ICS 87.040  
 
Reference number  
DRS 479: 2021  
© RSB 2021  
  
 RWANDA 
STANDARD  DRS  
479 
 
First edition  
2021 -mm-dd 
 
Two-pack Polyurethane full g loss enamel 
paint— Specification  
   
DRS 479: 2021  
©RSB 2021 - 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 2021  
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 479: 2021  
iii                ©RSB 2021 - All rights reserved  
 Contents  Page 
1 Scope  ................................ ................................ ................................ ................................ ......................  1 
2 Normative references  ................................ ................................ ................................ ............................  1 
3 Terms and definitions  ................................ ................................ ................................ ...........................  2 
4 Requirem ents ................................ ................................ ................................ ................................ ....... 32 
4.1 General requirements  ................................ ................................ ................................ .........................  32 
4.2 Specific requirements  ................................ ................................ ................................ ...........................  3 
5 Packaging and labelling ................................ ................................ ................................ ........................  4 
5.1 Packaging  ................................ ................................ ................................ ................................ ...............  4 
5.2 Labelling  ................................ ................................ ................................ ................................ .................  4 
6 Sampling  ................................ ................................ ................................ ................................ ................  5 
Annex  A (normative)  Method of identifying aromatic and aliphatic isocyanates  ................................ ....... 6 
A.1 General  ................................ ................................ ................................ ................................ ...................  6 
A.2 Reagents  ................................ ................................ ................................ ................................ ................  6 
A.3 Procedure  ................................ ................................ ................................ ................................ ...............  6 
Annex  B (normative)  Determination of finish  ................................ ................................ ................................ . 7 
B.1 Scope  ................................ ................................ ................................ ................................ ......................  7 
B.2 Procedure  ................................ ................................ ................................ ................................ ...............  7 
Annex  C (normative)  Determination of mass per 10 litres of liquid paint  ................................ ...................  8 
C.1 Scope  ................................ ................................ ................................ ................................ ......................  8 
C.2 Apparatus  ................................ ................................ ................................ ................................ ...............  8 
C.3 Procedure  ................................ ................................ ................................ ................................ ...............  9 
C.4 Calculations  ................................ ................................ ................................ ................................ ...........  9 
Annex  D (normative )  Accelerated tests  ................................ ................................ ................................ ........  11 
D.1 General  ................................ ................................ ................................ ................................ .................  11 
D.2 Procedure  ................................ ................................ ................................ ................................ .............  11 
Annex  E (normative)  Durability tests  ................................ ................................ ................................ ............  12 
E.1 General  ................................ ................................ ................................ ................................ .................  12 
E.2 Normal outdoor exposure test  ................................ ................................ ................................ ...........  12 
E.3 Accelerated weathering test  ................................ ................................ ................................ ...............  12 
Annex  F (normative)  Keeping properties tests  ................................ ................................ ............................  13 
F.1 Scope  ................................ ................................ ................................ ................................ ....................  13 
F.2 Apparatus  ................................ ................................ ................................ ................................ .............  13 
F.3 Procedure  ................................ ................................ ................................ ................................ .............  13 
 DRS 479: 2021  
©RSB 2021 - All rights reserved                  iv 
 Foreword  
Rwanda Standard s are prepared  by Technical Committees and approved by R wanda 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 standards.  
The main task of technical committees is to prepare national standards.  Final Draft Rwanda S tandards 
adopted by Technical committ ees are ratified  by me mbers of RSB Board of Director s for publication and 
gazettment as Rwanda Standards.  
DRS 479  was prepared by Technical Committee RSB/TC 056, Paints, Varnishes, Adhesives and Related 
Products . 
In the preparation of this standard, reference was made to the following standard:  
IS 13213 : Polyurethane full gloss enamel (Two pack) — Specification  
The assistance de rived from the above source is hereby acknowledged with thanks.  
Committee membership  
The following organizations were represented on the Te chnical Committee on Paints, Varnishes, Adhesives 
and related Products  (RSB/TC 056) in the preparation of this standard.  
Star Construction and Consultancy Ltd  
Rwanda Inspectorate, Competition and Consumer Protection Authority (RICA)  
Standards for Sustainability  
Yong Rui Mei Investments Ltd  
AMACO Paints Ltd  
AMEKI Colour Ltd  
Rwanda Investigation Bureau (RIB)  
University of Rwanda/College of Sciences and Technology (UR/CST)  
University of Rwanda/College of Education (UR/CE)  
Rwanda Forensic Laboratory (R FL) DRS 479: 2021  
v                ©RSB 2021 - All rights reserved  
 ROMAN Paints Ltd  
SHALOM Paints Ltd  
EARTHENABLE  
Rwanda  Standards Board (RSB) – Secretariat  DRS 479: 2021  
©RSB 2021 - All rights reserved                  vi 
 Introduction  
A polyurethane paint  (PU paint) is a hard -wearing, highly -resistant coating used in industrial and architectural 
coating systems for steelwork, concrete, wood, and other substrates. It is a reaction polymer, a combination of 
a polyol resin and an isocyanate hardener or curing agent. Essentially, a polyurethane coating is a liquid 
plastic which dries to form a paint -like film on a substrate . The properties of a polyurethane can be 
manipulated by the types of isocyanates and polyols which are used to make it, and so it can be mod ified to 
suit a wide range of projects. Polyurethane paint provides durability, resistance to chemicals, water, abrasion, 
and temperature, as well as an attractive glossy finish.  
The product is intended to be used as a top coat in painting system for the p rotection of exterior of railway 
coaches, etc. involving wet and damp areas, high humidity, coastal, marine and industrial fall out. 
Polyurethane paints shall be suitable for use in those exterior applications where it is desirable to retain colour 
and glo ss for long periods of time in addition to providing excellent chemical and corrosion resistance.  It is 
primarily suitable for application by spraying (conventional air/airless). It may also be applied by brush for 
touching up small areas.  
 
