DEAS 25:2021  
ICS 97.180  
 
© EAC 2021                                                                                                                              Second Edition  
 DRAFT EAST AFRICAN STANDARD  
School chalk  — Specification  
EAST AFRICAN COMMUNITY  
 DEAS 25:2021 
ii © EAC 2021  – All rights reserved  
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Violators may be prosecuted . DEAS 25:2021 
© EAC 2021  – All rights r eserved  iii 
 Contents  Page 
Foreword  ................................ ................................ ................................ ................................ ............................  iv 
1 Scope  ................................ ................................ ................................ ................................ ......................  1 
2 Normative references  ................................ ................................ ................................ ............................  1 
3 Terms and definitions  ................................ ................................ ................................ ...........................  1 
4 Types  ................................ ................................ ................................ ................................ ......................  1 
5 Requirements  ................................ ................................ ................................ ................................ .........  2 
4.1 General requirements  ................................ ................................ ................................ ...........................  2 
4.2 Specific requirements  ................................ ................................ ................................ ...........................  2 
5 Packaging  ................................ ................................ ................................ ................................ ...............  3 
6 Labelling  ................................ ................................ ................................ ................................ .................  3 
8 Sampling  ................................ ................................ ................................ ................................ ................  3 
Annex  A (normative)  Measurement of length, diameter and weight  ................................ ............................  4 
A.1 Procedure  ................................ ................................ ................................ ................................ ...............  4 
A.2 Determination of weight ................................ ................................ ................................ ........................  4 
Annex  B (normative)  Determination of transverse b reaking strength  ................................ .........................  5 
B.1 Apparatus  ................................ ................................ ................................ ................................ ...............  5 
B.2 Procedure  ................................ ................................ ................................ ................................ ...............  6 
Annex  C (normative)   Determination of resistance to abrasion  ................................ ................................ .... 7 
C.1 Apparatus  ................................ ................................ ................................ ................................ ...............  7 
C.2 Procedure  ................................ ................................ ................................ ................................ ...............  8 
Annex  D (normative)  Determination of free moisture content ................................ ................................ .... 10 
D.1 Procedure  ................................ ................................ ................................ ................................ .............  10 
D.2 Calculation  ................................ ................................ ................................ ................................ ...........  10 
Annex  E (normative)  Determination of calcium sulphate content  ................................ .............................  11 
E.1 Reagents  ................................ ................................ ................................ ................................ ..............  11 
E.1.1  Quality o f reagents  ................................ ................................ ................................ ..............................  11 
E.1.2  Ammonium acetate solution  ................................ ................................ ................................ ..............  11 
E.1.3  Diatomaceous silica  ................................ ................................ ................................ ............................  11 
E.1.4  Ammonium hydroxide, ................................ ................................ ................................ ........................  11 
E.1.5  Ammonium wash solution  ................................ ................................ ................................ ..................  11 
E.2 Procedure  ................................ ................................ ................................ ................................ .............  11 
E.3 Calculation  ................................ ................................ ................................ ................................ ...........  11 
Annex  F (normative)  Determination of calcium carbonate content  ................................ ...........................  13 
F.1 General  ................................ ................................ ................................ ................................ .................  13 
F.2 Procedure  ................................ ................................ ................................ ................................ .............  13 
Annex  G (normative)  Sampling Criteria  ................................ ................................ ................................ ........  14 
G.1 General precautions  ................................ ................................ ................................ ............................  14 
G.2 Scale of sampling  ................................ ................................ ................................ ................................  14 
G.3 Number of test and criteria for conformity  ................................ ................................ .......................  14 
Bibliography  ................................ ................................ ................................ ................................ ......................  16 
 
 DEAS 25:2021 
iv © EAC 2021  – All rights reserved  
 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 envisag ed 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 Committee  (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 from the public and private sector 
organizations  in the community .  
East African Standards are developed through  Technical Committees that are representative of key 
stakeholders including government, academia, consumer groups, private sector and other interested parties. 
Draft East African Standards are circulated to stakeholders through the Nat ional Standards Bodies in the 
Partner States. The comments received are discussed and incorporated before finalization of standards, in 
accordance with the Principles and procedures for development of East African Standards. XXXXXX.  
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 always have the latest versions of the standards 
they are implementing .  
The committee responsible  for this docu ment is Technical Committee EASC /TC 079, Scholastic materials  
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 or all such patent rights.  
This second edition cancels and replaces the first edition (EAS 025:2000 ), which has been technically revised.  
 DRAFT EAST AFRICAN STANDARD  DEAS 25:2021 
 
