Under "Common problems in the Negative Process and their Cure", Dr. Vogel covers a frightening list of things which can go wrong. Among them is "Kräuseln und Pockenbildung", which is what has happened to you...
Freely translated and excerpted from "Taschenbuch der Praktischen Photographie", XII ed., 37th-42nd thousand, by Dr. E. Vogel, Berlin 1904:
"This happens rarely during develoment, more often in fixing, even more during washing. Causes: A) Plate preparation fault, B) Use of too alkaline developer, C) Use of too concentrated or too old fixer, D) Too hot developing- or fixing bath. Cures: A) One puts the plate, after developing, for some minutes in a bath consisting of 1 l saturated Alum solution, in which one has mixed 300 ml saturated Sodium Sulfite solution and acidified with 15-20 cc Acetic Acid. B) Or one uses the Alum fixer as described on page 153. It is advantageous to cool the developer and fixer bahts. In hot climates one should always work with cooled developer and use the Alum fixer. Advantageous is also the use of the Aceton-Pyro-Developer, with which edge defects (Kräuseln) or blistering (Pocken) rarely occur."
On page 153, the Alum-Fixer:
"Many kinds of plates will get, during fixing, especially in hot weather, blisters, or the emulsion comes loose from the edges of the plate. These plates are fixed in the alum-fixer bath.
This has the following composition:
A: 1000 cc water,
64 g crystalline Sodium Sulfite,
350 g Sodium Thiosulfate
B: 1000 cc water,
80 g Potassium Alum,
28 g Potasium bisulfite
Solutions A and B are quickly mixed as soon as all ingredients are dissolved.
This bath works slower than the ordinary acid fix, but is - espacially during hot weather, much to be recommended.
The Alum-fixer bath is frequently given without the addition of Sodium Sulfite; this has the disadvantage of separating Sulfur, which sticks to the gelatine and must be removed from same with a soft brush before drying."
On the preparation of glass plates for coating:
In Dr. Vogels days, silver bromide - gelatine plates were commercially available. Most of hat he writes about plate preparation deals with colour-sensitizing premade plates, or (as a kind of "Alternative Process?) preparing your own wet collodion plates. Here's a short summary of the process for et collodion:
Plates are acidified by immersing in a mixture of equal parts concentrated Nitric acid and water for some hours. If the plates have been used before, they must be put in saturated soda for 12 hourd before this, and well washed, to remove all traces of laquer. The acidified plates are washed in lots of water while scrubbing with a brush, paying particular attentoin to the edges.
Next step is to polish the plate: The well dried plate is put in a special polishing frame with the side chosen for coating on the top. A few drops of strong ammonia solution re put on the plate, and rubbed well with a clean linen cloth; first from left to rght, then from top to bottom. It is then wiped with a clean cloth (he doesn't say whether this must be linen, too). After this breathe on the plate; if the mist is evenly and uniforly spread, the plate is ready.
Instead of the polishing, it is possible to prime the plate with a coating of chrom-gelatine:
Dissolve 1 g gelatine in 300cc hot water; after cooling add 6 cc filtered 2% Chrom-alum solution. Filter the mix twice. The primer will be usable for four to six days.
The plates are acidified and brushed as before, then covered with a sufficient amount of the primer to cover thinly and evenly, then spill over the edge. Do not reuse the runoff. A second coating is necessary; after this the plates are put vertically to dry and run off.
Pyro-Acetone developer:
A: 200 g Sodium Sulfite (crystalline)
500 ml distilled water,
8 drops concentrated Sulfuric acid
14 g Pyrogallol
B: 1000 ml distilled water
50 g crystallins Sodium Carbonate
Mix 20ml A with 40ml B for use.
This is the Pyro-Soda developer.
For the Acetone-developer, 30ml A is mixed with 60ml water and 10ml acetone.
All translation errors are of my own making. If the wording or constructions seem strange, that is probably a consequence of translating from German to English through Norwegian.
The reason for the small volumes of developer is that this was meant to develop one glass plate - which does not curl or float to the surface of the tray...
I hope this helps - or at least, that it is interesting
Ole Tj
