TBS/CDC 7(5810) P 3 (Revision of TZS 506: 1996)  
 
 
 
 
 
 
©TBS 2020 – All rights reserved                                                              Second Edition 2020  DRAFT TANZANIA STANDARD  
 
 
 
Light kaolin  – Specification  
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
TANZANIA BUREAU OF STANDARDS  
 TBS/CDC 7(5811) P3  
2 
  
 
Foreword  
 
This Draft Tanzania Standard is being developed by the Industrial and Laboratory Chemicals 
Technical Committee under supervision of the Chemical s Division Standards Committee and 
it is in accordance with the procedures of the Bureau.  
 
This second edition cancels and replaces the first edition (TZS 506: 1996 Light kaolin  – 
Specification ) with changes on the test method for heavy metal.  
 
In reporting the result of a test or analysis made in accordance with this Tanzania Standard, if 
the final value, observed or calculated is to be rounded off, it shall be done in accordance w ith 
TZS 4 Rounding off numerical values.   TBS/CDC 7 (5811) P 3 
 
 
©TBS 2019 – All rights reserved                                                                                                   
 
  
 
  DRAFT TANZANIA STANDARD                TBS/CDC 7 (5810) P 3 
 
 
 
Light kaolin – Specification  
 
 
1. Scope  
 
This Draft Tanzania Standard prescribes the requirements and the methods of sampling and test ing 
of light kaolin for use in chemical industries. It does not apply for light kaolin used in pharmaceutical 
industry.  
 
2. Normative references  
The following referenced documents are indispensable for the application of this document. The 
latest edition of the referenced document (including any amendments) applies;  
 
TZS 59  Water for analytical laboratory use – Specification and test method  
TZS 74  Sulphuricacid - Specification  
TZS 386  Sampling of pure technical an d analytical sodium hydroxide  
 
3. Terms and definitions  
 
<<<<<Not applicable>>>>>  
 
 
4. Requirements  
 
4.1 General requirements  
 
4.1.1 Grades  
There shall be four grades of the material as follows  
Grade 1 - suitable for textile and paper coating industries  
Grade 2 - suitable for rubber Industry  
Grade 3 - suitable as filler in the paper industry  
Grade 4 - suitable as carrier in insecticide indus try 
 
4.1.2 Description  
 
4.1.2.1  The material shall be the beneficiated natural mineral powder consisting essentially of  
hydrate aluminum silicate. It shall be dry and free from extraneous impurities and grit.  
 
4.1.2.2  The material for use in textile and paper industries, the colour  shall be white, and for that 
used in rubber and insecticides, the colour may be white or cream.  
4.1.2.3 The material shall not contain any bluing or whitening  substances.  
4.1.2.4  For material required for textile industry shall conform to the following requirements;  
a) It shall disintegrate readily and form a smooth cream upon agitation when a lump  
©TBS 2020 – All rights reserved  
 of it is placed in water;  
b) It shall be able to make  a good fluid mixture when adhesive  is added: and  
c) It shall not show any definite structure when viewed under the microscope and 
shall be free from feldspathic material.  
 
4.2 Specific requirements  
The material shall also comply with the requirements laid down in table 1, when tested in  
accordance with the methods prescribed in annex A.  
 
Table 1 –Specific requirements for light kaolin  
 
S/N Characteristic  Requirements  Method 
of test  Grade 1  Grade 2  Grade 3  Grade 4  
1.  Coarse particles or grit 
represented as residue on 
53-micron sieve percent by  
mass, max 0.1 1.0 1.0 2.0 A.2 
2.  Particles larger than 10  
microns in diameter, 
percent  
by mass, max 5.0 7.0 20.0 20.0 A.3 
3.  Particles smaller than 2  
microns in diameter. per  
cent by mass, mi n. 62 50 35 35 A.4 
4.  Relative density at 22/27 
°C  2.5 – 2.9 A.5 
5.  Loss on drying, percent by 
mass, max 6.0 1.0 5.0 6.0 A.6 
6.  Loss on ignition, percent by  
Mass, max 14.0 A.7 
7.  Matter soluble in water,  
percent by mass, max N/A 0.5 0.5 N/A A.8 
8.  Matter soluble in  
hydrochloric acid, percent  
by mass, max 2.5 A.9 
9.  Arsenic (as As 2O3), mg/kg, 
max  10 10 10 10 A.11 
10.  pH value (of aqueous  
extract)  N/A N/A 4.5 – 7.5 N/A A.12 
11.  Oil absorption, ml per  
100 g, min  N/A 50 N/A N/A A.13 
12.  Colour reflectance to blue  
light of wavelength 5 040 
A°, percent  80 - 85 As agreed  
between the  
purchaser  
and the  
supplier  85 min  N/A A.14 
Note:  
N/A = “Not applicable; stands for parameters not applicable  for particular grade   
 
 
5 Packing and labelling  
 
5.1 Packing  
The material shall be supplied in sound, clean and dry containers and another  requirement as 
agreed between the purchaser and the supplier . 
 
