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and the labour charge for their application amounts to approximately ₤4 million.
By ensuring that materials of suitable quality are used, the savings in maintenance
must greatly exceed the cost of an advisory service. The work in this section is reviewed
regularly by an inter-departmental paint committee, on which all the departments
using or concerned with paint are represented.
Approved lists of manufacturers' brands of paint are maintained and during the
year 83 new brands were approved after test, while a further 84 were found not to be
of the quality required. Some of the more frequent causes of rejection were low opacity,
poor surface finish or hardness, low flexibility and presence in exterior paints of
lithopone or excessive amounts of chalk.
In addition to the laboratory examination of materials, visits were made to sites to
investigate defects arising from such causes as unsatisfactory preparation of surfaces or
manner of application of paint. Advice on many aspects of decorating has been made
available to all user departments. This has included assistance in questions of colour
matching, the establishment of standards and the recommendations for the painting
of a wide variety of materials under various adverse conditions.
Increased demands are being made on the facilities provided by the branch for the
examination of building materials. The range of materials received for assessment of
quality or investigation of possible faults included floorings, floor sealers and polishes,
plasters, light alloys and plastic building materials, fire retardants, concrete, slates,
asphalts and bitumen felts. In addition to laboratory tests, small scale practical trials
under normal conditions of use are frequently made, and sometimes accelerated
weathering tests are employed to assess the value of articles intended for external use.
Wherever applicable reference is made to British Standard Specifications in assessing
the quality of a product. Officers of the branch visited many sites to examine and advise
on problems at first hand and have thus maintained close contact with the practical
difficulties sometimes involved in the adoption of new methods and materials.
Examination was made of clays and ground waters from building sites. The importance
of tests on these samples has increased with the frequent use of high blocks of
flats in housing schemes. The deep concrete foundations of these flats may be in contact
with moist soil or ground water where sulphates normally present in London clay can
weaken Portland cement concrete. Estimation of the sulphate content in the soil enables
recommendations to be given as to the appropriate cement to use to resist aggressive
attack by sulphate in excessive concentrations.
Air pollution
The Council has for many years co-operated with the Department of Scientific and
Industrial Research in investigating the incidence of air pollution. Regular observations
are made at 20 sites, which include seven of the parks, five sites near hospitals, both
Council sewage outfall works, Kew Observatory and the grounds of King GeorgeV
Hospital at Godalming. Standard types of instrument are used and at a few of the sites
comparative records are available for a period of 35 years.
The instruments in use throughout 1956 were:
Seven deposit gauges for collection of matter settling from the atmosphere or washed down
by rain; these deposits are anlaysed monthly.
Ten lead peroxide cylinders for the comparative measurement of the amount of sulphur
dioxide in the air; the amount of peroxide converted to sulphate is found by analysis each month.
Three sets of volumetric apparatus for the dual measurement of smoke and sulphur dioxide;
this equipment normally requires daily attention.
Seven multiple-circuit sets of volumetric apparatus with which up to six consecutive samples
can be taken before the filters and solutions need to be examined and renewed. This automatic
sampler, devised in the laboratory, facilitates the study of peak concentrations of pollutants, and
enables detailed observations to be made covering night and weekend periods.
The observations made during the year again showed a marked difference between
rural and urban conditions, as did those in different localities within the County
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