One question from outside USA in the same subject: glases (square and
rectangular) with a thin scratch (generaly paralel lines) on one surface
only, no emulsion, no pictures; we are digging in the house of an old
photographer (around 1880). We have from the garbage pit around 500
fragments of that kind. Any explantion?
Daniel


----- Original Message ----- 
From: "Keith and Jennifer Brown" <[log in to unmask]>
To: <[log in to unmask]>
Sent: Thursday, August 10, 2006 4:58 PM
Subject: Re: Early photography question


> According to my photographer husband:
>
> "Those were basically negatives. They painted liquid emulsion on the
> glass, and then exposed it as you would a negative. Something similar
> was done with 'scratching' emulsion off to make a negative drawing that
> could be put in an enlarger to make prints. The black powder referred to
> is the emulsion that has dried up and is coming off since it sounds like
> these things haven't been taken care of."
>
> Hope this makes sense.
>
> J. Brown
>
>
>
> On 8/10/06 11:04 AM, "T. Arron Kotlensky" <[log in to unmask]> wrote:
>
> > Hello all.  A friend of a colleague of mine is looking for information
> > regarding what might be early photographic materials.  She wrote:
> >
> > "A friend has some old glass
> > plates with a black powdery material on the back,
> > with sketches of some of the old Ishpeming
> > mines. I assume they were for making photographs,
> > but am not sure. He'd like to get a little
> > history on them."
> >
> > Any thoughts?  Many thanks for your input.
> >
> > -T. Arron Kotlensky
> >
>