IS 101 (Part 8/Sec 5) : 1993(Reaffirmed 1999)

Edition 4.1(1994-10)

Indian Standard

METHODS OF SAMPLING AND TEST FOR PAINTS, VARNISHES AND RELATED

PRODUCTSPART 8 TESTS FOR PIGMENTS AND OTHER SOLIDS

Section 5 Lead Restriction Test

( Third Revision )(Incorporating Amendment No. 1)

UDC 667.612 : 543 : 546.815

BIS 2002

B U R E A U O F I N D I A N S T A N D A R D SMANAK BHAVAN, 9 BAHADUR SHAH ZAFAR MARG

NEW DELHI 110002

Price Group 2

Paints (Other than Industrial Paints) and Allied Products Sectional Committee, CHD 020

FOREWORDThis Indian Standard (Third Revision) was adopted by the Bureau of Indian Standards, after thedraft finalized by the Paints (Other than Industrial Paints) and Allied Products SectionalCommittee had been approved by the Chemical Division Council.This standard (Part 8/Sec 5) is one of a series dealing with methods of sampling and test for paints,varnishes and related products. In this third revision three test methods have been prescribed fordetermination of lead in lead restricted paints. Any of the three methods can be used, but in case ofdispute, Electrolysis Method being the referee method shall be followed. This standardsupersedes clauses 28 and 29 of IS 101 : 1964 Method of test for ready mixed paints and enamels( second revision ).This edition 4.1 incorporates amendment no. 1 (October 1994). Side bar indicates modification ofthe text as the result of incorporation of the amendments.In reporting the result of a test or analysis made in accordance with this standard, if the finalvalue, observed or calculated, is to be rounded off, it shall be done in accordancewith IS 2 : 1960 Rules for rounding off numerical values ( revised ).

IS 101 (Part 8/Sec 5) : 1993

1

Indian Standard

METHODS OF SAMPLING AND TEST FOR PAINTS, VARNISHES AND RELATED

PRODUCTSPART 8 TESTS FOR PIGMENTS AND OTHER SOLIDS

Section 5 Lead Restriction Test

( Third Revision )1 SCOPEThis standard (Part 8/Sec 5) prescribesmethods of test for lead restriction and freedomfrom lead in paint and allied products. For leadrestriction test any one of the following threemethods may be used:

a) Electrolysis method;b) Molybdate method; andc) Sulphide method.

1.1 Electrolysis method shall be used as areferee method in case of any dispute.

2 LEAD RESTRICTION

2.1 Electrolysis Method

2.1.1 ProcedureTransfer about 5 g of well mixed paint to atared evaporating dish and dry at 105C toconstant mass. Place the exact mass of thedried sample in a muffle furnace and ash itfor 20 min, at 315C, 40 min at 425C and 1 hat 540C. Cool in a dessicator. Extract the ashin a 250 ml beaker with 30 ml conc nitric acidand 80-ml water and heat to boil. Filter intoa 400-ml beaker using fine texture paper toprevent manganese dioxide from passing intothe filtrate. Wash with water.Dilute the filtrate to approximately 300 ml,add 20 ml of 20 percent solution of ammoniumnitrate and 10 ml of 0.1 percent coppersulphate solution.Heat nearly to boiling and electrolyse usingplatinum gauze anode that has been weighedpreviously.Electrolyse for 15 min each at 1A, 2A and thenat 3A current. Rinse the electrode three timesin water with the current still on. Then removethe anodes, rinse in alcohol, dry for 15 min inan oven at 105 5C. Cool and weigh.

NOTE The electrodes should be cleaned after eachdetermination. This is best done by placing them in

nitric acid solution (1 : 4) that contains a few ml ofconcentrated hydrogen peroxide (H2O2, 30 percent),rinsed with water and dried for next use.

2.1.2 CalculationLead, percent by masson non-volatile vehicle =

whereM = mass, in g, of lead oxide PbO2, andW = mass of non-volatile vehicle taken.

