----- Original Message -----
From: "Laurie Solomon" <laurie@...>
To: <epson-inkjet@...>
Sent: Thursday, June 14, 2001 4:21 AM
Subject: RE: Separating Prints from Glass


> different type of resin coating that enables the creation of surface
> textures on it as well as protecting the emulsion layers from scratching
and
> abrasion. The earlier papers may have been handled differently with the
> coatings encapsulating the only the paper substrata and not the emulsions
or
> on the top and bottom with no middle layer of resin coating.

Resin covers a wide group of materials. Modern coating techniques
consist often of multiple layers. The first could be to increase the
adherence of the emulsion to the corona treated polyethylene,
the second the actual silver containing layer (black and white only
but there seem to be multi sensitive layers in BW too) and then
a less hydrophile gelatine or PVA layer on top.

> With respect to inkjet papers, I would think that there may be a absorbent
> layer between the substrata and a topmost layer which is also a type of
> micropoureous layer, which serves to permit surface textures while
allowing
> the ink to be absorbed by the layer below and protected from being
attacked.

I always thought the microporeus layers are just the absorbent materials
where the particle structure has an enormous surface on a low volume.
Charcoal like. The recipes I have for that kind of material (Laponite)
says mixing it with resolved PVA. In inkjet papers the coatings
are also multiple layered. For instance a barrier layer on the paper,
a gelatine or PVA with a lower amount of absorber on that and a layer
with a lot of absorber on top. I think it is damned difficult to use
membranes on the top without getting puddling and drying problems.

What is interesting (and I have written about it several times) is a
receptive coating that can be closed and sealed after printing so
oxidation of dyes, staining, scratching has less chance. FIRST foils
are based on a heat treatment that lets the absorber particles with
pigment ink sink in the underlying wax/resin layer. Ilford is busy to
develop coatings for dyes and pigments that have similar properties.
End of the year on the market seems to be the goal. Suggested heat
tool is a lamination press but it should work with a hot air gun too.
Whether this works along the lines of the FIRST foil coating or uses
heat sensitive hardeners for the gelatine I don't know. An indication
that it works like the first :-) is the possible use of texture mould foils
in the process so you can create a variety of textures on one kind of
paper.

Ernst


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