coatings can be used on surfaces of ceramics pro ducts. However, only food grade 
paints and coatings shall be used for the products intended for contact with foodstuff.  
4.2.4  Decoration  
Decoration shall be done in accordance with agreement between the manufacturer and the customer.  
4.2.5  Warpage  
Warpage shall be det ermined in accordance with Annex A and shall meet the permissible limits specified in 
Table 3. 
Table 3 — Permissible limits for warpage  
Parameter  Out-of-roundness 
(limit,  %) Edge warpage 
(mm)  Slope (degree, o) 
Permissible limit value  0.8 1.5 1.5 
 DRS 432: 2019  
5                ©RSB 2019  - All rights reserved  
 4.2.6  Porosity  
4.2.5 .1 Porosity of a ceramic product is indicated by the amount of water absorbed.  
4.2.5 .2 When tested in accordance with Annex A, water absorption shall not exceed 3  % for glazed 
products and 6 % for unglazed products.  
5 Sampling  
5.1 When sampling for clause 4.2.5 (limits of contaminants), four items shall be sampled. For other tests, 
three items shall be sampled.  
5.2 Each of the items shall be identical in size and sha pe. 
6 Dimensions  
The dimensions shall be subject to a tolerance of ± 0.5 %. For ceramic products where volume is important, a 
volume tolerance of ± 2.5 % shall apply.  
NOTE 7  An example of a ceramic product where volume is important is cups  
7 Packaging  
Ceramic products shall be packaged in suitable materials that prevent damage during normal handling, storage 
and transportation. Otherwise, the packaging shall be as agreed upon between the purchaser and the 
manufacturer.  
8 Labelling  
8.1 Labelling of ceramic product(s)  
Both bulk package and ceramic product(s) shall be legibly and indelibly labelled with, at least, the following 
information:  
a) Manufacturer’s/supplier’s name, trade mark or both;  
b) batch and lot number  
c) dimension(s)/volume of the  packaged ceramic product(s)  
d) country of origin/ manufacture  
NOTE 1  Labelling can also be done by embossing or inscribing the item to be labelled.  
NOTE 2  Where items of different dimensions or volume are in one bulk package, a range of dimensions or volumes of 
packaged items can be labell ed accordingly.   
©RSB 2019 - All rights reserved                  6 
 Annex  A 
(normative)  
 
Test Methods  
A.1 Warpages  
A.1.1  Out-of-roundness  
A dial indicator shall be used to determine the out -of-roundness of a ceramic product. The sample, resting on 
its foot on a flat surface, shall be blocked in a manner to allow its rotatio n. The indicator plunger shall strike the 
outer rim edge of the sample from above at a 450 angle to a horizontal plane. The sample shall be rotated and 
the low and high readings shall be taken. The difference between the two readings shall denote the out -of-
roundness.  
A.1.2  Edge warpage and slope for flatware  
Edge warpage and slope of items shall be determined as follows:  
a) Invert the sample and place it face down on a surface plate,  
b) Place a weight across the resting surface of the item to stabilize it in place,  
c) Attempt to insert a feeler gauge between the surface and any portion of the sample edge. The readings 
of the feeler gauge will indicate the warpage on the edge of the item.  
d) Remove the weight from the resting surface and replace it with an inclinometer,  
e) Determine the slope of the resting surface.  
A.2 Porosity  
A.2.1  Test 
Three test pieces, each having a surface area of about 50cm2 shall be broken from widely separated parts of 
three or more articles. The surfaces shall be freshly broken and care shall be taken not t o produce cracks in the 
body of the test pieces. If any cracks are developed, such pieces shall be discarded.  
A.2.2  Procedure  
Dry the test pieces to a constant weight at a temperature between 1100C and 1150C and then cool to room 
temperature in a desiccator. Wei ght the pieces to an accuracy of not less than 0.01g and place in a vessel from 
which the air can be removed maintaining the pressure at less than 3cm of mercury for one hour. Admit cold 
freshly -boiled distilled water to the vessel without reducing the vac uum until the pieces are covered. Then, admit 
air to the vessel without removing the pieces and boil in a smooth cloth in such a manner as to remove the 
surface water only and then weigh quickly.  
 DRS 432: 2019  
7                ©RSB 2019  - All rights reserved  
 A.2.3  Calculation  
A.2.3.1  Water absorption of the test pieces shall be ca lculated as follows:  
percentage water absorption = 𝑊2−𝑊1
𝑊1𝑥100 
where 𝑊1= weight of the dry testpiece, and  
      𝑊2 = weight of the testpiece after treatment  
A.2.3.2  All the six test pieces shall show a water absorption as specified in clause 4.2.11.  
   
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 Bibliography  
[1] [1] ISO 13006:2018 Ceramic tiles -- Definitions, classification, characteristics and marking  
[2]  ISO 10545 -3:2018 Ceramic tiles -- Part 3: Determination of water absorption, apparent porosity, apparent 
relative density and bulk density  
[3]  IS 9806:2001 Methods of test for and permissible limits of toxic materials released from ceramic ware, 
vitreous enamelware, glassware and glass -ceramic ware in contact with food  
 
 DRS 432: 2019  
 
Price based on 7 pages  
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