 DRS 47 9: 2021  
1                ©RSB 2021 - All rights reserved  
 Two-pack Polyurethane full gloss enamel paint — Specification  
1 Scope  
This Draft  Rwanda Standard  prescribes requirements, sampling and test methods for a two -pack polyurethane 
full gloss enamel paint intended to be uses for the protection of exterior of railway coaches, diesel and electric 
locomotive against atmospheric corrosion . 
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 th e referenced document (including any amendments) applies.  
ISO 4618 , Paints and varnishes — Terms and Definitions  
ISO 2431 , Paints and varnishes — Determination of flow time by use of flow cups  
ISO 3668, Paints and varnishes — Visual comparison of colour of  paints  
ISO 9514, Paints and varnishes — Determination of the pot life of multicomponent coating systems — 
Preparation and conditioning of samples and guidelines for testing  
ISO 28199 -1, Paints and varnishes — Evaluation of properties of coating systems re lated to the spray 
application process — Part 1 : Vocabulary and preparation of test panels  
ISO 9117 -1, Paints and varnishes — Drying tests — Part 1: Determination f through -dry state and through -dry 
time 
ISO 9117 -3, Paints and varnishes — Drying tests — Part 3: Surface -drying test using ballotini  
ISO 2808 , Paints and varnishes — Determination of film thickness  
ISO 3251 , Paints , varnishes and  plastics  — Determination of non -volatile matter content  
ASTM F735 -17, Standard test method for abrasion resistance  of transparent plastics and coatings using the 
oscillating sand method  
ISO 17132 , Paints and varnishes — T-bend test  
ISO 1523 , Determination of flash point — Closed cup equilibrium method  
ISO 1524 , Paints, varnishes and printing inks — Determination of fi neness of grind   
©RSB 2021 - All rights reserved                  2 
 ISO 2813 , Paints and varnishes — Determination of gloss value at 20 °, 60° and 85 ° 
ISO 6503 , Paints and varnishes — Determination of  total lead — Flame atomic absorption spectrometric 
method  
ISO 3856 -6, Paints and varnishes — Determination of “soluble” metal content — Part 6: Determination of total 
chromium content of the liquid portion of the paint — Flame atomic absorption spectrometric method.  
RS OIML R 87, Quantity of product in pre -packages  
ISO 15528, Paints, varnishes an d raw materials for paints and varnishes — Sampling  
3 Terms and definitions  
For the purposes of this standard, the terms and definitions given in ISO 4618 and the following apply.  
3.1 
component  
a term used to describe each of two parts of the paint, which when mixed together form the pigmented 
polyurethane  paint.  
3.2 
paint  
the mixture of the two components in the proportion recommended by the manufacturer.  
3.3 
polyurethane paint  
a reaction polyme r, a combination of a polyol resin and an isocyanate hardener or curing agent.  
3.4 
two-pack /two components  
a term used to describe each of two parts of the paint, which when mixed together form the pigmented epoxy 
layer  
3.5 
enamel paint  
is loosely used to designate a shiny, glossy, decorative topcoat.  DRS 47 9: 2021  
3                ©RSB 2021 - All rights reserved  
 4 Requirements  
4.1 General requirements  
4.1.1  The paint shall consist essentially of two components : enamel and hardener or catalyst solution to be 
mixed in such simple proportion preferably by volume . 
4.1.2  An enamel shall consist of  
(i) an appropriate polyol, and  
(ii) pigments, extenders, solvents and additives.  
4.1.3  Hardener or catalyst solution shall consist of  
(i) an aliphatic polyisocyanate, and  
