TBS/CDC 7 (6543) P 3 (Revision of TZS 1362: 2010 ) 
© TBS 2020   Second Edition  
  
 
 
DRAFT TA NZANIA STANDARD 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Cashew nut shell liquid (CNSL) — Specification  
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
TANZANIA BUREAU  OF STANDARDS  
 
 
 
 
  
 
 
 
 
 
 
 
 
  
© TBS 2020   Second Edition 2020  
 
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 Foreword 
This Tanzania Draft Standard was prepared by the Technical Committee on  Industrial and laboratory 
chemicals under supervision of Chemicals Divisional Standards Committee and it is in accordance with 
the procedures of the Tanzania  Bureau of Standards.  
This second  edition  cancels and replaces the first  edition, TZS 1362: 2010 Cashew nut shell liquid 
(CNSL) – Specification  with the following technical revision:  
i) Removing Rosenmund – Kuhnhenn Method  due to prohibition of using pyridine chemical ; and  
ii) Addition of requirement for Refractive index  parameter  
For the purpose of deciding whether a particular requirement of this standard is complied with, the final 
value observed or calculated expressing the result(s) of a test or analysis shall, be rounded o ff in 
accordance with TZS 4 Rounding off numerical values . The number of significant places retained in the 
rounded off value should be the same as that of the specified value in this standard.  
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
  
© TBS 2020   Second Edition 2020  
 
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 TBS/CDC 7 (6543) P 3 
 
 
Cashew nut shell liquid (CNSL) — Specification  
 
 
1. Scope  
This draft Tanzania Standard specifies the requirements, methods of sampling and tests for cashew  
nut shell liquid (CNSL ) for industrial use.  
Note: Cashew  nut shell liquid (CNSL ) is used as a phenolic component in many commercial resins, 
resinous compositions, moulding compositions, protective coatings , insulating varnishes  and others .  
 
2. Normative references  
The following normative references are indispensable for the applicatio n of this standard. For dated 
references, only the edition cited applies. For undated references, the latest edition of the normative 
references (including amendments) applies ;  
TZS 4 Rounding off numerical values  
 
3. Terms and definitions  
 
<<<<<<<<Not applicable>>>>>>>>  
 
 
4. Requirements  
 
4.1. General requirements  
4.1.1  Appearance – The material shall be free from separated water and extraneous matter s. 
4.1.2  Colour  – The material shall not be deeper than dark brown when viewed through transmitted 
light.  
4.2. Specific requirements  
The material shall also comply with the following  specific  requirements given in Table 1, when tested 
according to the methods prescribed in the Annex A.  
 
 
 
 
 
 
 
DRAFT TANZANIA STANDARD   
© TBS 2020   Second Edition 2020  
 
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 Table 1 – Specific requirements of Cashew  nut shell liquid (CNSL)  
SL 
No.            Characteristic  Requirement  Method of test  
i.  Specific gravity, 30 °C 0.950 – 0.970  A-2 
ii.  Viscosity at 30 °C, in centipoises, Max. 550 A-3 
iii.  Moisture, percent by mass, Max.  1.0 A-4 
iv.  Matter insoluble in toluene, percent by mass, Max.  1.0 A-5 
v.  Loss in weight upon heating, percent by mass, Max.  2.0 A-6 
vi.  Ash, percent by mass, Max.  1.0 A-7 
vii.  Iodine value, Min. 
a) Wij’s method  
b) RK method   
250 
290 A-8 
A-8.1 
A-8.2 
viii.   Polymerization  
a) Time in minutes, Max.  
b) Viscosity at 30  °C, in centipoises, Min. 
c) Viscosity after acid washing at 30  °C, in 
centipoises, Min.  
4 
30 
200  
A-9 
A-10 
A-11 
ix.  Refractive index  (25 °C)  1.693 – 1.698  A-12 
 
5. Packaging and Labelling  
5.1 Packaging  
The material  shall be packed in a suitable airtight container that prevents it from deterioration of its 
quality during storage, transportation and handling.  
5.2 Labelling  
Each container shall be securely closed, legibly and indelibly label with the information below  either in 
English or Kiswahili or in com bination as agreed between the manufacturer and/or the supplier. Any 
other additional language is optional.  
a) the name of the product as Cashew nut shell liquid (CNSL) ; 
b) name and address of the manufacturer;  
c) net content;  
d) date of manufacture;  
e) batch number;  
f) best before date; and  
g) instructions for storage, use, disposal and safety precautions.  
 
6. Sampling  
 
The method of drawing representative test samples of the material and the criteria for conformity shall 
be as prescribed in Annex B.  
  
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 Annex  A: 
 
(Normative)  
 
Analysis of the cashew nut shell liquid  (CNSL)  
 
 
A.1 Quality of reagents  
Unless specified otherwise, chemicals for analytical use and distilled water quality shall be used.  
 
A.2 Determination of specific gravity  
 
A.2.0 Principle  
The specific gravity of the material is determined with a specific gravity bottle.  
 
A.2.1  Preparation of the sample  
Filter the material through a filter paper, glass wool or any other suitable filtering medium to remove 
traces of suspended impurities. Suction may be used if necessary.  
 
A.2.2 Apparatus  
A.2.2.1  Thermometer  – Any convenient thermometer of a suitable range with 0.1 or 0.2 °C subdivisions.  
 
