CHAPTER XVffl
GHATTNE-SIZIN^
THE best writing and typewriting papers, whether machine-made or hand-
made, are always 'sized', or coated and impregnated with a solution of gelatine,
in order that their surface may be more even and more resistant to ink.
Papers sized with a gelatine emulsion are freer from fluff and 'hairs' on
the surface, as these are all glued down among the other fibres and do not
become attached to the pen-nib. This glueing down does not, however,
take place with the coucher hairs from the felts, as these are wool and not
cellulose.
In the case of a gelatine-sized paper, the ink lies in the thin film of gelatine
and dries there, so that it may, if necessary, be erased and other letters or figures
substituted.
Papers are sometimes required to 'stand ink after erasure', which means
that they must be hard 'engine-sized5 before they are tub-sized. In this
case, when the paper has been hard-sized in the beater, less gelatine is taken up
in the same time, as it does not penetrate the sheet to such an extent, but lies
on the surface. The writing is easily erased, the gelatine being removed with
it, and more writing may be filled in without the ink 'running' to any great
extent.
Gelatine-sized papers are much more durable, as the fibres are protected
by the thin film from the oxidising agents of the atmosphere. They are also
rendered more tough and will stand folding and rough handling. The gelatine
also imparts other distinctive qualities to papers, such as 'snappiness', handle,
feel and look-through.
Han^Sizing.—M hand-made and, in some cases, machine-made papers
are sized in sheets, and the method is called hand-sizing, as it was originally
carried out by dipping sheets of waterleaf into a tub of gelatine.
The sizing is now done by placing the sheets between two endless travelling
felts, which ran through a bath of warm gelatine size. The sheets are carried
into the size and thoroughly soaked in it, the felts, which are very thin, having
holes punched in them to allow the free passage of the gelatine. The excess
size is squeezed off by means of a pair of press rolls, through which the felts
carry the sheets; the latter are then'taken off and stacked ready to be taken to
the drying loft, where they are dried by air at various temperatures. The
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