PUBLIC REVIEW DRAFT DRAFT UGANDA STANDARD  
  DUS 
1976:2018  
First Edition  
2018 -mm-dd 
 
 
 Reference number  
DUS 1976 : 2018  
© UNBS 2018   
  
Road Marking glass spheres (beads) — Specification 
 PUBLIC REVIEW DRAFTDUS 1976: 2018 
ii © UNBS 2018  – All rights reserved  
 Compliance with this standard does not, of itself confer immunity from legal obligations  
A Uganda Standard does not purport to include all necessary provisions of a contract. Users are 
responsible for its correct application  
© UNBS 2018  
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilised in any 
form or by any means, electronic or mechanical, including photocopying and microfilm, without prior writte n 
permission from UNBS. 
Requests for permission to reproduce this document should be addressed to 
The Executive Director 
Uganda National Bureau of Standards 
P.O. Box 6329 
Kampala 
Uganda 
Tel: +256 414 333 250 /1/2/3 
Fax: +256 414 286 123 
E-mail: info@unbs.go.ug  
Web: www.unbs.go.ug  
 PUBLIC REVIEW DRAFTDUS 1976: 2018 
© UNBS 2018  – All rights reserved  iii 
 Foreword 
Uganda National Bureau of Standards (UNBS) is a parastatal under the Ministry of Trade, Industry and 
Cooperatives established under Cap 327, of the Laws of Uganda, as amended.  UNBS is mandated to co-
ordinate the elaboration of standards and is  
(a) a member of International Organisation for Standardisation (ISO) and  
(b) a contact point for the WHO/FAO Codex Alimentarius Commission on Food Standards, and  
(c) the National Enquiry Point on TBT Agreement of the World Trade Organisation (WTO). 
The work of preparing Uganda Standards is carried out through Technical Committees. A Technical 
Committee is established to deliberate on standards in a given field or area and consists of key stakeholders 
including government, academia, consumer groups, private sector and other interested parties.  
Draft Uganda Standards adopted by the Technical Committee are widely circulated to stakeholders and the 
general public for comments. The committee reviews the comments before recommending the draft standards 
for approval and declaration as Uganda Standards by the National Standards Council. 
The committee responsible for this document is Technical Committee UNBS/TC5/SC2, Paints, Varnishes and 
related products. PUBLIC REVIEW DRAFTDUS 1976: 2018 
iv © UNBS 2018  – All rights reserved  
 Introduction 
Reflective glass beads (also called glass spheres) are often added to traffic paint to enhance safety because 
they enable drivers to see traffic lanes more clearly, especially at night and in wet weather. The glass beads 
may be pre-mixed with the traffic paint or applied separately as the striping paint is being applied to the road, 
curb or other surface. Either way, glass beads are almost always specified separately from traffic paint on 
which they are applied.  
Moreover, their ability to reflect light (retroreflectivity) and durability – two key technical requirements – need to 
be addressed in the specifications because glass beads vary based on their size, roundness, color, clarity, 
refractive index, and other factors. Variations in sizes and types of glass beads are matched for compatibility 
with paints used for different traffic marking needs including waterborne and solvent-based traffic-and zone-
marking applications 
 
 PUBLIC REVIEW DRAFTWORKING DRAFT UGAND A STANDARD  DUS 1976 : 2018  
 
© UNBS 2018  – All rights reserved  1 
 Road Marking glass spheres (beads) — Specification 
1 Scope  
This draft Uganda standard specifies requirements and methods of test and sampling for glass beads to be 
dropped or sprayed upon pavement markings so as to produce a reflectorized pavement marking. 
2 Normative references 
DUS 2008; Standard Test Method for Sieve Analysis of Glass Spheres 
DUS 2009; Standard Test Method for Roundness of Glass Spheres 
DUS 2010; Test Method for Crushing Resistance of Glass Spheres 
 
3 Terms and definitions  
For the purposes of this standard, the following terms and definitions shall apply  
ISO and IEC maintain terminological databases for use in standardization at the following addresses:  
— ISO Online browsing platform: available at http://www.iso.org/obp  
4 General Requirements  
4.1 Types: 
Road marking glass beads should be one of the following type s. 
a) Type 1 – shall be known as a standard gradation. 
b) Type 2 – shall be known as uniform gradation. 
4.2 Flotation 
Either of the above gradation types may be obtained with flotation properties at the request of the purchaser. 
4.3 Moisture Resistance  
Either of the above types may be obtained with a moisture-resistance coating if so specified by the purchaser. 
Note: 1 Since the flotation coating imparts moisture resistance to the beads the moisture resistance test may be 
waived by the purchaser if the beads are ordered with the flotation property. 
4.4 Appearance 
The beads shall be transparent, clean, colorless glass, smooth and spherically shaped, free from milkiness, 
pits, or excessive air bubbles and conform to the following specific requirements. PUBLIC REVIEW DRAFT 
2 © UNBS 2018  – All rights reserved  
 5 Specific Requirements 
5.1 Gradation 
The beads shall meet the gradation requirements for type as given in Table 1. 
5.2 Roundness 
The glass beads shall have a minimum of seventy percent (70%) true spheres. 
5.3 Crushing Resistance – Retained 0.425-mm (No. 40) sieve 133 N (30lbs.) minimum. 
5.4 Refractive Index – The glass beads shall have a minimum refractive index of 1.5. 
5.5 Moisture Resistance – Flow characteristics – The beads shall not absorb moisture in storage. 
They shall remain free of clusters and lumps and shall flow free from dispensing equipment. 
5.6 Flotation – When tested in accordance with Annex B, a minimum of 90-percent beads shall float in 
xylene. 
 