A.2.2.2  Water -Bath 
 
A.2.2.3  Specific Gravity bottle  – A specific gravity bottle of about 50 mL capacity with w ell fitted ground 
glass joints and of the shape as shown in Fig. 1 is recommended. To calibrate, clean and dry the bottle 
thoroughly, weigh and then fill with boiled and cooled water at 30 °C. Fill to overflowing by holding the 
bottle on its side in such a  manner as to prevent the entrapment of air bubbles. Insert the stopper and 
immerse in water bath at 30 °C ± 0.2 °C. Keep the entire bulb completely covered with water and hold 
at that temperature for 30 minutes. Carefully remove any water, which has exude d from the capillary 
opening. Remove from the bath, wipe to completely dry, cool to room temperature and weigh. Calculate 
the weight of water. This is a constant for the bottle but should be checked periodically.  
 
 
 
 
Fig. 1:  50 mL Specific gravity bottle  
A.2.3 Procedure  
Fill the specific gravity bottle with the material to over -flowing, holding the bottle on its side in such a 
manner as to prevent the entrapment of air bubbles. Insert the stopper and immerse in water bath at 
30 °C ± 0.2 °C and hold for 30 min . Carefully wipe off any oil, which has come through the capillary 
 
© TBS 2020   Second Edition 2020  
 
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 opening. Remove the bottle from the bath and completely dry it by wiping.  Cool to room temperature 
and weigh.  
 
A.2.4 Calculation  
Specific gravity at 30 °C = A – B 
                                               C – B 
Where  
             A is the mass in g of the specific gravity bottle with material at 30 °C, 
             B is the mass in g of the specific gravity bottle, and  
             C is the mass in g of the spe cific gravity bottle with water at 30 °C. 
 
A.3 Determination of viscosity  
 
A.3.0 Principle  
The viscosity of the material is determined with a U -tube viscometer.  
 
A.3.1 Apparatus  
 
A.3.1.1  U-Tube Viscometer – The U -tube viscometer as shown in Fig. 2 shall be homogenous 
transparent glass and shall be free from mechanical imperfections. All glass tubing used in the 
construction of the viscometer shall be of the same composition and the finish ed instrument shall be 
thoroughly annealed.  
 
A.3.1.2  Thermometer – Any convenient thermometer of a suitable range with subdivisions of 0.2  °C 
 
A.3.1.3  Water -bath – A water -bath, suitable for immersion of the viscometer to within 5 cm from the top, 
with pro vision of visibility of the instrument and the thermometer, shall be provided. The viscometer may 
be fixed as an integral part of the bath. The thermometer shall be mounted with the bulb near the centre 
of the viscometer. The bath shall be regulated so tha t the variation in the thermometer reading does not 
exceed 0.2 °C.  
A.3.1.4  Time Recording device – A suitable stop watch.  
 
A.3.1.5  Frame – Suitable frames shall be provided so that the viscometers may be suspended securely 
in the bath in a vertical positi on. 
 
A.3.2 Procedure  
 
A.3.2.1  Clean the viscometer by rinsing with suitable solvents, such as isopropyl alcohol followed by 
ethyl ether or petroleum hydrocarbon solvents. Remove each solvent by passing a current of dry air 
through it and take care that no moisture remains inside the instrument.  
 
A.3.2.2  Fill the viscometer by holding it in an inverted position with the capillary side submerged in the 
material under test. Apply suction to the arm of the viscometer either by sucking through a piece of 
rubber tubing or water aspirator. Fill the main reservoir A and bring the liquid into the capillary to the 
etched line just below A. Wipe the excess liquid off the end of the capillary arm and incline the instrument 
slightly to cause the oil to flow by gravity  from the upper capillary into A. Discharge this small amount 
of liquid into the main capillary leading to bulb B. Slip a short piece of rubber tubing with a pinch clamp 
over the open end of the upper capillary to close one end. Turn the viscometer to a ve rtical position and 
place in the constant temperature bath maintained at 30  °C ± 0.2 °C. During this time, prevent the 
entrance of dust and moisture. Remove the pinch clamp when the equilibrium is reached and allow the 
liquid to flow by gravity. Start the stopwatch just when the liquid passes the etched line between B and 
C. Note the time required for the meniscus to reach the etched line above C [efflux time (i)] and then to 
the etched line above D [efflux time (ii)].  
 
A.3.2.3  The bulb B, which the liquid  enters at the base of capillary is for the purpose of allowing some 
liquid to discharge from the upper reservoir A and thus the diameter of the meniscus in this bulb is large 
throughout the test. This reduces errors due to loading and surface tension corr ections.  
 
  
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Fig 2: U -Tube viscometer  
 
(All dimensions in millimetres)  
 
 
A.3.3  Calculation  
 
A.3.3.1  Calculate the kinematic viscosity in centistokes from each efflux time by the formula given 
below. The viscosities so calculated separately for each bulb should agree:  
                            V = Ct  
Where  
           V is the kinematic viscosity in ce ntistokes,  
           C is the determined calibration constant for the instrument (see clause  
            A.3.4), and  
           t is the time of flow in seconds.  
 
A.3.3.2  Calculate the dynamic viscosity in centipoises from the following:  
Dynamic viscosity in cp = Kinematic viscosity in cs x specific gravity (see clause A.2.5).  
 
A.3.4  Determination of Calibration Constant  
 
A.3.4.1  Unless the calibration constant is already known, calibrate the viscometer using, as primary 
standard, oil samples the viscosities of which have been determined by the recognized laboratory . 
 
A.3.4.2  Determine, in the viscometer being calibrated, the flow time of the appropriate standard, which 
shall not be less than 200 sec . 
 