 
 
 
  
 
©TBS 2019 – All rights reserved                                                                                             3 5.2 Labelling  
Each container shall legibly and indelibly label  with the information  below  either in English or 
Kiswahili or in combination as agreed between the manufacturer and/or the supplier. Any other 
additional language is optional.  
 
a) Name and grade /use of the material  
b) Name of the manufacturer and recognized trademark, if any  
c) Net content  
d) Date of manufacture  
e) Batch /Lot identification  
f) Instructions for handling  
 
6 Sampling  
 
The method of drawing representative samples of the material from a lot, the number of tests  
to be performed and the manner of determining the criteria for conformity of the requirements  
of this specification shall be as prescribed in annex B.  
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
  
©TBS 2020 – All rights reserved  
 Annex A  
(Normative ) 
 
Methods of test for light kaolin  
 
A.1 Quality of reagents  
Unless specified otherwise, pure chemicals and distilled water (see TZS 59)  
shall be employed in tests).  
 
A.2 Coarse particles or grit represented as residue on a 53 -micron sieve  
 
A.2.1  Reagents  
Tetrasodium pyrophosphate solution - 1%(m/v) 
 
A.2.2  Procedure  
Weigh about 200 g of the material and add it to about 1 litre of water in a glass or plastic  
vessel which is capable of being closed with a cap or bung. The vessel shall be of such a  
capacity that it is not more than about two -thirds full. Add 50 ml of tetrasodium pyrophosphate  
solution (this makes the wetting and subsequent dispersal and sieving easier). Close it, shake  
briefly and allow to stand for about 30 min to allow the material to wet thoroughly   
Mount the 53 -micron sieve over a sink and pour the slurry carefully from the vessel into the  
sieve. The passage through the sieve is assisted by impingement of a stream of water  
directed by hand from a flexible tube attached to the water supply the stream also serves to  
wash out the last traces of solids from the vessel into the sieve. Wash the residue on the  
sieve until the washings are clear and contain no solid particles. and then transfer by washing  
Into a porcelain dish. Evaporate the water and transfer the dry residue to a watch glass by  
brushing with a fine bristles brush  
 
A.2.3  Calculation  
 
 Coarse par ticles, percent by mass  = 100 ×𝑀1
𝑀2 
 
where  
𝑀1= mass in g of the residue obtained. and  
𝑀2= mass in 9 of the material taken for the test.  
 
A.3 Particles larger than 10 microns in diameter  
 
A.3.1  Outline of the method  
The method prescribed is the beaker sedimentation method and is useful for measurements  
in the range 4 to 40 microns It is based on Stokes law which defines the constant velocity  
reached by a sphere falling without turbulence, through a viscous fluid:  
 
V= 𝐺𝐷2(∆𝑑)
18𝜂 
 
where  
V= sedimentation velocity in cm/s  
G= acceleration due to gravity in  cm/sec2 
D = diameter of sphere in cm  
∆𝑑= difference in density between the sphere and the fluid.  
𝜂= viscosity of the fluid in poises (for china clay and water is 1.65 g/m):  
 
Note :𝜂 is temperature dependent so that if temperature is kept constant 𝜂,∆𝑑 and G are constants 
and V is proportional to the square of the diameter of the particles.  
Using this relationship,  it is possible to predict the depth of particles , starting in the free surface of 
the suspension,  after a certain time has elapsed. Clay particles are not spherical and particles sizes 
are expressed as equivalent spherical diameters or stoke diameters   
 
©TBS 2019 – All rights reserved                                                                                             5 For this test it is Important that two conditions are met  
a)The clay shall be completely dispersed and deflocculated, and  
b) The concentration of the solids in the suspension should not exceed 5 percent by mass.  
 
A.3.2  Reagents  
 
Deflocculat ing solution - prepared by mixing 10 g of anhydrous sodium carbonate and 5 g of 
sodium hexametaphosphate in 1 litre of water.  
 