(ii) solvents and additives.  
NOTE  To determine whether the polyisocyanate is aliphatic or aromatic in nature, the test shall be carried out as 
prescribed in Annex A. 
4.1.4  The mixture of base and hardener shall be allowed to mature for 20 min. at 27 ± 2 °C. the mixture 
must be consumed wit hin 4 hours after mixing.  
4.1.5  The two component polyurethane finish enamel paint shall be mixed in the ratio recommended by the 
manufacturer of the paint before conducting the test or tests. Where the enamel is required to be applied on 
panels, it shall be done so by using suitable spraying apparatus.  
4.2 Specific requirements  
The product shall comply with the requirements given in Table 1 when tested in accordance with the methods 
prescribed therein.  
Table 1 – Specific requirements for two -pack polyurethane full gloss enamel  paint  
S/N Parameters  Requirements  Test methods  
1 Drying time, h, 
max.  Surface dry  3 ISO 9117 -1 
Hard dry  8 ISO 9117 -3 
2 Consistency  Smooth and uniform and 
suitable  for spray 
application  ISO 2431  
3 Finish  Smooth and full glossy  Annex B 
4 Colour  Close match to be 
specified IS O colour or to 
an agreed colour  ISO 3668  
5 Dry film thickness, µm, min.  35 ISO 2808  
6 Solids content , % by mass, min.  40 ISO 3251  
7 Scratch hardness  No such scratch as to ASTM F735 -17  
©RSB 2021 - All rights reserved                  4 
 show bare metal  
8 Flexibility and adhesion  No visible damage or 
detachment of film  ISO 17132  
9 Flash point (for each component), °C, min.  20 ISO 1523 
10 Fineness of grind, µm, max.  10 ISO 1524  
11 Pot life at 27 ± 2 °C, h, min.  4 ISO 9514  
12 Gloss at 45 ° angle of incidence, min.  52 ISO 2813  
13 Mass in kg/10 L, min.  9 Annex C  
14 Accelerated tests  Resistance to sulphuric 
acid Shall not show any signs 
of blistering, wrinkling 
and lifting. Difference in 
gloss and colour between 
immersed and un -
immersed area  of paint 
film shall be minimum  Annex D 
Resistance to caustic 
potash  Do 
Resistance to oil  Do 
Resistance to solvents  Do 
15 Durability test  Outdoor exposure  Chalking 10  
Annex E Accelerated weathering  - Checking 10  
- Cracking 10  
- Flaking 10  
- Spotting 10  
- Blistering 10  
- Colour change 7 – 8 
- Gloss – the film shall 
have a minimum gloss 
retention of 90% of its 
original value  
- No corrosion  
16 Keeping properties  Not less than 1 year  Annex F  
17 Total lead content, mg/kg, max.  90 ISO 6503  
18 Chromium content, mg/kg in dried paints, 
max.  5 ISO 3856 -6 
5 Packaging and labelling  
5.1 Packaging  
5.1.1  The paint  shall be packaged in a suitable container that prevents it from deterioration during storage, 
transportation and normal handling.  
5.1.2  The quantity of product packaged in a container shall be in accordance with the requirements of RS 
OIML R 87.  
5.2 Labelling  
5.2.1  Each container shall be marked legibly and indelibly with the following:  
a) name of the product as:  “Two-pack polyurethane full gloss enamel paint ”; DRS 47 9: 2021  
5                ©RSB 2021 - All rights reserved  
 b) name and address of the manufacturer and/or registered trader mark;  
c) net content ; 
d) manufacture  and expiry dates ; 
e) spreading capacity, in m2/L; 
f) instructions for use and disposal;  
g) pot-life life at 25 0C; 
h) an indication of flammability.  
i) storage condition  
5.2.2  Each label of the container shall be marked legibly and indelibly with the following:  
a) manufacture  and expiry dates ; 
b) Instructions for use;  
c) Pot-life; 
d) Colour;  
e) Batch number.  
6 Sampling  
Sampling shall be done in accordance with ISO 15528.  
  