A.3.4.3  Then calculate the calibration constant C, by substituting in the equation under Clause A.3.3.1 
the flow time and the kinematic viscosity of the oil.  
 
A.3.4.4  The calibration constant shall be determined at a temperatu re of 30 °C ± 0.2 °C. 
 
A.4 Determination of moisture  
 
A.4.0 Principle  
The material is heated under reflux with an organic liquid, which is immiscible with water. The carrier 
liquid distils into a graduated receiver carrying with it water, which then separates to form lower layer, 
the excess carrier liquid overflowing from th e trap and returning to the still.  
 
 
 
 
 
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 A.4.1  Apparatus  
The apparatus commonly known as ‘Dean Stark Apparatus’ consists of a glass flask heated by a 
suitable means and provided with a reflux condenser discharging into a trap and connected to the flask. 
The connections between the trap, the condenser and the flask should be interchangeable ground glass 
joints. Alternatively, ordinary flask may be used with ungrounded receiver end. The trap serves to collect 
and measure the condensed water, and to r eturn the solvent to the flask. The assembly of the apparatus 
is shown in Fig. 3 and various components are described under clauses A.4.1.1 to A.4.1.5.  
 
A.4.1.1  Flask  – A 500 -mL to 1 000-mL flask of the shape shown in Fig.3, made of heat resistan t glass, 
well-annealed and as free as possible from striate  and similar defects.  
 
 
 
Fig 3: Assembly of moisture distillation apparatus  
 
(All dimensions in millimetres)  
 
A.4.1.2  Condenser  – Condenser shall be a glass water -cooled reflux type, of the design and dimensions 
shown in Fig. 4A. The only mandatory dimensions for the condenser are the external diameters of the 
inner tube and of the jacket, which shall be 16  -17 mm and 23 -25 mm respectively. The joints A and B 
shall be neatly finished as show in Fig. 4A, particularly the bore at B shall have the minimum 
disturbance. The shoulder above the cone of joint D shall be elongated as shown in Fig. 4A to avoid a 
sharp re-entrant shape which may restrict the free flow of liquid down the inner wall. The cone shall be 
extended beyond the length appropriate to the joint D, and the lower end ground at an angle of 
approximately 60 ° to the axis. The drainage tip shall be at th e front of condenser when the lower water 
connection is to the left, and the finish shall be either smooth o r fire-polished. When inserted into the 
trap, the tip of the condenser shall be 6  mm to 7 mm above the surface of the liquid in the trap after 
distillation conditions have been established. The nominal dimensions of the joint d are given below:  
 
Nominal diameter of large end 
of ground zone  Nominal diameter of small end 
of ground zone  Nominal length of ground zone 
measured axially  
mm mm mm 
18.8 16.2 26 
 
 
 
© TBS 2020   Second Edition 2020  
 
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Fig 4A: Condenser   
 
(All dimensions in millimetres)  
 
 
A.4.1.3  Receiver  (Trap) –, is made up of heat resistan t glass, well annealed an d as free as possible 
from striate  and similar defects, pro vided with ground glass joints as shown in Fig. 4B, consisting 
essentially of the upper chamber, together with the tube and ground joint leading to the flask, and the 
graduated tube.  
 
The receiver shall be of 2 -mL capacity. The mandatory dimension’s  tolerances for the receiver shall be 
as given in Table 2.  
 
 
 
FIG 4B: Receiver showing alternate connections to the distillation vessel  
 
(All dimensions in millimetres)  
 
Table 2 - Mandatory dimensions and tolerances for receiver  
 
SL. No.                        Characteristics               Receiver  
1. Volume, equivalent to smallest subdivision, mL                     0.05 
2. Scale length, mm                   95 ±10  
3. Length of cylindrical tube above upper graduation 
mark, mm                    10-15 
4. Tolerance on capacity , mL                   ± 0.02 
 
 
© TBS 2020   Second Edition 2020  
 
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 The graduated portion of the receiver shall be cylindrical throughout its length. The bottom of the 
graduated tube of the receiver shall be sealed, the end of the tube being appro ximately hemispherical 
in shape . The graduation marks shall be fine, clearly etched permanent lines of uniform thickness lying 
in planes at right angles to the axi s of the tube. The graduation marks shall be confined to the cylindrical 
portion of the tube and there shall be no evident irregularity in their spacing. In these receivers, the 
numbered graduation marks shall be carried completely round the tube, the shor test graduation marks 
shall be carried halfway round the tube, and the graduation marks of intermediate length shall be carried 
approximately two -thirds of the way round the tube and shall project equally at each end beyond the 
shortest graduation marks.  
 
The capacity corresponding to any graduation mark is defined as the volume of water at 27 °C, 
expressed in millilitres, required to fill the graduated portion to that mark at 27 °C, the axis of the 
graduated portion being vertical and the lowest point of t he water meniscus being set on the graduation 
mark.  
 
The error at any point on the receiver scale, and also the difference between the errors at any two points 
on the scale, shall not exceed the figures given for the receivers in Table 2.  
 
Each receiver sh all have permanent and legibl e marks on it:  
a) The abbreviation ‘mL’;  
b) The inscription ‘27 °C’ to indicate that the receiver is graduated for contents at 27  °C; and  
c) An identification number on the key.  
 
A.4.1.4  Heat Source  – The source of heat may be either an  oil bath or an electric heater provided with 
a sliding rheostat or other means of heat control. The temperature of oil in the bath shall not be very 
much higher than the boiling point of xylene or toluene, whichever solvent is used.  
 