A.3.3  Procedure  
 
Take a glass cylinder having approximate dimensions  of 5 cm internal  diameter and height of 30 
cm, and paint or inscribe a meniscus mark at a height of 20 cm above the internal  base. Place into 
this cylinder 20 ml of the deflocculat ing solution and 20.0 g of dry sample . Add water to the mark. 
Set aside the cylinder for about one hour after which close it with a rubber bung and  shake 
vigorously in order to disperse the clay ; Place th e cylinder on the bench and note the time. After 40 
minutes, decant the liquid carefully from the residue (a better alternative is to remove the liquid with 
a baffled Siphon tube connected to a water  jet vacuum pump; t his technique leaves the residue and 
about 1 cm of liquor  above it undisturbed). Fill the cylinder again to the mark with water and 5 ml of 
the deflocculating  solution, shake to suspend the particles, and after a further 40 minutes , remove 
the liquid again. Repeat this process twice to make a total of four sedimentations and decantation .  
Wash out the final residue with water into a porcelain dish and dry. Tran sfer the dry residue with a 
brush to a watch glass and weigh. This mass in g multiplied by 5 gives the percent age by mass of 
particles coarser than 10 microns.  
NOTE - Strictly these conditions apply to a temperature 290K  (16.85 °C)  but for coarse 
particle s, temperature fluctuations give rise to comparatively small errors an d thermostatic 
water baths are not essential . Corrections for ambient temperature are given below  
 
Temperature (273 °K) Time at 20 cm depth (minutes)  
  14    43.75     
  16    41.5 
  19   38.5 
  20    37.5 
  22   35.75  
A.4 Particles smaller than 2 microns in diameter  
A.4.1 Outlines of the method  
The method prescribed is the pipette Andersen method, and is useful for measurements in the 
range 0.5 to 4 microns. It is based on Stokes law and the principle is the same as described for the 
beaker method in A.3 1  
A.4.2  Apparatus  
The apparatus consists  of a thermostatic water bath , glass cylinders, tarred glass sample dishes 
and a special pipette. The latter is of 20 ml capacity and is mounted in a holder adjustable in height 
and in two directions in a horizontal place. Thus,  a number of cylinders may b e sampled in turn 
without disturbing their contents. The pipette holder also cranes  a probe which when brought into 
the meniscus of suspensions would dictate the depth of the   
©TBS 2020 – All rights reserved  
 pipette tip below the meniscus. Large vertical movements of the pipette are achi eved by  
means of a sliding clamp and fine movements by means of a rack and pinion gear . The  
pipette has two vacuum services from a single pump which enable samples to be taken either  
rapidly or slowly. For slow sampling , the filling time shall not be le ss than 15 seconds  
A.4.3  Reagent  
Deflocculant  solution - prepared by mixing 10 g of anhydrous sodium carbonate and 5 g of  
sodium hexametaphosphate in 1 litre of water.  
A.4.4 Procedure  
Take about 5 g of material which need not be dried or weighed accurately , and add to 5 ml of  
the deflocculant  solution in a cylinder of diameter 5 cm to 6 cm. Add water to a total volume  
of about 250 ml and place the cylinder in a water bath whose liquid depth is such  that no part  
of the suspension column is exposed.  
A.4.4.1  Allow a period of one hour to elapse to equalize temperatures  and to allow the clay to  
wet thoroughly . Remove the cylinder, close with a bung and shake vigorously to disperse the  
soaked clay lu mps. Replace the cylinder in the bath and immediately sample with the pipette  
regardless of the pipette depth . Discharge the 20 ml sample into a tarred glass dish which is  
placed on a water bath or suitable hot plate and evaporate its contents to dryness  without  
boiling. The mass of the clay from the sample is found to the nearest milligram (A).  
A.4.4.2  If the temperature of the bath is 297 ° K(23.85 °C) . Withdraw  a further sample slowly 3 hours 
39 minutes after the first sample and for this , the pipette  is lowered carefully into the liquid to  
avoid disturbing it. By means of tube globe  index, take the sample from a depth of 5 .0 cm  
below the free surface. The mass of solids in this second sample is determined as before (B).  
A.4.5  Calculation  
Mass B  expressed as a percentage of A  gives the percentage by mass of particles finer than 2 
microns. A small correction shall be applied because the soluble salts of the deflocculant solution 
are counted erroneously as clay. An empirical correction C shall be ap plied b y running a blank 
determination on a cylinder made up as usual but containing no clay. The mass of dissolved solids 
so obtained can be subtracted from A and B.  
Particles smaller than 2 microns , percent by mass = 𝐵−𝐶
𝐴−𝐶 ×100 
NOTE - The temperatu re of 297°K (23.85 °C) has been chosen in the above because the control of 
temperature is facilitated If the bath temperature is higher than all likely laboratory ambient 
temperatures. The times which should elapse between the two samplings at various temperatures for 
5 cm depth are given below  
 