©RSB 2021 - All rights reserved                  6 
 Annex  A 
(normative)  
 
Method of identifying aromatic and aliphatic isocyanates  
A.1 General  
Aliphatic polyisocyanates show no colouration while aromatic polyisocyanates show a light brown to a dark 
reddish brown colouration with hydrogen peroxide.  
A.2 Reagents  
A.1.1  Acetone  
A.1.2  Hydrogen peroxide  solution (3%) in acetone  
A.3 Procedure  
A.3.1  Prepare an approximately 40 – 50 % solution of the polyisocyanate in acetone. To 50 ml of this 
solution, stir 1 ml of 3 percent hydrogen peroxide solution. Allow it to stand for 5 – 10 min.  
A.3.2  The development of any light brown to a dark reddish brown colour indicates aromatic 
polyisocyanates. No colour indicates aliphatic polyisocyanates.  
  DRS 47 9: 2021  
7                ©RSB 2021 - All rights reserved  
 Annex  B 
(normative)  
 
Determination of finish  
B.1 Scope  
This test method prescribes the details for determinat ion of finish of paint and varnish films.  
B.2 Procedure  
The pant when applied on a mild steel panel by brushing or spraying, whichever is specified, to give a dry film 
mass commensurate with the mass per 10 litres of the paint as given in table B1 and allowed to dry in a 
vertical position under specified conditions in dust free atmosphere, shall dry to a hard, firmly adherent, 
flexible and smooth film, free from sagging and wrinkling, with a matt semi -glossy or glossy surface in 
accordance with the requirements  of the paint specification.  
Table B1 – relationship between dry film mass of single coat of paint material and mass per 10 litres of 
the paint material  
Mass of the paint material in kg/10L  Dry film mass, g/m2 
Up to and including 10  17 to 22  
Above 10 to 11 22 to 27  
Above 11 to 12  27 to 34  
Above 12 to 14  34 to 44  
Above 14 to 16  44 to 54  
Above 16 to 18  54 to 68  
Above 18  68 to 80  
The film so produced shall be of normal opacity and in no way inferior to a film prepared in the same manner 
and at the same  time from approver sample, when examined not earlier than 48 hours and not later than 100 
hours after application. In case of failure, the test shall be repeated by keeping the painted panels under 
standard atmospheric conditions.   
©RSB 2021 - All rights reserved                  8 
 Annex  C 
(normative)  
 
Determinat ion of mass per 10 litres of liquid paint  
C.1 Scope  
This test method prescribes the determination of mass per 10litres of liquid paints and related products by 
pyknometer or a mass per volume cup.  
C.2 Apparatus  
Pyknometer – of capacity 20 to 10 ml as showed in fig ure 1, 2 and 3  
 
