Horn

Jason Clancy <g00067963 [at] gmit__ie> writes

>I am a furniture conservation student and am doing a research paper
>into horn, both as a veneer and as used in lanterns. For this paper
>I have to process the horn the traditional way; this is were i get
>stuck. I am having trouble flattening the horn. I am trying the many
>different ways that some of the old books say but they don't seem to
>work. I wonder is it because I am using Irish cows horn? If anyone
>out there has worked with horn before, your help will be very
>appreciated. I also need some help on staining the horn to imitate
>tortoise shell.

I haven't worked with horn, but with cattle hooves which is the same
material.  I haven't used the "improved method" discussed below.

The information below is taken from a text which I reprinted in
2000:

    Charles Holtzapffel
    Working Horn, Ivory and Tortoiseshell
    (originally published in 1843)
    2000, The Caber Press pp. 7,8,11

   "Our own supply of the horns of the ox and cow is insufficient
    for the numerous uses to which this substance is applied, and
    they are largely imported from Buenos Ayres and the Cape of Good
    Hope, and those of the bison and buffalo from the East Indies;
    the latter are sometimes very beautiful, and reserved for
    superior purposes. ...

   "The first step in operating upon horn is the separation of the
    bony core, which is effected by macerating the horns in water
    for about a month, then, from the putrefaction of the
    intermediate membrane, the core may be readily detached; this is
    not thrown away, but burnt to constitute the bone earth used for
    the cupels for assaying gold and silver.

   "The solid portion or tip of the horn is usually sawn off, and
    the remainder, if not cut into short lengths, is softened by
    immersion for half an hour in boiling water; it is then held in
    the flame of a coal or wood fire, until it acquires nearly the
    heat of melted lead, when it becomes exceedingly soft, after
    which it is slit up the side with a strong pointed knife, and
    opened out by means of two pairs of pincers applied to the edges
    of the slit; and lastly, the "flats" are inserted between iron
    plates previously heated and greased, which are squeezed tight
    in a kind of horizontal frame or press by means of wedges;
    wooden boards may be used.

   "For general purposes, as for combs, &c., the pressure should be
    moderate, otherwise, in the language of the workman, it breaks
    the grain, or divides the laminae, and causes the points of the
    teeth to split; but great pressure is purposely used in the
    manufacture of the leaves for lanterns, which are afterwards
    completely separated with a round-pointed knife, scraped and
    polished. The heat and pressure when applied to the light
    coloured horn also render it transparent.

    "An improved mode of 'opening horn' was invented by Mr. J. James,
    by which the risk of its being scorched or frizzled over the
    open fire is entirely removed; he employs a solid block of iron
    with a conical hole, and an iron conical plug: these are heated
    over a stove to the temperature of melted lead, and the horn,
    after having been divided lengthways with a saw or knife, is
    inserted in the hole, the plug is gradually driven in with a
    mallet, and in the space of about a minute the horn is softened
    and ready for being opened in the usual manner. ...

   "Horn is easily dyed by boiling it in infusions of various
    coloured ingredients, as we see in the horn lanterns made in
    China. In Europe it is chiefly coloured of a rich red-brown, to
    imitate tortoiseshell, for combs and inlaid-work. The usual mode
    of effecting this is to mix together pearl-ash, quicklime, and
    litharge, with a sufficient quantity of water and a little
    pounded dragon'sblood, and boil them together for half an hour.

   "The compound is then to be applied hot on the parts that are
    required to be coloured, and is to remain on the surface till
    the colour has struck; on those parts where a deeper tinge is
    required, the composition is to be applied a second time. This
    process is nearly the same as that employed for giving a brown
    or black colour to white hair; and depends on the combination of
    the sulphur, (which is an essential ingredient in albumen,) with
    the lead dissolved in the alkali, and thus introduced into the
    substance of the horn.  The horn which is naturally black is
    less brittle than that which is so stained."

Thompson Conservation Lab.
7549 N. Fenwick
Portland, Oregon  97217
USA
503-735-3942
Fax:  503-289-8723


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                  Conservation DistList Instance 19:28
                Distributed: Tuesday, November 29, 2005
                       Message Id: cdl-19-28-008
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