TABLE 1 Gradation of Road marking Glass Beads 
Sieve Designation  Mass Percent Passing  
Standard mm  Alternate  No. Type 1  Type 11  
0.850  20 100 — 
0.600  30 75 — 95 100 
0.425  40 — 90 — 100 
0.300  50 15 — 35 50 — 75 
0.180  80 — 0 — 5 
0.150  100 0 — 5 — 
 
 
 
4. Methods of Sampling and Testing 
4.1 The sampling shall be random in the following ratios – 45 kg (100 lbs) of sample (in full bags) per 
4535kg (10000 lbs.) shipped. Upon arrival material shall be reduced in a sample splitter to a size of 
approximately 1-kg. 
4.2 The following requirements shall be tested with the following test methods: 
Gradation – DUS 2008 
Roundness – DUS 2009 
Crushing – DUS 2010 
4.3 The refractive index shall be tested by liquid immersion method ASTM C 1648-12 (Becke Line Method 
or equal ) - at a temperature of 25 +/- 5 deg. C (77 +/- 9 deg. F) PUBLIC REVIEW DRAFTDUS 1976 : 2018  
© UNBS 2018  – All rights reserved  3 
 4.4 Flow Characteristics 
Beads will flow properly when tested in accordance with Annex A procedure (a) unless they are specified to 
be moisture resistant, in which case, testing in accordance with Annex A procedure (b). 
 
4.5 Flotation Test 
Beads should pass the flotation test when tested in accordance to Annex B. 
5. Packaging and Labelling 
5.1 Packaging 
Glass beads shall be furnished in 1-kg (lbs.) lots as specified by the purchaser and packaged in moisture-
proofed bags. Containers are to be guaranteed to furnish dry and undamaged beads. 
5.2 Labe ling 
Each package shall contain the following information: 
a) Name and address of manufacturer,  
b) shipping point,  
c) trademark or name, the wording “glass  beads”,  
d) the specification number,  
e) number of kg ,  
f) the lot or batch number and  
g) the month and year of manufacture. 
 PUBLIC REVIEW DRAFT 
4 © UNBS 2018  – All rights reserved  
 Annex A 
(normative)  
 
Flow Characteristics  
A.1 Procedure (b) 
A 100-g sample of beads is placed in a Corning 3140 crystallizing dish. 100-mm diameter by 50-mm depth. 
Place the dish in a Corning 3080 Dessicator (or equivalent) 250-mm inside diameter by 330- mm o verall height 
and 130-mm chamber depth, which shall be filled with a sulfuric acid-water solution having a specific gravity of 
1.10 (approximately 94 percent humidity) to a point 25.4-mm below the top of a size 5 Coors 60003 
Dessicator Plate. The sample shall remain in the covered Dessicator at 25 ± 5 deg. C for four (4) hours. 
Remove the sample from the Dessicator and transfer the beads to a metal pan. The beads shall be essentially 
free of lumps and clusters and shall flow without stoppage when poured slowly through a standard glass 
funnel (Corning 6120), 126-mm diameter, 102-mm stern length, and 11-mm stern inside diameter (Note 1). 
A.1 Procedure (b) 
A 100-g sample of beads is placed in a 600-ml beaker and an equivalent volume of distilled water shall be 
added to the beaker. The beaker will then stand for five (5) minutes, at the end of which time the water shall 
be carefully poured off and the beads transferred to a clean, dry, beaker and allowed to stand for five (5) 
minutes. 
The beads will then be poured slowly into a standard glass funnel (Corning 6120), 127-mm diameter, 102- mm 
stem length, and 11-mm stem inside diameter. The beads shall flow through the funnel at the beginning of the 
test is permissible. 
 PUBLIC REVIEW DRAFTDUS 1976 : 2018  
© UNBS 2018  – All rights reserved  5 
 Annex B 
(normative) 
 
Flotation Test  
B.1 Procedu re 
Determine the mass of approximately 1-g to the nearest 0.005-g; evenly distribute beads into a clean standard 
100-mm glass Petri dish previously weighted to the nearest 0.0005-g. The dish is vibrated slightly to attain the 
near as possible a monolayer of beads. Xylene, C.P. Grade is introduced at one side of the dish at a rate of 
10 to 15 mL per minute from a burette until 30 mL has been added. The floating beads are then carefully 
drawn off by suction through a suitably constricted delivery tube connected to a receiving flask. Excess is 
drawn off so that no remaining beads are lost and the dish dried in an oven at 110 ± 5 deg. C. The dish is 
weighed and the percentage of floating beads calculated. 
 PUBLIC REVIEW DRAFT 
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 Bibliography 
 
 PUBLIC REVIEW DRAFTDUS 1976: 2018 
© UNBS 2018  – All rights reserved  7 
 Certification marking 
Products that conform to Uganda standards may be marked with Uganda National Bureau of Standards 
(UNBS) Certification Mark shown in the figure below.  
The use of the UNBS Certification Mark is governed by the Standards Act, and the Regulations made 
thereunder. This mark can be used only by those licensed under the certification mark scheme operated by 
the Uganda National Bureau of Standards and in conjunction with the relevant Uganda Standard. The 
presence of this mark on a product or in relation to a product is an assurance that the goods comply with the 
requirements of that standard under a system of supervision, control and testing in accordance with the 
certification mark scheme of the Uganda National Bureau of Standards. UNBS marked products are 
continually checked by UNBS for conformity to that standard.  
Further particulars of the terms and conditions of licensing may be obtained from the Director, Uganda 
National Bureau of Standards.  
 
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