Thermometer – Graduated in divisions of 0.1 °C and accurate to 0.2 °C. 
DRS 47 9: 2021  
9                ©RSB 2021 - All rights reserved  
 Water -bath of constant temperature room – capable of being maintained with ± 2 °C. 
Analytical balance – accurate to 0.2 mg  
C.3 Procedure  
C.3.1  Clean the pyknometer suitably  (see note 1) . Thoroughly dry the pyknometer. Allow the pyknometer to 
attain room temperature and weight it. Fill the pyknometer with distilled water at a temperature not more than 
1 °C below the standard temperature (27 ± 2 °C). Stopper or cap the pyknometer leaving the overflow orifice 
open. Every care shall be taken to prevent the formation of bubbles in the pyknometer. Place the pyknometer 
in the constant temperature water -bath or place it in the constant temperature room  until the temperature of  
the pyknometer and its contents in constant. Remove the overflow by wiping with absorbent material (see note 
2) and thoroughly dry the outside of the pyknometer by wiping with absorbent material. Do not remove any 
subsequent overflow (see note 3). Immedia tely weigh the filled apparatus to the nearest 0.0001 % of its mass 
(see note 4).  
NOTE 1  If it is a glass pyknometer, use chromic acid, distilled water and a solvent. If it is a metal pyknometer, use 
solvent which leaves no residue on evaporation.  
NOTE 2  A paper tissue is recommended for this purpose.  
NOTE 3  Handling the pyknometer with bare hands will increase the temperature and cause more overflow from the 
overflow orifice and will also leave finger prints, hence, handling only with tongs and with hands protected by clean, dry 
absorbent material is recommended.  
NOTE 4  Immediate and rapid weighning of the filled pyknometer is recommended in ordre to minimize loss in mass 
due to evaporation and overflow subsequent to the first wiping after attainment of tem perature . 
C.3.2  Repeat the above procedure using the product in place of distilled water. Remove any residues of 
paint from the outside of the pyknometer by wiping with absorbent material moistened with a suitable solvent 
and thoroughly dry by wiping with a clean absorbent material.  
C.3.3  When using glass pyknometers with pigmented products, difficulties may be experienced in removing 
residual pigments, especially from ground -glass surfaces. Such residues may be removed by ultrasonic 
vibration in a water or  solvent bath.to minimize errors, joints shall be firmly seated. For accurate 
determination, glass pyknometers are preferred. Metal pyknometers are generally used for determination of 
mass in kg/10litres for production control purposes. If the sample retai ns air bubbles, which do not readily 
disperse on standing, the methods described in this standard are unsuitable.  
C.4 Calculations  
C.4.1  Calculation of volume of the pynometer  – calculate the volume of pyknometer in millilitres as 
follows:  
         V=𝑚1−𝑚0
𝑑 
Where,   
©RSB 2021 - All rights reserved                  10 
    V = volume in ml of pyknometer;  
   m1 = mass in g of pyknometer and water;  
   m0 = mass in g of the empty pyknometer, and  
   d = density of water at 27 °C in g/ml (0.996 5 g/ml)  
C.4.2  Calculation of density  – Calculate the density of the product in g/ml at the test temperature (27 °C) 
by the following formula:  
          𝑑𝑡=𝑚2−𝑚0
𝑉 
Where,  
   dt = density of the product at test temperature (27 °C); 
   m2 = mass in g of the pyknometer and product;  
   m0 = mass in g of empty pyknometer; and  
   V = volume in ml of the pyknometer at 27 °C 
C.4.3  Calculation of mass in kg/10 litres of material  – Calculate mass in kg/10 litres of the material from 
C.4.2 by multiplying the results by 10.  
C.4.4  Precision – With accurate control of temperature at ± 0.5 °C level, it is possible to achieve 
thefollowing precision.  
C.4.4.1  Repeatability  – The difference between two successive results obtained by the same operator within 
a short time interval, with the same appa ratus under constant operating conditions on identical test material 
shall not exceed 0.000 6 g/ml at the 95% confidence level.  
C.4.4.2  Reproducibility  – The difference between single and independent results obtained by different 
operators in different lab oratories on identical test material shall not exceed 0.001 2 g/ml at the 95% 
confidence level.  
C.4.4.3  In case of some liquid paint product s, especially those showing structure viscosity or thixotropy, the 
above precision limits may not be obtainable.  DRS 47 9: 2021  
11                ©RSB 2021 - All rights reserved  
 Annex  D 
(normative)  
 