Temperature (°K)  Time  
Hours  Minutes  
283 5 14 
285 4 56 
287 4 40 
289 4 26 
291 4 13 
293 4 10 
295 3 49 
297 3 39  
 
©TBS 2019 – All rights reserved                                                                                             7 299 3 30 
 
 
A.5 Relative density  
A.5.1  Apparatus  
A.5.1.1  Relative density bottle - 50 ml capacity, having a ground -in capillary stopper  
A.5.1.2  Vacuum  pump - with vacuum desiccators, capable of giving  a vacuum of 10 mm  
A.5.2  Procedure  
Weigh the empty, dry relative density bottle. Introduce  about 10 g of the material as dried in A.6 and 
weigh again. Nearly fill the relative density bottle with water and do not Insert the stopper ; Place it 
on a small tarred evaporating dish and keep the assembly in the exhausted recover of the vacuum 
pump ove rnight (at least 16 h) . Fill up the relative density bottle carefully with water and insert the 
stopper. It is possible that a very small portion of t he sample will run out of the sides of the stopper 
on inserting it. Wash down the particles thus forced ou t into the tarred dish . Wipe off the excess of 
water from the relative density bottle , bring it to 30 0 °K (26.85 °C) and weigh.  
A.5.2.1  Evaporate the contents of the tarred dish on a boiling water bath under cover, dry to 
constant mass at 378°K (104.85 °C) to 383°K  (109.85 °C)  
A.5.2.2  Empty the bottle, fill It With water and weigh after bringing it to 300 °K (26.85 °C)  
A.5.3  Calculation  
 
 
Relative Density at 300 /300°K = 𝑀2−𝑀1−𝑀4
(𝑀5−𝑀1)−(𝑀3−𝑀2)−𝑀4 
 
 
Where,  
𝑀1=mass in g of the empty relative density bottle ; 
𝑀2=mass in g of relative density bottle and sample ; 
𝑀3=mass in g of relative density bottle with sample and water ; 
𝑀4=mass in g of residue in tarred dish ; and  
𝑀5=mass in g of relative density bottle and water . 
 
 
A.6 Loss on drying  
A.6.1  Procedure  
Weigh about 20 g of the material and heat in a squat weighing bottle at 378 °K to  
383°K. Cool and weigh till constant mass is obtained. Preserve the sample in desiccators for  
subsequent tests . 
A.6.2 Calculation  
 
Loss on drying , percent by mass = 100  𝑀
𝑀1  
©TBS 2020 – All rights reserved  
 Where,  
𝑀= loss in mass in g, and  
𝑀1= mass in g of the mate rial taken for the test  
A.7 Loss on ignition  
A.7.1  Procedure  
Weigh about 1 g of the material in a porcelain or silica crucible ignite at about  1273 °K (999.85 °C) 
Cool and weigh till constant mass is obtained  
A.7.2  Calculation  
 
Loss on Ignition, percent by mass = 100  𝑀
𝑀1 
Where,  
𝑀= loss in mass in g, and  
𝑀1= mass in g of the material taken for the test  
 
A.8 Matter soluble in water  
A.8.1 Reagents  
A.8.1.1  Rectifie d spirit  – 95% ethanol  
A.8.1 .2 Bromophenol blue in dicator solution - Dissolve 0.1 g of bromophenol blue in 100 ml  
of rectified spirit  
A.8.1.3 Dilute hydrochloric acid - 0.1 mole/litre.  
A.8.2  Procedure  
Weigh about 10  g of the material in a 250 ml beaker. Add 5 ml of rectified spirit to  
wet the sample thoroughly. Add 200 ml of water  boil the suspension for 5 minutes and allow  
cooling  to room temperature . Add sufficient bromophenol blue indicator to give a visible  
colour, and then add dilute hydrochloric acid until the blue colour disappears.  
NOTE - Bromophenol blue turns yellow at about pH 4 at which point flocculation occurs 
and clears  filtration is obtain ed.  
Transfer the contents of the beaker to a 250 ml volumetric flask, dilute to the mark with water and 
mix well by shaking. Filter through a filter paper, rejecting the first 50 ml of filtrate. Place 100 ml of 
the clear filtrate into a tarred porcelain dish and evaporate to dryness on a water bath . Dry the 
residue at 378°K ±2°K, cool and weigh till constant mass is obtained.  
 
