Replacement for Synperonic N

Synperonic N: The Search for an Alternative
Andrew Wingham (1), John Fields, Frances Hartog and
Vincent Daniels (2)

Under the EC PARCOM directive 1992/8 nonylphenol ethoxylate
surfactants were to be phased out by 2000 for industrial purposes,
these included Synperonic N, widely used by the conservation
community in the UK.  The Victoria and Albert Museum and British
Museums identified the urgent need to research a suitable
replacement.

A working group (3) was set up and through consultations with
conservators, manufacturers and literature an initial list of 24
alternatives were identified (4).  Analysis of the data allowed a
refinement of this list to 11 feasible surfactants based upon
physical/chemical properties, environmental concerns, availability
and suitability.  The chosen 11 then proceeded to initial testing.

Lack of critical micelle concentration (CMC) data for the 11 chosen
surfactants delayed the process while the group carried out CMC
determination using Sugdena's Bubble Method at Imperial College.

Phase one testing began in August 2000 at The British Museum.
Commercially available, half-soiled samples of both cotton and wool
were obtained (5). Of the many defined soil compositions available
one was chosen that was thought to be most similar to that found on
historic textiles.  A wash/rinse programme was developed to
approximate normal conservation cleaning methods and samples of each
fabric were cleaned in this way using the surfactants at five times
their CMC.  Colour change of the clean and soiled regions was
measured along with pH and conductivity of the solutions from each
wash/rinse.

Initial results were obtained that account not only for cleaning
efficiency but soil redeposition onto clean areas.  A visual
assessment of the samples was carried out by two textile
conservators and gave a similar conclusion to that obtained using
instrumental measurements.  Using a combination of the results it
was possible for the group to select the five surfactants that would
continue to phase two testing: Dehypon LS45 (non-ionic), Hostapon T
(anionic), Imbentin C135/070 (non-ionic), Orvus WA (anionic) and
Synperonic 91/6 (non-ionic).

Phase two consisted of testing to investigate the effects of ageing
(light and thermal) on the tensile strength, also to monitor any
colour change during the ageing process.  Unsoiled samples were
washed manually again using surfactants at five times their CMC and
then subjected to six weeks simultaneous light (23.2-31-4 kLux) and
heat (53-58 deg. C) ageing.  Tensile testing revealed that although
there was a pronounced difference between the strength of the aged
and unaged samples there was no significant difference between
individual surfactants.  The colour measurements showed no extremes
of yellowing between washing in deionised water and in surfactant
solutions.

Having studied the scientific aspects of the surfactants it is now
ultimately up to the textile conservators to select which they feel
is the best and are most happy to use.  Some points have been noted
and include the extremely high foaming level for Orvus WA (anionic)
when washing, the slight odour and instant disappearance of foam
during the first rinse when using Synperonic 91/6 (non-ionic),
mildly cloudy solutions of Dehypon LS45 (non-ionic) caused by its
low cloud point (22 deg. C) and the extreme difficulty in dissolving
Imbentin C135/070 in solutions of water at 20 deg. C.  Dehypon LS45
(non-ionic) showed the best cleaning properties for both cotton and
woollen fabrics, closely followed by Hostapon T (anionic) and
Synperonic 91/6 (non-ionic).  Conservators should consider these
points when selecting their particular favourite from our list.

A full publication of this work will follow in due course and may
lead to further work in the field of surfactant research for
conservation purposes.

    1. Contact Information:
        Andrew Wingham
        1-3 High Street
        Biddenden, Kent TN27 8AL
        +44 1580 291025
        Fax: +44 870 137 1188
        Andrew [at] collectablegifts__net

    2.  Vincent Daniels
        Department of Conservation
        The British Museum, London WC1B 3DG
        +44 207 323 8679
        Fax: +44 207 323 8636
        vdaniels [at] thebritishmuseum__ac__uk

    3. Core working group consisted of Dr. John Fields (Conservation
    Scientist, British Museum), Frances Hartog (Textile Conservator,
    V&A) and Andrew Wingham (Conservation Science Student, V&A/BM).
    Dr. John Fields has now left the British Museum and Dr. Vincent
    Daniels filled his place for the remains of the project.

    4. Wingham, A., Unpublished Synperonic N: A Review of the
    Literature, 2000

    5. Manufacturer: Testafabrics  Supplier: Westlairds


                                  ***
                  Conservation DistList Instance 15:11
                  Distributed: Thursday, July 12, 2001
                       Message Id: cdl-15-11-003
                                  ***