Accelerated tests  
D.1 General  
These tests of chemical resistance, are included to assure the customer that the coating contains a sufficiency 
of cured resin to exhibit the long term requirements.  
D.2 Procedure  
D.2.1  Prepare the panels as per Annex H. Fo r the immersion tests as in D.2.2 to D.2.4, prepare and paint 
both sides of the panels and protect the edges of the panels by sealing with a chlorinated rubber paint.  
D.2.2  Resistance to sulphuric acid  
Immerse 3/4th of the panel in 30 percent sulphuric aci d for 24 hours. Remove the panel, wash in running fresh 
water and allow it to dry for an hour. Record the observation.  
D.2.3  Resistance to caustic potash  
Immerse 3/4th of the panel in 20 percent solution of potassium hydroxide for 24 hours. Remove the panel, 
wash in running fresh water, allow it to dry for an hour. Record the observation.  
D.2.4  Resistance to oil  
Immerse 3/4th of the panel in a mineral lubricating oil for 24 hours. Remove the panel and wipe the excess oil 
with cotton, wash it with m ineral turpentine and allow to dry for 30 minutes. Record the observation.  
D.2.5  Resistance to solvents  
Test one panel each for resistance to xylene, ethanol and acetone respectively. Take a clean white sterilized 
cotton and soak it in the solvent and place it on the panel without squeezing the cotton. Immediately cover the 
soaked cotton with a suitable watch glass and the leave it for 6 hours. Remove the watch glass and the 
soaked cotton, wipe the area with a clean dry cotton. Record the observation immediately .  
©RSB 2021 - All rights reserved                  12 
 Annex  E 
(normative)  
 
Durability tests  
E.1 General  
Both sides of the panels must be prepared and painted as per ISO 28199 -1 for normal outdoor exposure test 
as well as accelerated weathering test.  
E.2 Normal outdoor exposure test  
E.2.1  Expose the test panels in the open in duplicate at an angle of 45° facing south. The duration of test 
shall be for a period of 12 months. The test shall be started from any month in a calendar year. Examine the 
condition of the exposed films at monthly int ervals for the first quarter and thereafter quarterly for the rest of 
the period for the following characteristics:  
a) Gloss  
b) Colour  
c) Checking; cracking and flaking  
d) Chalking  
e) Spotting  
f) Blistering  
E.2.2  Wash the right hand half of the surface of the two test pane ls with 5 percent caustic soda solution 
followed by 5 percent hydrochloric acid solution and subsequent thorough rinsing with water. Wipe the panel 
with a clean soft cloth. Examine the same half of the test panels at each examination. As an aid in the 
exam ination, amagnifying glass may be used, but the valuation shall be based on an assessment with the 
unaided eye. At the end of the stipulated period for durability test, examine the two halves of the test panels. 
The sample shall be considered satisfactory if the material surface underneath as well as condition of the film 
in both the halves, the one washed periodically as well as the one washed onlyfor the final examination is 
satisfactory.  The requirements of this test shall be taken to have been satisfied  if performance in respect of 
the requirements given in table 1.  
E.3 Accelerated weathering test  
Carry out the test for 1 000 hours in a xenon arc type weatherometer (with rotating day/night device) with a 
cycle of 3 min. rainfall and 17 min. dry period. The r equirements of this test shall be taken to have been 
satisfied if performance in respect of the requirements given in table 1.  DRS 47 9: 2021  
13                ©RSB 2021 - All rights reserved  
 Annex  F 
(normative)  
 