© EAC 2021  – All rights reserved  1 
 School chalk — Specification  
1 Scope   
This Draft East African Standard specifies requirements, sampling and test methods for solid white and 
coloured school chalks intended to be used on chalkboards.  
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 document (including any amendments) applies.  
ISO 17318, Solid fertilisers and soil conditioners — Determination of arsenic, cadmium. Chromium, lead and 
mercury contents . 
3 Terms and definitions  
For the purposes of this document, the follow ing terms and definitions apply. ISO and IEC maintain 
terminological databases for use in standardization at the following addresses: — ISO Online browsing 
platform: available at http://ww w.iso.org/obp  
3.1 
lot 
not more than 1 000 000 chalks of the same type in containers bearing the same batch identification, from one 
manufacturer, submitted at any one time for inspection and testing .  
3.2 
batch 
material from a single mix or, in the case of  a continuous production process, the material from a single day's 
production  
4 Types  
The three types of school chalks shall be as follows:  
a) Soft chalks;  
b) Hard chalks; and  
c) Soft dust -free chalks   DEAS 25:2021  
2 © EAC 2021  – All rights reserved  
 5 Requirements  
5.1 General requirements  
5.1.1 The school chalk shall be made from good quality calcium sulphate (calcined gypsum, 
CaSO4.½H2O), calcium carbonate (limestone, CaCO3) or a mixture of both types of materials  
5.1.2 The school c halk shall not contain poisonous or toxic materials in quantities harmful or injurious to 
human life.  
5.1.3 The school chalk  shall be of homogeneous mass free from grease, grit and sandy particles liable to 
scratch the surface written upon  
5.1.4 Chalk sticks shall be  circular in cr oss-section, uniformly tapered or tapered at one e nd as per table 1.  
5.1.5 The finish shall be smooth and at least 75% of the school chalk sticks  shall be free from external 
blowholes, depressions and signs of crumbling.  
5.1.6 Chalk sticks shall, freely without scratching or otherwise harming the chalkboa rd, produce visible and 
distinct marks that can be easily erased by a dry eraser such as a piece of dry cloth.  
5.1.7 The white chalks shall be clear without showing any traces of other colours.  
5.1.8 The coloured chalks shall be of the declared colour, pre ferably chosen from the following standard 
colours: blue, brown, green, red and yellow.  
5.2 Specific requirements  
The school chalk  shall comply with the requirements given in Table 1 when tested in accordance with the 
methods prescribed therein.  
Table 1 – Specific requirements for school chalks  
S/N Parameters  Requirements  Test 
methods  Soft Hard  Soft dust  
free 
1 Dimensions, 
mm Length  81.0 ± 2.0 76.0 ± 2.0 78.0 ± 2.0 Annex A  
Diameter  At the base  11.0 ± 1.0  9.5 ± 1.0  9.5 ± 1.0  
At the tip  9.5 ± 1.0 9.5 ± 1.0 9.5 ± 1.0  
2 Average w eight per chalk stick, g , min  5 Annex A 
3 Transverse breaking strength, kg, min 1.200 1.800 1.200 Annex B 
4 Resistance to abrasion, cm3 0.13 ─ 0.26 0.10 ─ 0.16 0.08 ─ 0.16 Annex C 
5 Free m oisture content, % by mass, max  12 12 12 Annex D 
6 
 Freedom from 
poisonous and toxic 
materials, mg/Kg, max  Lead, Pb 10 ISO 
17318 Arsenic as As2O3 2 
Cadm ium 7 
Chromium  10 
Mercury  2 
7 Quality of raw 
materials1, % by Calcium Sulphate / 
Calcined Gypsum  (as 
CaSO 4.1/2H2O) 90 Annex E                     DEAS 25:2021  
© EAC 2021  – All rights r eserved  3 
 mass, min.a Calcium carbonate 
(as CaCO 3) 90 Annex F 
a In case both calcium carbonate and calcium sulphate are used, the total content of the raw material should not be less than 90% and 
the portion should be defined by the manufacturer.   
6 Packaging  
The product shall be packaged in suitable containers, which offer adequate protection of the content during 
transportation , handling and storage .  
7 Labelling  
Each packa ge shall be legibly and indelibly labelled in English and/or any other official language (French,  
Kiswahili, etc.) used in the importing East African Partner State with the following information:  
a) Name of product as  “School chalk”  
b) Colour  
c) Name of the materia l of the chalk;  
d) Type of chalk ;  
e) Number of chalk sticks  in the box;  
f) Manufacturer’s name and address  
g) Registered Trademark if any  
h) Manufacturing  date 
i) The batch number  
8 Sampling  
Sampling shall be done in accordance with Annex G.  DEAS 25:2021  
4 © EAC 2021  – All rights reserved  
 Annex  A 
(normative)  
 
