DRAFT ZANZIBAR NATIONAL STANDARD  
 
 
Seaweed  soap  — Specification  
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
ZANZIBAR BUREAU OF STANDARDS  
 
 
©ZBS 202 3- All rights reserved                                                                                             First edition  
 
 
 
PCD 508: 202 3 
 
                             
 PCD 508: 2023  
ii                                                                                                                ©ZBS 2023 - All rights reserved   
 
 
 Foreword  
 
This draft Zanzibar National Standard has been developed by the Chemical Products Standards 
Technical Committee (TCC1). In accordance with ZBS general procedures, this draft standard is 
presented to the public in order to receive any technical and editorial comment concerns  
 
In the preparation of this standard, assistance was derived from the following sou rces:  
 
ZNS 3, Toilet soap – Specification  
ZNS 67, Herbal soap – Specification  
 
Technical Committee Representatives  
 
This draft Zanzibar National Standard was prepared by the Chemical Products Standards Technical 
Committee which consists of representatives from the following organizations:  
 
Chief Government Chemist Laboratory Agency (CGCLA)  
Kisinga Youth and Women Foundation Centre (KYWFC)  
Ministry of Health (MOH)  
SUMAIT University  
Tanzania Bureau of Standards (TBS)  
Zanzibar Environment Manag ement Authority (ZEMA)  
Zanzibar Food and Drugs Agency (ZFDA)  
Zanzibar University (ZU)  
Zanzibar Bureau of Standards (ZBS) - Secretariat  
 
 
 
 
 
Zanzibar Bureau of Standards (ZBS)  
PO Box 1136  
Zanzibar  
Tel:  +255 24 2232225  
Fax: +255 24 2232225  
E-mail: info@zbs.go.tz  
Web: www.zbs.go.tz  
 
 
 
 
 
 
 
 
 PCD 508: 2023  
©ZBS 2023 - All rights reserved                                                                                                               1                                                                                                                                                                        
  
Seaweed  soap — Specification  
 
1 Scope  
This draft Zanzibar National S tandard specifies  requirements , sampling  and test methods for seaweed 
soap . It covers the following types  of soap : 
a) Seaweed bathing soap  
b) Seaweed liquid soap  
This standard does not apply to herbal soap.  
 
2 Normative references  
The following referenced documents are indispensable for the application of this draft Zanzibar 
National Standard. For dated references, only the edition cited applies. For undated references, the 
latest edition of the referenced document (including any amendments) applies.  
ISO 456, Surface active agents — Analysis of soaps — Determination of free ca ustic alkali   
ISO 457, Analysis of soap — Determination of Chloride content — Titrimetric method   
ISO 673, Analysis  of soap  — Determination  of ethanol  insoluble  matter  
ISO 684, Analysis of  soap — Determination  of total free alkali  
ISO 685, Analysis  of soap  — Determination  of alkali  content  and total fatty matter  content  
 
ISO 1067,  Analysis  of soap  — Determination  of unsaponifiable,  unsaponified  and unsaponified            
saponifiable matter  
TZS 35, Soaps  ― Sampling  and test methods  
ZNS 67, Herbal soap — Specification  
 
3 Terms and definitions  
For the purposes of this standard the (terms and) definitions given in TZS 35 and the following apply.  
3.1  
seaweed  
are marine macroalgae that grown in the sea. The term includes some types of Rhodophyta (red), 
Phaeophyta (brown) and Chlorophyta (green).  
3.2 
seaweed bathing soap  
soap  in the form of bar or cake  containing  seaweed parts and/or extracts which  is intended  for use in 
bathing  
 
3.3 
seaweed  liquid  soap  
soap  in the form of liquid  containing  seaweed  parts  and/or  extracts intended  for general hygienic 
purpose  PCD 508: 2023  
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 4 Requirements  
 
4.1 General requirements  
 
4.1.1  Seaweed bathing soap  
 
4.1.1.1  Seaweed bathing soap shall contain  non-harmful,  non-toxic and  non-irritant  substance  to 
human  being.  
 
4.1.1.2  Seaweed bathing soap shall have good lathering and cleansing properties  
 
4.1.1.3  In addition to perfumes  and moisture , seaweed  bathing soaps may contain coloring matter, 
preservatives and super fatting agents and such additional substances shall be declared on the label.  
 
4.1.1.4  The seaweed bathing soap production shall be cold or semi hot processed in order to protect 
the soap qualities.  
 