A.4.1.5  Copper wire – It should be long enough to extend through the condenser, with one end twisted 
into a spiral. The diameter of the spiral shall be such that it fits loosely within the graduated portion, of 
the receiver and yet can be moved up and down.  
 
A.4.2  Reagents  
 
A.4.2.1  Potassium Dichromate  – Sulphuric Acid Cleaning Solution  
 
A.4.2.2  Xylene or Toluene  – Saturate the xylene or toluene by shaking with a small quantity of water, 
and distil. Use the distillate for the determination of moisture.  
 
A.4.3  Procedure  
 
A.4.3 .1 Clean the entire apparatus with potassium dichromate -sulphuric acid cleaning solution to 
minimize the adherence of water droplets to the sides of the condenser and the receiver. Rinse 
thoroughly with water and dry completely before using.  
 
A.4.3.2  Place  100 g of the material, accurately weighed, in the distillation flask and add an equal volume 
of the solvent xylene or toluene as desired. Assemble the apparatus and fill the receiver with the solvent 
by pouring it through the condenser until it begins to over-flow into the flask. Insert a loose cotton plug 
in the top of the condenser to prevent condensation of atmospheric moisture within the tube. In order 
that the refluxing may be under control, wrap the flask tube leading to the receiver with asbestos cl oth. 
Heat the flask to the distillation rate at 100 drops per minute. When the greater part of the water is 
distilled over, increase the distillation rate to about 200 drops per minute and continue until no more 
water is collected.  
 
Purge the reflux conde nser occasionally during the distillation with five millilitres -portions of xylene or 
toluene to wash down any moisture adhering to the walls of the condenser. The water in the receiver 
may be separated from the xylene or toluene by moving the spiral coppe r wire up and down in the 
condenser and receiver occasionally, thus causing the water to settle at the bottom of the receiver. 
Reflux until the water level in the receiver remains unchanged for 30 min  and then shut off the source 
of heat. Flush the condens er with xylene or toluene as required, making use of the spiral copper wire  
© TBS 2020   Second Edition 2020  
 
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 to discharge any moisture droplets. Immerse the receiver in water at about 27 °C for at least 15 min  or 
until the xylene or toluene layer is clear, and then read the volume of wate r. 
 
A.4.4  Calculation  
           
          Moisture, percent by mass = 100 VD  
                                                              M 
Where  
           V is the volume in mL of water,  
           D is the specific gravity of water at the temperature at whic h the volume of water is  
read,  
           M is the mass in g of the material taken for the test.  
 
A.5 Determination of matter insoluble in toluene  
 
A.5.1  Reagent  
 
- Toluene  
 
A.5.2  Procedure  – Weigh accurately 50 g of the well -mixed material into a conical flask and dissolve by 
warming on a water -bath, in four times its volume of toluene, the flask being loosely covered. Then filter 
the solution through a weighed sintered glass crucible (G No. 1), previously dried at 100  °C ± 2 °C. 
Transfer any insoluble residue to the crucible by means of additional toluene and wash the residue with 
toluene until a few drops of the filtrate yield no residue on evaporation. Dry the  crucible at 100  °C ± 2 
°C to a constant weight.  
 
NOTE: In place of sintered glass crucible, coun terpoised double filter papers (Whatman No. 5 of about 
150 mm in diameter may be used ). Reduce the two folded filter papers to equal weight by removing the 
apex of the heavier filter paper. Heat the two to a temperature of 100 ± 2 °C. For filtering, use the uncut 
paper inside the originally heavier paper so that the inner paper retains the separated material, yet both 
of them are equally subjected to any action exerted by the oil and toluene.  
 
A.5.3  Calculation  
           
          Matter insoluble in toluene  percent by mass , = 100 w  
                                        W 
Where 
           w is the loss in weight in g of the material upon heating, and  
           W is the mass in g of the material taken for the test.  
 
A.6 Determination of loss in weight upon heating  
 
A.6.1  Procedure  – Weigh accurately 100 g of the material in a 400 -mL beaker. Heat the beaker together 
with the material for 30 min  on an electric hot -plate maintained at 205  °C ± 5 °C and stir the material 
after every two minutes. At the end of this period, remove the be aker, allow it to cool to room 
temperature and weigh again.  
 
A.6.2  Calculation  
           
          Loss in weight upon heating , percent by mass = 100 w  
                                               W 
Where 
           w is the loss in weight in g of the material upon heating, and  
           W is the mass in g of the material taken for the test.  
 
A.7 Determination of ash  
 
A.7.1 Apparatus  
  
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 A.7.1.1  Porcelain crucible  
A.7.1.2  Muffle furnace  
 
A.7.2 Procedure  
 
Weigh an empty porcelain crucible (after being heated and cooled). Weigh exactly 1.5 g of the sample 
and put in the crucible above. Place the crucible containing sample was in a muffle furnace and 
incinerate at a temperature of 600 °C for 2 hours. Afterwards, remove the crucible with the content, cool 
in a desiccator and weigh. Calculate the percentage ash content (%Ash) using the following equation.  
 