Measurem ent of length, diameter and weight  
A.1 Procedure  
Measure the length and diameter at two ends of only full -length chalk by means of callipers and a foot -rule 
calibrated in millimetres or with sliding calliper gauge.  
A.2 Determination of weight  
Weigh 10 % of the chalk  sticks, drawn from the same box at a t ime and compute the average mass per chalk  
stick. The average mass computed per chalk stick shall be obtained from triplicate, and shall not differ by 
more than two percent.                      DEAS 25:2021  
© EAC 2021  – All rights r eserved  5 
 Annex  B 
(normative)  
 
Determina tion of transverse breaking strength  
B.1 Apparatus  
Metal apparatus, of such construction that a chalk can be supported on two parallel edges while a load is 
applied through an anvil positioned midway between and parallel to the two supports (figure B1), a nd capable 
of applying a steadily increasing load of 0 kg to 2 kg to the chalk under test, and of indicating the applied load  
 
 
Figure B 1 – Determination of transverse breaking strength  
 
DEAS 25:2021  
6 © EAC 2021  – All rights reserved  
 B.2 Procedure  
B.2.1  Test, in turn, each chalk reserved in terms of determination of transverse breaking strength.  
B.2.2  So secure the supporting edges that the distance between them is appropriate to the product being 
tested.  
B.2.3  Centre a chalk on the two supporting edges, and lower the load ing anvil until it touches the specimen 
under test  
B.2.4  Increase the load steadily at a rate of 50 g to 100 g per second and record the load at which the 
specimen breaks.  
B.2.5  Determine whether the lot complies with the requirements of this specificatio n                     DEAS 25:2021  
© EAC 2021  – All rights r eserved  7 
 Annex  C 
(normative)  
 
Determination of resistance to abrasion  
C.1 Apparatus  
C.1.1  Sliding platform A, of width 190 mm, of length 330 mm, fitted with clamps 250 mm apart and suitable 
for clamping down the standard abrasive paper (see C.1.5), and with a st roke of 230 mm.  
C.1.2  Bracket B, of length 180 mm, fitted to the base on which the platform slides, and with two holes in 
each upright so that the spindle of the balance arm C can be supported either 38 mm or 57 mm above the top 
of the sliding platform.  
C.1.3  Balance arm C, fitted with platform D and an adjustable counter -mass E, and that is capable of sliding 
on its spindle along the length of the bracket B.  
C.1.4  Holder F, secured to the centre of the lower surface of platform D, and in which a chalk c an be 
securely clamped, the clamp being so constructed that it will not damage the test specimen.  
C1.5  Abrasive paper, standard waterproof silicon carbide, of grade No. 400.  
C.1.6  Graduated measuring cylinder, of capacity 100 cm3. 
 
 
 
 
 DEAS 25:2021  
8 © EAC 2021  – All rights reserved  
 Key 
A Sliding pla tform  
B Bracket  
C Balance arm  
D. Platform  
E Adjustable counter -mass  
F Holder  
Figure C1 — Apparatus or determining resistance to abrasion  
C.2 Procedure  
C.2.1  Cut the appropriate specimens to a length of 57 mm of chalks. Abrade both ends of each specimen 
on a piece of abrasive paper until the ends are flat and square, then determine the mass of each specimen to 
the nearest milligram.  
C.2.2  Clamp the abrasive paper to the sliding platform. With the balance arm installed at the appropriate 
height given in tab le C1, secure the test specimen vertically in holder F (in case of tapered chalks, clamp the 
thick end), and set the balance arm in equipoise by adjusting the position of the counter -mass. So adjust the 
specimen that the entire tip is in contact with the a brasive paper. If this is not possible, repeat C.2.1.  
C.2.3  Move the balance arm to one extreme of its travel on its spindle, load the platform D with the 
appropriate mass given in table C1 and draw the sliding platform out to its limit at a uniform rate and in such a 
way that the stroke is completed in 4 s to 5 s. so move the balance arm on its spindle that the end of the chalk 
rests on a clean part of the abrasive paper and next to the line formed by the previous stroke. Push the sliding 
platform in at a  uniform rate and in such a way that the stroke is completed in 4 s to 5 s. Repeat this 
procedure until 10 strokes have been made  
Table C 1 – Resistance to abrasion  
Product  Height of balance arm 
(above sliding platform)  Mass to be placed on 
platform  
Chalks  (soft, hard 
and soft dust -free) 57 113 
 