4.1.2  Seaw eed liquid soap  
 
4.1.2.1  The seaweed  liquid soap shall be in a form of a liquid or emulsion, opaque or transparent, 
coloured or  colourless  and perfumed  or unperfumed.  It shall be of uniform  consistency,  free from 
sediments  and suspended particles, be easily spreadable, have good lathering and rinsing properties, 
non-toxic and non - irritant.  
 
4.1.2.2  Seaweed  liquid  soap  may contain up to  2% appropriate  synthetic  detergents.  
 
4.1.3  Seaweed  parts and/or extract  
  
4.1.3.1  The manufacturer shall use quantity of seaweed parts and/or extract processed  in such a 
manner to ensure the intended application. The standard requires up to 1 0% of seaweed parts and/or 
extract in the blend . Objective evidence shall be made available to the inspector conducting the 
inspection work.  
 
4.1.3.2  If there are mixture of seaweed and other herbal ingredients, the requirement altogether shall 
not exceed 10% in the total blend.  
 
4.2 Specific requirements  
Seaweed  soap shall comply with the specific requirements specified in Table 1 when tested in 
accordance with the test methods specified therein.  
Table  1: Specific  requirements  for seaweed  soap  
 
 
S/No.   
Characteristics  
 Requirement   
Seaweed bathing 
soap  Seaweed liquid 
soap  Test method  
i.  Total  fatty matter,  % by  mass,  min. 70 15 ISO 685 
ii.  Matter insoluble in  alcohol, %  by 
mass,  max. 2.5 0.5 ISO 673 
iii.  Free caustic alkali  as (NaOH),  % 
by mass,  max.  
0.03  
0.03 ISO 456 
iv.  Total free alkali as Na 2O or K 2O, % 
by    mass,  max. - 0.03 ISO 684 PCD 508: 2023  
 
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 v.  Chloride content, as  NaCl, %  by 
mass,  max. 1.3 NIL ISO 457 
vi.  Unsaponified  fatty matter,  % by  
mass,  max. 0.5 NIL ISO 1067  
vii.  pH at 27  ºC - 7.5 – 9.5 Annex  A 
 
5 Packaging  
Seaweed soaps shall be packed in suitable materials that will not allow loss of important active 
ingredients, damage of the product or its contamination.  
6 Labelling  
The packages shall be securely closed, legibly and indelibly labelled in Kiswahili and/or English, and 
other language  as agreed  between  the manufacturer  and supplier  with the following  information:  
a) name of product as ‘Seaweed bathing soap ’ or ‘seaweed liquid soap’ ; 
b) manufactur er’s name and physical address;  
c) registered trade mark if any;  
 
d) country of origin;  
e) batch code or lot number;  
f) net content ; 
g) list of ingredients ;  
h) date of ma nufacture and best before date ; and  
i) percentage of seaweed used in total blend . 
 
7 Sampling  
For the purpose of this Zanzibar National Standard, sampling and criteria for conformity shall be done 
as specified in  ZNS 67 . 
 
 
 
 
 
 
 
 
 PCD 508: 2023  
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 Annex  A 
(Normative)  
Determination  of pH 
 
 
A.1 Methods  
The determination shall be carried out by the electrometric method or by the indicator method. In case 
of dispute  the electrometric method  shall be adopted.  
 
A.1.1 Electrometric  method  
 
Determination  shall be made  by using  a pH meter.  
 
Procedure  
 
Prepare a 1% solution ( m/v) of the material by weighing accurately about 5 g of the material and 
transfer it to a  150 ml beaker. Add about 50 ml of freshly boiled and cooled distilled water to the 
beaker and put the beaker on a  hot-plate for dissolving the material soluble in water. Continue stirring 
with a glass rod to ensure dissolution. Filter  through a filter paper into a 100 -ml flask. Wash the filter 
paper with hot water at least four times  and collect the  washings into the filtrate. Cool the solution 
under a water tap and then add distilled water up to the 100 -ml mark.  Determine  the pH of the solution  
using  a pH meter.  
 
A.1.2 Indicator  method  
 
A.1.2.1 Reagents  
 
Alizarin  yellow  R – pH range  10.1 to 12.0  and colour  change  yellow  to orange  
 
A.1.2.2 Procedure  
 
Prepare a solution as in A.1.1; take 10 ml of this solution in a glass test tube and add 0.5 ml of the 
indicator.  Compare the colour  produced with a series of buffer tubes on known pH in the range 10.0 to 
12.0. Report as pH,  the pH of the  buffer  solution which  gives  the closest  match with  the colour  
produced  by the sample.  
 
A.2 Standard  calibrated  glass  discs  may also be  used  for determination of pH.  
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 PCD 508: 2023  
©ZBS 2023 - All rights reserved