A.7.3 Calculation   
 
Percentage ash content (%  Ash) = 𝑊𝑒𝑖𝑔 ℎ𝑡 𝑜𝑓 𝑐𝑟𝑢𝑐𝑖𝑏𝑙𝑒  𝑐𝑜𝑛𝑡𝑎𝑖𝑛  𝑠𝑎𝑚𝑝𝑙𝑒  − 𝑊𝑒𝑖𝑔 ℎ𝑡 𝑜𝑓 𝑒𝑚𝑝𝑡𝑦  𝑐𝑟𝑢𝑐𝑖𝑏𝑙𝑒
𝑊𝑒𝑖𝑔 ℎ𝑡 𝑜𝑓 𝑠𝑎𝑚𝑝𝑙𝑒 ×100%  
 
A.8 Determination of iodine value  
 
A.8.0  Principle  – The material is treated in carbon tetrachloride medium, with the known excess of 
iodine monochloride solution in glacial acetic acid (Wij’s solution). The excess of iodine monochloride 
is treated with potassium iodide and the liberated iodine determined  by titration with sodium thiosulphate 
solution.  
 
A.8 Wij’s Method  
 
A.8.1  Reagents  
 
A.8.1.1  Potassium dichromate  
 
A.8.1.2  Conc. H ydrochloric acid  
 
A.8.1.3  Potassium iodide solution  – Prepare a fresh solution by dissolving 10 g of potassium iodide free 
from potassium iodate, in 90 mL of water.  
 
A.8.1.4  Starch solution  – (See preparation in A.12)  
 
A.8.1.5  Standard sodium thiosulphate solution  – It shall be approximately 0.1 N.  
Dissolve 24.8 g sodium thiosulphate crystals (Na 2S2O3.5H 2O) in carbon dioxide free water  and make 
up to 1  000 mL. Store the solution in a cool place in a dark coloured stock bottle with a guard tube filled 
with soda lime . After storing the solution for about two weeks, filter if necessary and standardize it as 
prescribed below:  
     
Weigh accurately 5.0 g of finely ground potassium dichromate, which has been previously dried to a 
constant weight at 105 °C ± 2 °C into a cl ean one -litre volumetric flask. Dissolve in water, make up to 
the mark; shake thoroughly and keep the solution in a cool dark place. For standardization of sodium 
thiosulphate, pipette 25 mL of this solution into a clean glass stoppered 250 -mL conical flas k or bottle. 
Add 5 mL of concentrated hydrochloric acid and 15 mL of 10 percent potassium iodide solution. Allow 
to stand in the dark for 5 min  and titrate the mixture with the solution of sodium thiosulphate, using 
starch solution as an internal indicator  towards the end. The end point is taken when the blue colour 
changes to green. Calculate the normality (N) of the sodium thiosulphate solution as follows:  
                
Normality (N) of the sodium thiosulphate solution    =  25 W
49.03 V    
                                                      
Where 
           W is the mass in g of the potassium dichromate, and  
           V is the volume in mL of sodium thiosulphate solution required for the titration.  
          
 
  
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 A.8.1.6  Iodine crystals – Re-sublimed.  
 
A.8.1.7  Acetic acid  – It shall be glacial acetic acid, 99 percent and free from reducing impurities. Test 
for reducing impurities as follows:  
Dilute 2 mL of the acetic acid with 10 mL of water and add 0.1 N potassium permanganate solution and 
maintain at 27 ± 2 °C. The test shall be taken as having been satisfied if the pink colour is not discharged 
at the end of two hours.  
 
A.8.1.7  Chlorine gas  – It shall be dry.  
 
A.8.1.8  Iodine trichloride  (ICl 3) 
 
A.8.1.9  Iodine monochloride (ICl)  - It shall be 98 percent, assay . 
 
A.8.1.10  Wij’s iodine monochloride solution  – Prepare this solution using one of the following two 
methods, and store in a glass -stoppered bottle in a cool place, protected from light:  
 
i) Dissolve 13 g of iodine in one litr e of acetic acid, using gentle heat, if necessary, and 
determine the strength by titration with standard sodium thiosulphate solution. Set aside 50 
to 100 mL of the solution and introduce chlorine gas into the remainder until the 
characteristic colour chan ge occurs the halogen content is nearly doubled as ascertained 
again by titration. If the halogen content has been more than doubled, reduce it by adding 
the requisite quantity of the iodine -acetic acid solution. A slight excess of iodine does no 
harm, but  avoid an excess of chlorine.  
 
           Example:  
If the titration of 20 mL of original iodine -acetic acid solution  requires 22 mL of standard 
sodium t hiosulphate, then 20 mL of the Wij’s solution shall require between 43  and 44 mL 
(and not more than  
           44 mL) of the same sodium thiosulphate solution.  
 
ii) Dissolve 8 g of iodine trichloride in approximately 450 mL of acetic  acid Dissolve separately  
9 g of iodine crystals in 450 mL acetic acid, using heat, if necessary. A dd gradually the 
iodine solution to the iodine trichloride until the colour changes  to reddish brown.  Add 50 
mL more of iodine solution and dilute the mixture with acetic acid till 10 mL of the mixture 
is equivalent to 20 mL of  standard thiosulphate soluti on when the halogen content is 
estimated by titration in the presence of an excess of potassium iodide and water. Heat the 
solution to 100 °C for 20 min , and  cool. Prevent access of water vapour in preparing the 
solution.  
 
A.8.1.11 Carbon tetrachloride – It shall be inert to Wij’s solution.  
 
