Re: Dry Plates too!!

Hi,

Since we are on the topic of "Dry Plate" as the carry base for the
emulsion, I am thinking in terms of glass dry plate as the carrying
medium. I have a number of 8x10 and 5x7 glass plate holders, and I
measured the thickness of one of the glass plates that shattered in
transit. It is 1.5mm in thickness. Was this a standard thickness for
glass plate?

Were would I be able to acquire glass plate in that thickness? I am
assuming the local hardware store is out since window glass is not
usually the flattest of glass that one can find nor the right thickness.
  Is there someone in N. America that still makes glass plates, for
scientific purposes? I read somewhere that astronomers still use glass
plates for making time exposures over several nights. Where do they get
their plates?

   Any clues and information would be most welcome.

Regards,
Bogdan

Ryuji Suzuki wrote:

> From: Robert Newcomb <newcombr@uga.edu>
> Subject: Re: Dry Plates too!!
> Date: Thu, 22 Jun 2006 08:09:20 -0400
>
>
>>I too am interested in learning to make a gelatin emulsion that can
>>be coated onto glass for in camera use. Since very large sheet film
>>is getting harder to get and way more expensive I am motivated to do
>>something for myself. I have used photo paper in pinhole and lens
>>cameras in the past and can be quite happy with the slow speed and
>>non- panchromatic light response.
>
>
> That's a more realistic first goal.
>
>
>>The store bought emulsions seem to suffer from fog,
>>vary from batch to batch due to age and are expensive.
>
>
> Well, you'll have the same problem with your home-made emulsion.
> In order to make the emulsion keep better, you'll have to have
> additional chemicals (that are not available from your favorite
> photographic suppliers) and refrigeration.
>
> Another problem with paper negative is that paper emulsions have very
> low resolution.
>
> Glass plates also have interesting flaws such as halation, unless
> antihalo coating is made. People in this group would probably rather
> have halo for interesting effect, though.
>
>

-- 
________________________________________________________________
   Bogdan Karasek
   Montréal, Québec            e-mail: bkarasek@videotron.ca
   Canada
                   "I photograph my reality"
__________________________________________________________________