Re: Adhesion

I'd guess the silane doesn't care whether the gum is crosslinked or not and,
it won't have any effect on the crosslinking.
It simply adheres to both glass and gelatin (or gum, hopefully), making a
close bond between the two. In my opinion the quality of getting dissolved
by water has nothing to do with adhesion. That mainly depends on the degree
of crosslinking.
Consider the situation when dealing with a silane subbed glass plate. The
tiny silane layer firmly adheres to glass (actually, it's very difficult to
remove it again). At the same time it provides (what you previously
called )"teeth" for the gelatin (gum)...

Martin

----- Original Message -----
From: "Katharine Thayer" <kthayer@pacifier.com>
To: <alt-photo-process-l@sask.usask.ca>
Sent: Thursday, February 17, 2005 9:16 AM
Subject: Re: Adhesion

> MARTINM wrote:
>
> Katharine Thayer wrote:
> >
> Is silane something that a person can get a small amount of,
> > > and has anyone actually used this to print gum on glass or other hard
> > > surfaces?
> >
> > Yes, I expect "silane" to work in such a case. Note there is a large
> > variety of different kinds of "silanes". Take a look at:
> > http://www.powerchemical.net/index.htm
> > You may pay special attention on "silane coupling agents".
> >
> > "Silane coupling agents belong to a class of organosilane compounds
having
> > at least two reactive groups of different types bonded to the silicon
atom
> > in a molecule. One of the reactive groups of different types (ex.
methoxy,
> > ethoxy and silanolic hydroxy groups) is reactive with various inorganic
> > materials such as glass, metals, silica sand and the like to form a
chemical
> > bond with the surface of the inorganic material while the other of the
> > reactive groups (ex, vinyl, epoxy, methacryl, amino and mercapto groups)
is
> > reactive with various kinds of organic materials or synthetic resins to
form
> > a chemical bond.
> > As a result of possessing these two types of reactive groups, silane
> > coupling agents are capable of providing chemical bonding between an
organic
> > material and an inorganic
> > material."(http://www.micchem.com/products/SilaneCouplingAgents.htm)
> >
> > I am not sure whether the 3-aminopropyltriethoxysilane is the best
silane to
> > use when dealing with gum arabic solutions. 3-aminopropyltriethoxysilane
> > used to be the standard agent to promote gelatin (silver-halide
emulsions)
> > adhesion on glass.
> > Prior to the introduction of silanes, glass subbing had also been done
with
> > sodium/potassium silicate (water glass). By the way, temperature was
said to
> > play a crucial part when coating gelatin on glass. 50°C was considered
about
> > the upper limit.
> >
>
>
> Sorry, I've been laid up for a few days and am still not super great,
> but trying to get back to work. Going out the back door toward the
> studio Monday morning, I slipped on ice and came down hard on my back on
> the steps, bending and cracking a rib in two places. So I'm a little
> behind on the list traffic again. This has not been the best month of my
> life so far.
>
> Thanks for the further information above, Martin. If this isn't the
> right silane, what would be, I wonder. It sounds like some experimenting
> may be required and I just can't be doing any more experimenting between
> now and March 1. So I guess I'll go with my present plan unless someone
> can tell me they've actually used a silane with gum and it's worked.
>
> My first question would be: how would the silane know to adhere the gum
> to the glass only in the exposed areas and not in the unexposed areas?
> Katharine
Received on Mon Feb 21 12:05:53 2005