 
A.8.3  Calculation  
Matter soluble in water , percent by mass =250 ×𝑀1
𝑀  
 
©TBS 2019 – All rights reserved                                                                                             9 where  
𝑀1= mass in g of the residue obtained, and  
𝑀= mass in g of the material taken for the test  
 
A.9 Matter soluble in hydrochloric acid  
A.9.1 Reagent  
Dilute hydrochloric acid - 0.2 mole/litre  
A.9.2 Procedure  
Weigh about 2 g of the material. Transfer to a round -bottom flask with 100 ml of hydrochloric acid. 
Fix up a reflux condenser and boil the material on a sand bath for 5 minutes. Cool and filter through 
a sintered glass crucible No. G4. Wash free from chlor ides and evaporate the filtrate to dryness on 
a water -bath in a silica basin . After gentle heating, cool and weigh to constant mass.  
A.9.3 Calculation  
Matter soluble in hydrochloric acid , percent by mass =100  𝑀
𝑀1 
 
 
where  
M = mass in g of residue. and  
𝑀1= mass in g of the material taken for the test  
 
A.10 Copper  
 
A.10.1 Outline of the method  
 
Copper is determined  calorimetrically using sodium diethyldithiocarbamate by visual comparison.  
 
A.10.2  Apparatus  
Nessler cylinders - 100 ml capacity  
A.10.3  Reagents  
A.10.3.1 Concentrated ammonium hydroxide - 18 moles/litre (relative density 0.90)  
A.10.3.2  Ammonium Citrate solution - Dissolve 100 g of citric acid in 100 ml of ammonium  
hydroxide and make up to 200 ml with water.  
A.10.3.3  Gum Arabic solution - 5 percent (m/v).  
A.10.3.4 Sodium diethyldithiocarbamate solution  
Dissolve 10 g of sodium diethyldithiocarbamate  in 1000 ml of copper -free water ; keep in an amber -
coloured bottle and protect from strong light.  
A.10.3.5  Standar d copper solution - Dissolve 0.3928 g of copper sulphate crystals  
(CuS O4.5H2O) in copper -free water and make up the volume of 1000 ml with copper -free  
water. Take 100 ml of this solution and further dilute to 1 000  ml with copper -free water. One   
©TBS 2020 – All rights reserved  
 milliliter  of this solution is equivalent to 0.01 mg of copper oxide (as CuO)  
A.10.4  Procedure  
A.10.4.1  Prepare sample solution - Weigh accurately 2.0 g of the dry sample and mix with 8  
g of anhydrous sodium carbonate and fuse in a platinum crucible until the melt is clear. Leach  
out the melted mass with water into a porcelain dish and then put the crucible in the same  
dish. Add about 20 ml of water and heat on a water -bath until the pr oduct is disintegrated . 
Remove the crucible after washing in the dish. Evaporate the contents of the dish to dryness  
Add a mixture of 12 ml of concentrated sulphuric acid (see TZS 74, see clause 2) and 2 ml of  
concentrated nitric acid. Evaporate till fum es of sulphur trioxide appear. Dilute  to exactly 500  
ml and filter through a filter paper to remove silica. Use this prepared sample solution for the  
test under A. 13.  
NOTE - In case the prepared sample solution is turbid, add few drops of fer ric chloride 
solution (5 % (m/v), bo il and precipitate  twice with ammonium hydroxide solution, and filter.  
A.10.4.2  Pipette 25 ml of the prepared sample solution into a small conical flask or beaker ; 
Drop into it a small piece of litmus paper and make the solution just alkaline with ammonium  
hydroxide. Add 2.5 ml of ammonium hydroxide in excess and heat to boiling . Allow to stand  
on a water -bath for one hour to ensure complete precipitation of alumin um hydroxide and  
then filter through  filter paper (Whatman No.1 or equivalent) into a Nessler cylinder. Wash the filter 
paper with two or three small portions of hot water ; to the solution in the Nessler cylinder , add 5 ml 
of ammonium citrate, 5 ml of gum  Arabic solution , 10 ml of ammonium hydroxide solution and 10 ml 
of sodium diethyldithiocarbamate solution in the order  
mentioned. Dilute to 100 ml mark and mix thoroughly. To the other Nessler cylinder containing an 
equal aliquot of blank solution carrie d through the entire analysis in the same manner as the 
prepared sample solution, add equal amounts of the same reagents, dilute to about 90 ml and  
mix.  
Add to this solution standard copper solution from a 10 -ml burette until its colour matches that of 
the material under test after diluting to the same volume . Mix thoroughly  after each addition of 
standard copper solution  
If the colour  produced with the prepared sample solution is too deep for comparison, a  
smaller aliquot of the prepared sample solution from the acid digestion should be used . 
A.1 0.5  Calculation  
 