2.2 Molybdate Method

2.2.0 Outline of the Method

Paint is digested with concentrated sulphuricacid and nitric acid in order to convert lead tolead sulphate followed by extraction withammonium acetate. Finally lead is precipitatedas lead molybdate and weighed as leadmolybdate.2.2.1 Procedure

Transfer about 5 g of well mixed paint toa 400 ml beaker and dry at 105C. Weighaccurately, add 20 ml of concentrated nitricacid and 15 ml of concentrated sulphuric acidand digest in order to remove all organicmaterial and change lead to lead sulphate.Remove traces of nitric acid by repeated fumingwith sulphuric acid. Cool, add 50 ml of water,heat to dissolve the salts and add 50 ml of ethylalcohol and set aside for several hours. Filterthrough a paper pulp pad and wash with dilutesulphuric acid ( 1 : 20 v/v ) containing10 percent of ethyl alcohol. Dissolve the leadsulphate in three 10-ml portions of hot20 percent ammonium acetate solution,followed by several washings with hot water.Treat the combined filtrate and washings with2 ml of glacial acetic acid, heat to boil, add10 ml of 5 percent aqueous ammoniumparamolybdate solution and boil for a fewminutes until the lead molybdate precipitatehas coagulated.

M 0.866 23 100W

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IS 101 (Part 8/Sec 5) : 1993

2

Filter through a porcelain filtering crucibleand wash with ammoniacal 2 percentammonium nitrate solution. Heat to dullredness at 600-650C to constant mass.2.2.2 Calculation

Lead content,percent by mass onnon-volatile matter =

whereW = mass of lead molybate, andS = mass of dry sample taken for test.

2.3 Sulphide Method

2.3.0 Outline of the Method

Determination of lead in lead restricted paintsis carried out by precipitating the lead assulphide from the separated pigment, which isfinally oxidized to lead sulphate.

2.3.1 Procedure

Shake about one gram of the ground pigmentobtained after treatment of paint as prescribedin IS 101 (Part 8/Sec 2), accurately weighed,continuously for one hour at room temperaturewith 1 000 times its weight of an aqueoussolution of hydrochloric acidcontaining 0.25 percent by mass of hydrogenchloride. Allow the mixture to stand for onehour and then filter. Precipitate the lead saltcontained in the clear filtrate as lead sulphide,filter, heat the lead sulphide in air to convert itinto lead sulphate, weigh, calculate as leadmonoxide (PbO) and express the result aspercentage on the dry weight of the materialtaken for test.

2.3.2 Calculation

Lead (as PbO) =

whereM1 = mass, in g, of the precipitate; andM = mass, in g, of the sample taken for the

test.

3 FREEDOM FROM LEAD

3.0 Outline of the Method

Determination of lead in lead-free paints iscarried out by treating the ash of the paint withnitric acid and then with ammonium acetatesolution, and precipitating lead as leadsulphide and finally oxidizing to lead sulphate.

3.1 Reagents

3.1.1 Dilute Nitric Acid Lead-free,approximately 4 N.

3.1.2 Ammonium Acetate Solution Lead-free, 10 percent m/v.3.1.3 Concentrated Sulphuric Acid Lead-free, sp gr 1.84.3.1.4 Dilute Sulphuric Acid 2 percent,obtained by dissolving 11 ml of concentratedsulphuric acid in one litre of water.3.1.5 Ammonium Acetate Solid, lead-free.3.1.6 Hydrogen Sulphide Gas, from Kippsapparatus.3.1.7 Hydrogen Sulphide Water Saturatedsolution.3.2 Procedure