C.2.4  Remove the test specimen from the holder, determine the loss in mass by again determining the 
mass to the nearest milligram and set it aside for the determination of apparent density.  
C.2.5  Repeat the test o n each specimen in the lot.  
C.2.6  Determine, to the nearest tenth of a gram, the combined mass of the abraded specimens and set 
them aside in terms of C.2.4 and C .2.5. Determine the volume of each specimen as follows:  
a) Soft and hard chalks: immerse four s pecimens in water for 1 h. Wipe off the excess water with a filter 
paper. Pour sufficient water into a 100 cm3 measuring cylinder to ensure that the specimens will be 
fully immersed. Record the volume of water, then immerse the specimens, ensuring that no air 
Bubbles are present and  determine the volume (in cubic centimetres) of water displaced by the 
specimens  
b) Dust-free chalks: using callipers, measure the length and diameter or cross -section of each specimen 
and calculate its volume, in cubic centimetres.                       DEAS 25:2021  
© EAC 2021  – All rights r eserved  9 
 C.2.7  In the case of chalks, calculate the apparent density of the specimens by dividing their total mass by 
their total volume. Using the figure for the mass of chalk abrade d from each test specimen (see C .2.4), 
calculate the average mass of chalk abrad ed from each specimen and divide this by the apparent density to 
obtain the average volume, in cubic centimetres, abraded from each specimen.  DEAS 25:2021  
10 © EAC 2021  – All rights reserved  
 Annex  D 
(normative)  
 
Determination of  free moisture conten t 
D.1 Procedure  
Grind in a mortar about four chalks so as to pass through 1.00 mm sieve. Weigh accurately about 10 g of the 
ground sample and spread it in a thin layer in a Petri dish. Place it in an oven maintained at 100 ± 2 ºC till 
constant mass is obtained.  
D.2 Calculation  
 
Where:  
 m = mass in g of the m aterial taken for the test, and  
 m1 = mass in g of the material after drying.                      DEAS 25:2021  
© EAC 2021  – All rights r eserved  11 
 Annex  E 
(normative)  
 
Determination of calcium sulphate content  
E.1 Reagents  
E.1.1  Quality of reagents  
Pure chemicals and distilled water shall be used in the test.  
NOTE  Pure chemicals shall mean chemicals that do not contain impurities, which affect the result of analysis.  
E.1.2  Ammonium acetate solution  
Dissolve 454 g of ammonium acetate in two litres of water. Add aqueous ammonia solution to make the 
solution distinctly  ammoniacal.  
E.1.3 Diatomaceous silica  
Wash kieselguhr free from soluble matter and dry to constant mass at 105 ºC to 110 ºC.  
E.1.4  Ammonium hydroxide,  
20 % by mass  
E.1.5  Ammonium wash solution  
Dilute 100 ml of aqueous ammonia solution to one litre with water.  
E.2 Procedure  
Grind the sample in a mortar so as to pass through a 250 micro sieve. Place about 4 g of the sample, 
accurately weighed, in a 600 ml beaker. Add 350 ml of ammonium acetate solution stirring the mixture 
thoroughly so as to loosen the matter from the bottom of the beaker. Add about 0.2 g of diatomaceous silica, 
accurately weighed, to the mixture and heat at 70 ºC on a steam bath for 30 minutes with frequent stirring. 
Keep the solvent distinctly ammoniacal during this period by adding aq ueous ammonia solution, if necessary. 
Filter the mixture through a weighed Gooch crucible applying suction, if necessary. Stir frequently to keep the 
diatomaceous earth suspended in the liquid. Wash the residue with five 10 ml portions of hot ammonium 
acetate solution, draining thoroughly on each washing. Repeat washing with eight 10 ml portions of ammonia 
wash solution. Dry the crucible in an oven at 70 ºC to constant mass.  
E.3 Calculation  
 
 
 DEAS 25:2021  
12 © EAC 2021  – All rights reserved  
 Where:  
m mass in g of the material taken for the test  
m1   final mass in g of the crucible and the contents after drying  
m2 = initial mass in g of the crucible plus mass in g of diatomaceous silica used as filter aid, and  
m3 = mass in g of moisture present in the sample                      DEAS 25:2021  
© EAC 2021  – All rights r eserved  13 
 Annex  F 
(normative)  
 
