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Celtic art in Pagan and Christian times

John Stuart Mill · en
Crosthwaite    (British Mus.)                  Cumberland.
    Middleton Moor (Sheffield Mus.)                Derbyshire.
    Over-Haddon                                    Derbyshire.
    Benty Grange                                   Derbyshire.
    Chesterton     (Warwick Mus.)                  Warwickshire.
    Caistor        (now lost)                      Lincolnshire.
    Oxford         (Pitt-Rivers Collection)        Oxfordshire.
    Needham Market (now lost)                      Suffolk.
    Barrington     (Sir John Evans’ Collection)    Cambridgeshire.
    Lullingstone   (Sir W. Hart Dyke’s Collection) Kent.
    Greenwich      (Mr. J. Brent’s Collection)     Kent.
    Kingston Down                                  Kent.

The hammer-headed pins, a list of which has already been given on page
108, are also instances of the use of Celtic enamel in post-Roman times.

       *       *       *       *       *

Before going further it may be as well to say a few words about the art
of enamelling in general, so as to show the position occupied by the
Late-Celtic examples.

The term enamel is used to designate a particular kind of mixture
or paste which can be applied to the surface of metals or other
materials, so that when it has been vitrified by the application of
heat, and afterwards cooled, it forms a decoration of great beauty and
durability. The base of all enamels is a flux composed of silica (in
the shape of silver sand or powdered flint), red lead, and potash.
To this flux are added certain metallic oxides to produce different
colours, and, if necessary, oxide of tin to render it opaque. The
materials are mixed together, fused in a crucible, reduced to a fine
powder when cold, made into a paste with water, and then applied to the
surface of metal to be decorated. After vitrifaction in a furnace and
polishing, the enamel is complete.

Mr. A. W. Franks[270] divides enamels into the following classes:—

[270] Afterwards Sir Wollaston Franks; see _Glass and Enamel_, by J. B.
Waring and A. W. Franks.

    (1) _Inlaid Enamel_, where the outlines are formed by
        metal divisions.
    (2) _Transparent Enamel_, where the outlines and all the
        markings are produced by variations of depth in the
        sculptured ground over which the vitreous material is
        floated.
    (3) _Painted Enamel_, where the outlines are made by a
        difference in the tint of the enamel itself, which
        completely conceals the metal base beneath.

The divisions between each of the colours in inlaid enamel are produced
in two different ways, namely:—