Use of FOMA emulsion (Normal) - dryplates

[Simon Howers]

Just a quick note on this material.
I applied emulsion melted at 40 deg C onto previously subbed plates.
Subbing solution was fresh gelatine/chrome alum.
2 x glass plates were cleaned with rottenstone and detergent, dried and subbed.
Metal plate was painted with acrylic black and swabbed with iso propyl alcohol.
Emulsion coating really only works if plate is pre-warmed to assist pouring & drainage.
(See the tin plate below for an example of a cool plate)
Plates left to harden for two days.

Exposure at ISO 10 (half second at F11 in overcast conditions.)

Processing:
All - developed by inspection in trays.

Tin plate developed in Rockland reversal developer for 2 mins then cleared in Kodak hardening fixer.

Glass plates - one developed in Rockland reversal developer for 2 mins to produce ambrotype and cleared in Kodak hardening fixer.

Second glass plate developed in XTOL for about 2 mins, stopped in Ilfostop and cleared in Kodak hardening fixer.

Results: This emulsion handles easily and can be applied economically. ISO 10 is rather better than some others I have tried. It produces nice detailed and clean negatives in XTOL.



Hopefully the thumbnails appear as 'negative', 'ambrotype', 'tintype'

(you can see on the tintype where I failed to pour all the excess off the plate and the emulsion has crazed.)

These were all 5x4 for testing. Wholeplate negs are lovely.

Simon

 

[DannL.]

Thanks for posting these Simon. I especially like how a positive from the negative would look.I made and inversion locally on the pc. What color was the backing behind the negative when it was exposed? I ask because the blooming that occurred in the sky is nice. I've seen this when a light color packing was present. All you need now is to place someone in a suit and top-hat in the picture.

If you're getting ISO 10, that's interesting. Rockland's Liquid Light gives me ISO 1. But, that gives me plenty of time to figure out what I'm trying to accomplish.

 

[removed account4]

great post !
and great samples of your coatings.
lighting conditions also play a factor in
liquid emulsion .. different times of year, and day
there are different amounts of blue light ... iso 10 sure is speedy!

 

[Simon Howers]

A quick update on progress.

I have been coating WP 2mm glass plates with both FOMA and Rollei RBM2 emulsion.
In terms of handling, the FOMA is easier to use for two reasons:
1) It is a little more viscous when melted and is therefore easier to run around the plate without spilling
2) Provided the plate is adequately clean, no subbing is required.
I add 5ml iso-propyl alcohol and a few drops of Fotoflo to each 40ml emulsion as finals.
The plates take at least 36 hours to dry in a ventilated dark box.

I have found that the FOMA reciprocity table works well for both emulsions. This is pretty steep.
So hazy sun approximates to 19secs at f22 on my camera, which is about 1910 with a brass barrel lens.
I should imagine modern lenses would collect light more efficiently.
ISO is interesting! In really bright sun I can confidently expose at ISO 10.
In overcast or dull conditions I find ISO 2.5 is about right. I guess John's point about blue light levels is effective here.

Processing:
Xtol works well enough but tends to render rather 'thin' negatives.

In a search for a denser black, I have been trying a 'charcoal black' print developer.
Currently this is Dassonville D1, formula as follows:
Metol 3.0gm
Sodium sulphite 43.0gm
Hydroquinone 11.0gm
Sodium carbonate (anh) 30gm
Potassium bromide 2.0gm
Water to make to 1 litre.

The recommended dilution is 1+1 but this develops the plates past image to entirely black in a few seconds, probably because of the small quantity of restrainer.

Currently I am working at 1+7 dilution and adding 30ml of 0.2% benzotriazole solution to 800ml working developer.
This makes it controllable. So far I find (minutes)
1:00 - underdeveloped and thin
2:00 - about right
2:30 - too dense - wont print out

I use Ilfostop and Kodak hardening fixer.
The emulsion dries to a nice uniform hard surface which takes normal handling without problems.

I use salt printing.
A plate developed for 2min prints out in about 25mins.
A plate developed for 2:30 produces a faint print after 40 minutes.

The developer certainly provides adequate density, which is a step forward. I have a couple of test prints drying
so I hope to post some comparison examples later.

Simon