Determination of calci um carbonate content  
F.1 General  
F.1.1  The approach is known as a back titration. A measured mass of chalk from the cliff is weighed out and 
then dissolved completely in an excess of hydrochloric acid. The resultant solution is made up to the mark in a 
250 ml volumetric flask.  
F.1.2  A titration is then carried to determine the concentration of the excess hydrochloric acid in the flask. 
Knowing the excess and the original amount of acid, it can work back (hence back titration) to find the amount 
of acid re acting with the calcium carbonate in the chalk.  
F.2 Procedure  
F.2.1  Weigh out accurately 1.30 g of a sample of naturally occurring chalk;  
F.2.2  Dissolve this mass of chalk in 50 ml of 1M hydrochloric acid solution in a 250 ml beaker;  
F.2.3  Transfer the  contents of the beaker and all washings to a 250 ml volumetric flask and make up to the 
mark with distilled water;  
F.2.4  By pipette extracts 25 ml of the acid solution from the volumetric flask and transfers it to a 250 ml 
conical flask;  
F.2.5  Titrate t his aliquot of the acid solution with 0.1 M sodium hydroxide solution using phenolphthalein 
indicator: the end point occurs with the first faint pink tinge to the solution in the flask;  
F.2.6  Repeat the titration until you have concordant results, i.e. ti tres to within 0.1 ml of each other  DEAS 25:2021  
14 © EAC 2021  – All rights reserved  
 Annex  G 
(normative)  
 
Sampling Criteria  
G.1 General precautions  
G.1.1 Samples  shall be drawn from originally unopened and undamaged boxes.  
G.1.2 Samples shall be protected from abnormal exposure to heat, and shall not b e exposed to any liquid.  
G.1.3 Samples shall be handled as little as possible, and contact with wet or sweated hands shall be 
avoided  
G.2 Scale of sampling  
6.2.1 In any consignment, all boxes of school chalks drawn from a single batch of manufacture shall  
constitute a lot. If the consignment is declared or known to consist of different batches of manufacture, the 
boxes belonging to the same batch shall be grouped together and each such group shall constitute a separate 
lot.  
G.2.2 For ascertaining the conf ormity of the lot to the requirements of the specification, tests shall be carried 
out for each lot separately. The number of boxes to be selected from lots of different sizes shall be in 
accordance with table 2. From each selected box, 10 chalks shall be picked up at random.  
G.2.3 To ensure randomness of selection, the following procedure is recommended for use.  
G.2.4 Count the boxes in a systematic manner as 1,2,3… up to r and so on, where r is the integral part of 
N/n (N and n being the number of boxes  in the lot and number of boxes to be selected respectively). Every nth 
box thus counted shall be selected until the requisite number of boxes is obtained.  
G.2.5 From each of the boxes thus selected, 10 chalks shall be picked up blind from different place s. 
Table G1 – Scale of sampling and permissible number of defectives  
Number of boxes in 
the lot (N)  Number of 
boxes to be 
selected (n)  Total number of 
chalks to be 
selected(n)  Permissible 
number of 
defective chalks  
Up to 5  1 10 0 
6 to 50  3 30 1 
51 to 10 0 5 50 2 
101 to 500  10 100 4 
More than 500  15 150 6 
 
G.3 Number of test and criteria for conformity  
G.3.1 All the chalk selected according to clause G.2 shall be examined for the requirements in clause 3, If 
the number of defectives found are equal to or less than the corresponding number given in col. 4 of Table G 1 
the lot shall be declared as conforming to the specification requirements in Clauses 4.1.                     DEAS 25:2021  
© EAC 2021  – All rights r eserved  15 
 G.3.2 All the ch alks selected according to G .2. shall then be examined for length of the stick and d iameter at 
the two ends. Any chalk failing to meet the requirements of either length or diameter shall be considered as 
defective.  
G.3.3 If the number of defective chalks found is less than or equal to the corresponding num ber given in 
Column 4 of Table G 1, the lot shall satisfy the requirements of length and diameter as prescribed in Table 1 
G.3.4 Calcium sulphate content, Calcium Carbonate content and free moisture content shall be determined 
on a suitable number of chalks after crushing them to the requ ired fineness.  
G.3.5 Five chalks shall be select ed from those got according to G .2.2 and subjected to transverse breaking 
strength test separately.  
G.3.6 A lot shall be declared as conforming to the requirements of calcium sulphate, Calcium Carbonate 
mois ture content and transverse breaking strength if all the test results obtained are found satisfactory.  
G.3.7  A lot shall be declared satisfactory to the requirements of this specification if the st ipulations laid 
down in clause 5, 6 and 7  have been met  
 DEAS 25:2021  
16 © EAC 2021  – All rights reserved  
 Bibliography  
[1] DRS 409: 2019 , School chalk — Specification  
[2] EAS 25:2000, School chalk — Specification  
[3] TZS 68: 201 5, Writing chalks —Specification  
 DEAS 25:2021   
 
© EAC  2021  – All rights reserved