A.8.2  Procedure  – Take 50 g of the cashew  nut shell liquid in a 250 -mL beaker and heat slowly to 205  
°C ± 5 °C on an electric hot plate while stirring thoroughly to prevent violent foaming. As soon as th is 
temperature is reached cover the beaker and cool it undisturbed to room temperature. Filter the material 
through a filter paper to remove any impurities. Make sure that the glass apparatus used is absolutely 
clean and dry. Weigh accurately by difference  about 0.10 g to 0.12 g of the filtered material in a clean 
and dry 500 -mL iodine flask or well ground glass stoppered bottle to which 25 ml of carbon tetrachloride 
has been added and agitate to dissolve the contents. The weight of the sample shall be such  that there 
is an excess of Wij’s solution 50 to 60 percent of the amount added. Add 25 mL of the Wij’s solution 
and replace the glass stopper after wetting with potassium iodide solution; swirl for slow mixing, and 
allow standing in the dark for one hour.  Carry out a blank test simultaneously under similar experimental 
conditions. After standing, add 15 mL of potassium iodide solution and 100 mL of water, rinsing in the 
stopper also, and titrate the liberated iodine with standard sodium thiosulphate soluti on, swirling the 
contents of the bottle continuously to avoid any local excess until the colour of the solution is straw 
yellow. Add one millilitre of the starch solution and continue the titration until the blue colour formed 
disappears after thorough sha king with the stopper on.  
 
A.8.3  Calculation   
© TBS 2020   Second Edition 2020  
 
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           Iodine value =   12.69 (B−S)N
W                              
                                                                           
Where , 
           B is the in mL of the standard sodium thiosulphate solution required for the blank,  
           S is the in mL of the standard sodium thiosulphate solution required for the sample,  
           N is the normality of the standard sodium thiosulphate  solution, and  
           W is the mass in g of the material taken for the test.  
 
A.9 Determination of polymerization time  
 
A.9.0  Principle  – It is the time taken by de -hydrated cashewnut  shell liquid to gel after the addition of 
concentrated sulphuric acid in diethyl sulphate.  
 
A.9.1  Reagents  
 
A.9.1.1  Concentrated sulphuric acid  
 
A.9.1.2  Diethyl sulphate  
 
NOTE: Diethyl sulphate is poisonous should be handled with care.  
 
A.9.2  Procedure  
 
A.9.2.1  Dehydration of Material  – Pour 50 g of the material into a 250 -mL beaker and heat slowly to 
205 ± 5 °C with continuous stirring till foaming ceases.  
 
A.9.2.2  Polymerization Test – Take 5.0 ± 0.1 g of the dehydrated oil into a 150 mm x 15 mm test -tube. 
Add through a dropping pipette 0.5 mL of 25 percent solution (v/v) of concentrated sulphuric acid in 
diethyl sulphate and stir the mixture thoroughly with a glass rod of three millimetres in diameter and 
rounded at the end. Make sure tha t a thorough mixture is obtained after the addition of the sulphuric 
acid-diethyl sulphate solution, to avoid local resin formation, which would alter the result. Insert the tube 
into an oil bath, which has been heated to 176  °C ± 1 °C, and note the time o f insertion with a stopwatch. 
Stir the material slowly. It will be noted that the sample becomes more and more viscous. Note the time 
when the material suddenly ‘gels’ or sets to a stiff rubbery pasty mass or a dry rubbery mass. Report 
the time taken as th e polymerization  time.  
 
A.10 Determination of polymerization by viscosity method  
 
A.10.0  Principle  – It is determined by finding out viscosity of the material when mixed with diethyl 
sulphate and kept in an oven at 185 °C ± 1 °C, for one hour and finally d issolved in xylene.  
 
A.10.1.2  Diethyl sulphate  
 
NOTE: Diethyl sulphate is poisonous should be handled with care.  
 
A.10.1.3  Xylene  
 
A.10.2  Procedure – Take approximately 500 g of the material in a 1  000-mL beaker or flask. Add 200 
mL of dilute sulphuric acid and mix thoroughly. Heat the solution on a water -bath maintained at 90 °C 
to 95 °C for five minutes and then separate the two layers by any suitable method. The separation may 
best be achieved by centrifuging the hot mixture. Transfer this mixture to the separating funnel and 
allow it to stand for ten minutes. Discard the lower aqueous layer and collect the upper layer of the 
cashewnut shell liquid from the separating funnel. Repeat treatment of th e separated CNSL layer with 
sulphuric acid and separate the two layers. Add 200 mL of water to the separated CNSL, mix thoroughly 
and heat the mixture to 90  °C to 95 °C for five minutes. Separate the layers by centrifuging or by any 
suitable method. Test t he pH of this aqueous layer. If the pH of the aqueous layer is below five, repeat 
the treatment of the above separated CNSL layer with further quantity of 200 mL of water till the pH of  
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 the aqueous layer obtained is 5. Weigh 200 g of the CNSL into a 500 -mL beaker and add 8 g of diethyl 
sulphate. Reweigh the beaker and the contents. Mix the contents thoroughly and place the beaker in 
an oven maintained at 185 °C ± 1 °C for one hour. Remove the beaker from the oven and add 200 mL 
of xylene. Mix well and cool to room temperature. Make up for any loss in xylene so as to have 200 g 
of xylene in the mixture. Determine the viscosity of the solution at 30 °C ± 0.2 °C by using the U -tube 
viscometer as prescribed in A.3 or any other suitable viscometer.  
 
 
A.11 Determination of polymerization time  Refractive index  
A.11.1  Apparatus  
A.11.1.1  Refractometer analyzer  
A.11.1.2  Syringe  
 
A.11.2  Procedure  
 
Start with calibration of the analyzer then using syringe inject 0.9 mL of Cashewnut shell liquid sample 
into the port . Afterwards, start the system and note the result ; determined the result s in replicate 
measurements.  
 