Weigh 50 g of the material in a silica basin, andash it carefully until only slight traces of carbonremain. The temperature of the basin shall notbe allowed to rise above faint red heat, as athigher temperatures some lead may be lost byvolatilization. Treat the ash so obtained withdilute nitric acid. The quantity of acid isimmaterial provided it is sufficient to extractthe soluble matter, but avoid too great anexcess since it has to be evaporated off. Allowthe basin to stand on a boiling water-bath for atleast three hours. In case a large quantity ofinsoluble residue is left, heat the basin on thewater-bath overnight. Decant off thesupernatant liquid through a filter paper andextract the insoluble residue again on a boilingwater-bath for one hour with dilute nitric acid.Filter through the same filter paper and washthe residue thoroughly on the filter paper withhot water. Treat the residue on the filter paperwith 10 ml of ammonium acetate solution, filterand wash again. Mix the filtrate and washingsin a 500-ml evaporating basin, add 2 ml ofconcentrated sulphuric acid and evaporate thecontents of the basin on a sand-bath till fumesappear. Add 100 ml of water to the basin andallow to stand on the boiling water-bathfor 15 minutes. Then dilute the contents toabout 150 ml and allow to stand overnight atroom temperature. Filter the insoluble matteron a No. 42 Whatman filter paper (9 cm) andwash thoroughly with dilute sulphuric acid.Transfer the filter paper and residue to a smallbeaker, cover with 20 ml of water, andadd 1 to 2 g of ammonium acetate. Heat thebeaker on the water-bath for not less than halfan hour, stirring the contents occasionally.Decant the liquid through No. 42 Whatmanfilter paper (9 cm). Repeat the extraction withwater and ammonium acetate. Transfer all theinsoluble matter including the filter pulp to thefilter and wash throughout with warm watercollecting the filtrate and washings in a 150-mlbeaker. Pass hydrogen sulphide through the

0.564 36 WS

----------------------------------- 100

M1M--------- 100

IS 101 (Part 8/Sec 5) : 1993

3

liquid for 10 to 15 minutes and filter theprecipitated lead sulphide at once through aNo. 40 Whatman filter paper (9 cm). Washthoroughly but quickly with hydrogen sulphidewater keeping the residue on the filter paper, ifany, covered with liquid till washing iscompleted. Transfer the precipitate and filterpaper to a tared silica crucible. Dry, carefullyignite to sulphate, cool and weigh.

3.3 Alternatively, determine the quantity oflead by either of the following methods:

a) By electrolysis after dissolving theprecipitated lead sulphide in nitric acid, or

b) By polarographic method.3.4 Calculation Calculate as lead (Pb) andexpress the result as percent of the mass of thematerial taken for test.

Standard Mark

The use of the Standard Mark is governed by the provisions of the Bureau of IndianStandards Act, 1986 and the Rules and Regulations made thereunder. The Standard Mark onproducts covered by an Indian Standard conveys the assurance that they have been producedto comply with the requirements of that standard under a well defined system of inspection,testing and quality control which is devised and supervised by BIS and operated. by theproducer. Standard marked products are also continuously checked by BIS for conformity tothat standard as a further safeguard. Details of conditions under which a licence for the use ofthe Standard Mark may be granted to manufacturers or producers may be obtained from theBureau of Indian Standards.

Bureau of Indian Standards

BIS is a statutory institution established under the Bureau of Indian Standards Act, 1986 to promoteharmonious development of the activities of standardization, marking and quality certification of goods andattending to connected matters in the country.

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BIS has the copyright of all its publications. No part of these publications may be reproduced in any formwithout the prior permission in writing of BIS. This does not preclude the free use, in the course ofimplementing the standard, of necessary details, such as symbols and sizes, type or grade designations.Enquiries relating to copyright be addressed to the Director (Publications), BIS.

Review of Indian Standards

Amendments are issued to standards as the need arises on the basis of comments. Standards are alsoreviewed periodically; a standard along with amendments is reaffirmed when such review indicates that nochanges are needed; if the review indicates that changes are needed, it is taken up for revision. Users ofIndian Standards should ascertain that they are in possession of the latest amendments or edition byreferring to the latest issue of BIS Catalogue and Standards : Monthly Additions.

This Indian Standard has been developed from Doc : No. CDC 020 (0233)

Amendments Issued Since Publication

Amend No. Date of Issue

Amd. No. 1 October 1994

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Title PageForeword1. Scope2. Lead Restriction3. Freedom from LeadStandard Mark