Copper (as CuO) percent by mass = 0.02 𝑉
𝑀 
 
 
 
where  
V= Volume in ml of standard copper solution used for the blank; and  
M = mass in g of the dry material taken for the test.  
 
A.11 Arsenic   
A.11.1 Sample preparation by microwave digestion  method   
 
©TBS 2019 – All rights reserved                                                                                             11  
A.11. 1.2 Reagents  
A.11.1.2.1  Conc. Hydrochloric acid (HCl)  
A.11.1.2.2  Conc. Nitric acid (HNO ₃) 
A.11.1.2.3  Conc. Hydrofluoric acid (HF)   
 
A.11. 2.3 Procedure  
Weigh 0.5 g of the sample into the digestion vessel. Add 3 mL of HCl, 1 mL of HNO ₃, and 7 mL of 
HF. S wirl the mixture gently and wait approximately 15 minutes before closing the vessel.  
. Allow any initial reaction to subside before sealing vessel.  
Note:  1- This procedure uses H ydrofluoric acid;  If it is necessary to complex the residual ,  
 Hydrofluoric  acid or re -dissolve insoluble fluorides formed, an additional    
 complexation step with boric acid should be used.  
 2- HF should be added slowly and carefully to the sample  
 3- The control test should be treated the same as the sample.  
 
A.11.2  Determination   
Determ ine the heavy metal (i.e. Arsenic) content using AAS or ICP methods.  
 
A.12 pH value  
 
Procedure  
Weigh about 25 g of the material and transfer it to a 500 ml beaker. Add 100ml of freshly  
boiled and cooled water. Allow to stand for 30 minutes with occasional stirring. Filter , reject  
the first 50 ml of the filtrate and collect the remaining filtrate i n a beaker. Determine the pH of  
the solution by means of a suitable pH meter using  glass electrodes.  
 
A.13 Oil absorption  
 
A.13.1 Procedure  
Place about 2 g of dry material, accurately weighed on a glazed porcelain, ground glass or  
marble plate. Add lin seed oil from a weighed dropping bottle, drop by drop and regularly each  
drop being mixed thoroughly  with the material using a palette knife. Mix the oil thoroughly in the 
course of 20 minutes into the whole of the material with the palette knife, until a  coherent  
mass is obtained . Weigh the dropping bottle again and determine by difference the weight of  
oil in grams. Where an approved sample is used for comparison , the oil absorption of the  
approved sample shall be determined by the same person and at the same time.  
 
A.13.2  Calculation  
 
Oil absorption, ml per 100 g = 108  𝑀
𝑀1 
 
where  
𝑀 = mass in g of the linseed  oil absorbed ; and  
𝑀1=mass in g of the dry material taken for the test . 
 
A.14 Colour  (reflectance to blue light of wavelength 0.504 µm) 5040 A  
A.14.1 Outline of the method   
©TBS 2020 – All rights reserved  
 The colour of the sample is compared with that of Lovibond magnesium Oxide block.  
A.14.2 Procedure  
By means of a suitable arrangement, light falling on a Lovibond magnesium oxide block shall be 
reflected on a selenium cell connected to a galvanometer. The galvanometric deflection is 
proportional to light reflected. For comparison, the reading obtained b y magnesium oxide block is 
taken as 100.  
Substitute the magnesium oxide block with a block prepared from a sample of the material. 
Measure the reflectance and report as colour (or reflectance) compared to that of magnesium oxide 
as 100. 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Annex B  
(Normative)   
 