 
A.12 Preparation of Starch Solution  
A.12.1 Introduction  
This procedure contains two recipes for preparing starch solution —the traditional method and the spray 
starch method. With the traditional method, soluble starch is added to boiling water. The spray  starch 
method simply requires spraying spray starch into a container of water.  
 A.12.2  Materials  
A.12.2.1 Traditional Method  
Soluble starch,  
Water, distilled or deionized,  
Balance  
Beaker, 250 -mL  
Graduated cylinder, 100 -mL Stirring rod  
Hot plate  
 
A.12.2.2 Spray Starch Method   
Spray starch (the type used for ironing)  
Water,  
Beaker, 250 -mL 
Graduated cylinder, 100 -mL 
Stirring rod   
Note -1:  
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 Safety Precautions  
This activity requires the use of hazardous components and/or has the potential for hazardous reactions. Avoid 
spraying starch onto the floor as this may cause the floor to become slippery. Avoid spraying starch in the direction 
of anyone’s face or eyes. Wear chemical splash goggles, chemi cal-resistant gloves, and a chemical -resistant 
apron. Please review current Material Safety Data Sheets for additional safety, handling, and disposal information.  
A.12.3 Procedure  
A.12.3.1 Traditional Method for preparing 100 mL of a 1% starch solution.  
1. Place 100 mL of distilled or deionized water in a 250 -mL beaker and bring to boiling on a hot plate.  
2. Make a smooth paste with 1 g of soluble starch and a small volume (severa l milliliters or so) of distilled 
or deionized water.  
3. Once the water is boiling, carefully remove the beaker containing the boiling water from the hot plate. 
Pour the starch paste into the boiling water and stir until all of the starch is dissolved. Th e resulting 
solution may be somewhat cloudy.  
4. Allow the starch solution to cool to room temperature before use. Note: This is especially important 
if the starch solution is to be used in a kinetics experiment where temperature is a factor.  
A.12.3.2 Spray Starch Method for preparing 100 mL of a starch solution.  
1. Pour 100 mL of distilled or deionized water into a 250 -mL beaker.  
2. Generously spray the spray starch into the water. Spray until the solution appears slightly blue in 
color (at least 10 seconds).  
3. Stir the solution to mix and allow the foam to settle. This may take up to 10 minutes.  
Note -2: 
• Starch solutions, prepared by either method, have a poor shelf life and will deteriorate quickly. Therefore, a fresh 
starch solution sho uld be prepared on the day of the lab.  
• Starch solutions are often used as indicators for detecting the presence of iodine. Generally, a 1% starch solution 
will produce a nice, deep -blue colour in the presence of iodine. The more concentrated the starch solution, the 
deeper blue in colour is the resulting solution. If the starch solution is too dilute (which may occur when a starch 
solution is prepared by the spray starch method), a colour change will still be observed in the presence of iodine; 
however, the colour produced is more of a brown colour. If this brown colour is observed, simply spray more spray 
starch into the starch solution to make it more concentrated so that the familiar deep -blue colour is observed.  
 
 
 
 
 
 
 
 
 
 
 
 
 
  
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 Annex B  
 
(Normative)  
 
 
Sampling of cashew nut shell liquid (CNSL)  
 
 
B.1 General requirements of sampling  
In drawing samples,  the following precautions a nd directions shall be observed:  
 
B.1.1  As the material is vesicant;  care should be taken in opening the drums for sampling.  
B.1.2  Samples shall not be taken in an exposed place.  
B.1.3  The sampling instruments shall be clean and dry when used.  
B.1.4  Precautions shall be taken to protect the samples, the material being samp led, the sampling 
instruments and the containers for samples from adventitious contamination.  
B.1.5  The samples shall be placed in clean, dry and air -tight glass or other suitable containers on which 
the material has no action.  
B.1.6  The sample container s shall be of such size that they are almost completely filled by the sample.  
B.1.7  Each sample container shall be sealed after filling and marked with full details of sampling, the 
date of sampling and the month and the year of manufacture of the material.  
B.1.8  All sampling instruments, if made of copper, brass or bronze, shall be nick el plated.  
 
B.2 Sampling instruments  
 
 
 
 
 
 
FIG. 5: Sampling bottle or can  
 
B.2.1  Sampling bottle or can (see Fig. 5) – This instrument is suitable for taking samples from various 
depths in tanks. It consists of a weighed bottle or a metal container with removable stopper or cap, to 
which is attached a suitable chain, pole or code. This device is lowered to the various desired depths 
at which the stopper is removed and the container is allowed to fill.  
 
 
 
 
 
 
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All dimensions in millimetres  
 
Fig. 6: Open type sampling tube  
 
B.2.2  Open type sampling tube (see Fig. 6) – It is made of metal or thick glass and may be of 20  mm 
to 40 mm diameter and 400  mm to 8 000 mm in length (see Note). The upper and lower ends are 
conical and narrow down to 5 mm to 10 mm diameter. Handling is facilitated by two rings at the upper 
end. For taking a sample, the instrument is first closed at the top with a thumb or a stopper and  lowered 
until the desired depth is reached. It is then opened for a short time to admit the material, and finally 
closed and withdrawn.  
 
NOTE: For small containers, the size of the sampling tube may be altered suitably.  
 
B.3 Scale of sampling  
 
B.3.1  Lot – In a single consignment, all the containers of the same size and drawn from the same batch 
of manufacture shall constitute a lot. If a consignment is known to consist of containers of different sizes 
or of different batches of manufacture, then the contai ners belonging to the same size and batch of 
manufacture shall be grouped together and each such group shall constitute a separate lot. In case the 
consignment is in tanks, the tanks belonging to the same batch of manufacture shall constitute a lot.  
 