Keeping properties  tests  
F.1 Scope  
This method determines the change in certain properties that may take place when pac kaged paint of either 
the solvent thinned or latex type is stored at normal room conditions.  
F.2 Apparatus  
F.2.1  Spatula weighing 45 ± 1 g with square ended blade, 120 mm in length and approximately 20 mm in 
width. It is prepared by cutting the tip from an ord inary 127 mm flexible steel laboratory spatula of the specified 
length.  
F.2.2  Paint brush nylon, 25 mm.  
F.2.3  Test surface, a smooth -surfaced paper chart coated with a suitable varnish or lacquer so as to render 
the surface impervious and resistant to pain t liquids.  
F.3 Procedure  
F.3.1  Open the container and note skinning, corrosion and odour of putrefaction, rancidity or souring. The 
other odours may be ignored. Skinning shall be designated as in Table F1.  
Table F1 – Designation of changes in skinning  
Grading  Description  
5 None  
4 Very slight  
3 Slight  
2 Moderate  
1 Considerable  
0 Severe  
F.3.2  Hold the can without shaking or agitation and examine the sample without the removal of 
supernatant vehicle. Determine the extent and character of portions of the paint that may have separated 
during storage by the use of spatula. Hold the spatula perpendicular to and in the centre area of the paint at a 
height whereby  the bottom edge of the spatula is level with the top of the can. Drop the spatula from that 
positi on. Rate the conditions of sample in accordance with table F2.  
NOTE – This test shall be carried out with the sample stored in one litre or smaller container.  
Table F2 – Rating for Degree of settling  
Rating  Description of paints condition   
©RSB 2021 - All rights reserved                  14 
 5 Perfect suspen sion. No change from the original conditions of the 
paint.  
4 A definite feel of settling and a slight deposit brought up on a spatula. 
No significant re sistance to sidewise movement of the spatula.  
3 Definite cake of settled pigment. Spatula drops throug h cake to 
bottom of container under its own mass. Define resistance to 
sidewise motion of spatula. Coherent portions of cake may be 
removed on spatula.  
2 Spatula does not fall to the bottom of container under its own mass. 
Difficult to move spatula throug h cake sidewise and slight edgewise 
resistance. Paint can be remixed readily to a homogeneous state.  
1 When spatula has been forced through the settled layer, it is very 
difficult to move spatula sidewise. Definite edgewise resistance to 
movement of spatula. Paint can be remixed to a homogeneous state.  
0 Very firm cake that cannot be reincorporated with the liquid to form a 
smooth paint by stirring manually.  
F.3.3  After examination of the entire sample as described in F.3.2, if a portion of the pigm ent has 
separated out to form a firm cake at the bottom of the container, pour the supernatant portion of the liquid into 
a clean container and hold for subsequent use. Reincorporate the separate cake by hand stirring with the 
spatula, adding back the liqu id in small amounts until the pigment has been reincorporated to form a 
homogeneous paint suitable for the intended use or until it is determined that the pigment cake cannot be 
reincorporated by hand stirring. Rate the condition of the sample in accordanc e with table F2.  
F.3.4  Apply the stored paint to one test panel and fresh control paint to the other. After the brushed film 
has completely dried, examine it for grains 0.8 mm in diameter, even larger gelatinous lamps, and streaks 
caused by such grains or lumps and designate as in table F1.  
NOTE  The use of mechanical shaker shall be avoided so that the lumps may not disperse.  
F.3.5  Determine  the mass per 10 litres of liquid paints prescri bed in Annex C. calculate the loss of mass 
resulting from storage.  DRS 47 9: 2021  
15                ©RSB 2021 - All rights reserved  
 Bibliography  
[1] IS 101-3-4, Methods of sampling and test for paints, varnishes and related products — Part 3: Tests on 
paint film formation — Section 4: Finish  
[2] IS 101-1-7, Methods of sampling and test for paints, varnishes and related products — Part 1: Test on 
liquid paints (general and physical) — Section 7: Mass per 10 litres  
[3] IS 101-6-2, Methods of sampling and test for paints, varnishes and related products — Part 6: 
Durability test on paint films — Section 2: Keeping properties  
 
 DRS 479: 2021  
 
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