©TBS 2019 – All rights reserved                                                                                             13 Sampling of light kaolin  
B.1 General Requirements  of sampling  
In drawing, preparing, storing and handling test samples, the following precautions and  
directions shall be observed  
B.1.1  Samples shall not be taken in an exposed place.  
B.1.2  Sampling instrument shall be clean and dry when used.  
B.1.3  Precautions sha ll be taken to protect the samples , the material being sampled , the  
sampling instrument and the containers for samples from contamination.  
B.1.4  The sample shall be placed in clean, dry, air -tight glass or other  suitable containers.  
B.1.5  The sample containers shall be of such a size that they are almost completely filled by  
the sample.  
B.1.6  Each sample container shall be sealed air -tight with  a stopper after filling and marked  
with full details of sample ; the date of sampling and other identification particulars.  
B.1.7  The samples shall be stored in such a manner that during storage the properties of the  
material do not get  affected .  
B.1.8  The sampling shall be done by a person or persons mutually agreed to between the  
purchaser and the supplier.  
B.2 Scale of sampling for material packed in bags  
B.2.1  Lot - In a single consignment all the material belonging to the same grade and comi ng  
from the same supplier or source shall constitute a lot.  
B.2.2  Sub-lot - For the purpose of sampling, all the material in a lot shall be divided into a  
suitable number of homogeneous sub -lots of approximately equal weight in accordance with  
columns 1 and 2 of Table 2 . 
 
B.2.3  The number of bags to be sampled from each sub -lot is given in c olumn  3 of table 3. These 
bags shall be selected at random from the sub -lot. In order to ensure the randomness of  
selection, random number tables shall be used. For guidance and use of random number  tables, 
TZS 386 may be referred. In the absence of random numb er tables,  
the following procedure may be adopted:  
 
Starting from any bag in the lot, count them as 1. 2. 3, etc, up to r and so on.  
Every rth container thus counted shall be withdrawn, r being the integral part of N/n.  
where N is the total number of containers in the lot, and n the number of containers to  
be chosen.  
 
 
 
 
 
 
 
 
Table 2 - Scale of sampling for bags - (clauses B.2.2 and B.2.3)   
©TBS 2020 – All rights reserved  
  
Number of bags in the lot  Number of sub -lots Number of bags to be 
sampled from each 
sub-lot 
Up to 10  1 5 
11 to 200  2 10 
201 to 500  3 15 
501 to 2 000  4 20 
2 001 and above  5 - 
 
B.3 Sampling from wagons  
B.3.1  Lot - In a single consignment all the material belonging to the same grade and coming from 
the same supplier or source shall constitute a lot.  
B.3.2  Sub-lot - For the purpose of sampling all the wagons in a lot shall be divided into a suitable 
number of homogeneous sub -lots of approximately equal weight in accordance with Table 3.  
 
Table 3 - Scale of sampling for wagons  
 
Weight of the material 
tonnes  Number of sub -lots Number of increments 
from each sub -lot 
Up to 200 2 20 
201 to 500  3 30 
501 to 2 000 4 40 
2 001 and above  5 50 
 
B.3.3  A minimum of 25 percent of wagons shall be selected at random from the sub -lot. The  
corresponding number of increments to be taken from a sub -lot shall be distributed over the  
selected wagons with a view to determin ing the number of increments that should be taken  
from each of the selected wagons in the sub -lot  
 
B.3.4  All the increments taken from the selected wagons in a sub -lot shall be pooled together  
to constitute a gross sample.  
 
B.4 Preparation of samples  
B.4.1 All the Increments from the same sub -lot shall be thoroughly mixed to constitute a gross  
sample representing the sub -lot the minimum size of the composite sample/gross sample shall be 
about 3 kg. If the gross sample is less than this, additional numb er of  
increments/portions shall be drawn so as to make up the required quantity.  
 
8.4.2  The composite sample/gross sample shall be suitably reduced by the method of coning  
and quartering or any other suitable method to about 750 g which shall be divided into three  
portions called laboratory sample, one for the purchaser , another for the supplier and the third as 
the refere nce sample , each duly placed in the sample container.  
 
8.5 Number of tests and criteria for conformity  
8.5.1  One laboratory sample from each sub -lot shall be tested individually for all the  
requirements of this specification and the sub -lot shall be considered satisfactory If the  
laboratory sample satisfies all the requirements of this specification  
8.5.2  The lot shall be declared to conform to the requirements of the specification if all the  
sub-lots (see B.5.1) are found satisfactory.