B.3.1.1  For ascertaining the conformity of the lot to the requirements of the specification, tests shall be 
carried out for each lot separately.  
 
B.3.2  Sampling from containers  – The number ( n) of the containers to be selected for sampling shall 
depend on the size ( N) of the lot and shall be in accordance with Table 3. In case of very small lots 
where the selection of three containers may be uneconomical, the method of judging the conformity of 
the lot to the requirements of the specification shall be as agreed to between the purchaser and supplier.  
 
Table 3: Scale of sampling for containers  
 
                 Size of the lot  Number of containers to be selected  
                          N                            n 
                    Up to 20                             3 
                    21  ‘’  40                             4 
                    41  ‘’  80                             5 
                    81  ‘’  120                             6 
                  121  ‘’  200                             8 
                  201 and above                            10 
 
 
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 B.3.2.1  The containers shall be selected at random and ensure the randomness of selection, random 
number tables may be used. In case, such tables are not available, the following procedure may be 
adopted:  
 
Starting from any container, count them in one order as 1 ,2,3,…., e.t.c, up to r and so on, where r 
is the integral part of N/n (N being the lot size and n the number of containers to be selected). Every 
rth container thus counted shall be withdrawn to give sample for test.  
 
B.3.3  Sampling from tanks – Each tank  in the lot shall be sampled separately for determining the 
conformity of the lot to the requirements of the specification.  
 
B.4 Preparation of test samples  
 
B.4.1  Test samples from containers  – To ensure that the samples taken from each container are fair ly 
representative, the contents shall be mixed thoroughly by shaking or stirring or rolling. Draw small 
samples of the material from various depths with the help of the sampling tube (see Fig. 6). The 
approximate quantity of the material to be drawn from a  container shall nearly be equal to thrice the 
quantity required for the test purposes.  
 
B.4.1.1  Out of the material drawn from individual containers, a small but equal quantity of material shall 
be taken and thoroughly mixed to form a composite sample, sufficient for carrying out triplicate 
determinations for all the characteristics. The composite s ample shall be divided into three equal parts, 
one for the purchaser, another for the supplier and the third for the referee.  
 
B.4.1.2  The remaining portion of the material from each container shall be divided into three equal parts, 
each forming an indivi dual sample. One set of individual samples representing the n containers selected 
shall be for the purchaser, another for the supplier and the third for the referee.  
 
B.4.1.3  All individual and composite samples shall be transferred to separate sample con tainers. These 
containers shall then be sealed airtight with stoppers and labelled with full identification particulars given 
in clause B.1.7.  
 
B.4.1.4  the referee samples, consisting of a composite sample and a set of n individual samples, shall 
bear the seals of both the purchaser and the supplier. They shall be kept at a place agreed  between 
the two, to be used in case of any dispute.  
 
B.4.2  Test samples from tanks  
 
B.4.2.1  For drawing a sample from a tank, lower the closed sampling bottle or can (see cl ause B.2.1) 
slowly to the required depth, open and fill it at that depth. Three samples shall be obtained at levels of 
one-tenth of the depth of the liquid from the top surface (top sample), one -half of the depth (middle 
sample) and nine -tenths of the dept h of the liquid from the top surface (lower sample). All the three 
samples thus obtained from a tank shall be mixed together in a clean dry container and shall be divided 
into three equal parts, one for the purchaser, another for the supplier and the third  for the referee. Each 
tank in the lot shall be sampled in the same manner as described above . The approximate quantity of 
the material to be drawn from a tank shall nearly be equal to thrice the quantity required for carrying out 
tests for the requirement  prescribed in this standard.  
 
B.4.2.2  All the samples thus obtained from tanks in the lot shall be transferred to separate containers. 
These containers shall be sealed airtight with stoppers and labelled with identification particulars given 
in clause B.1 .7. 
 
B.4.2.3  The referee test samples, consisting of the samples from the tanks in the lot, shall be kept at a 
place agreed between purchaser and supplier  in case of any dispute.  
 
B.5 Number of tests  
 
B.5.1  For samples from containers  
  
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 Test for the determination of iodine value shall be conducted on each of the individual samples 
separately.  
 
B.5.2  For samples from tanks  – Tests for the determination of all the characteristics in the specification 
shall be conducted on the samples from different tank s separately.  
 
B.5.3  Criteria for conformity  
 
B.5.3.1  For containers  
 
B.5.3.1.1  For individual samples – For iodine value, which shall be determined on the individual 
samples, the mean ( x̄) and range (R) of the test results shall be calculated as follows:  
 
          Mean ( x̄) = the sum of the test results  
                             number of the test results  
 
         Range (R) = the difference between the maximum and the minimum  
                              Values of the test results  
 
NOTE: For declaring the conformity of the lot to the requirement of iodine value, the value of the expressions 
(X – 0.6R) as calculated from the relevant test, results shall not be less than 250 or 375, as the case may be.  
 
B.5.3.1.2  For composite samples  – For declaring the conformity of the lot to the requirements of all the 
other characteristics determined on the composite samples, the test results for each of the characteristic 
shall satisfy the relevant requirements given in the specification.  
 
B.5.3.2  For tanks  
 
The lot shall be declared as conforming to the specification requirements of various characteristics, if 
each of the test results satisfies individually the relevant requirements specified in the standard.