Help with flaking silver gelatin dry plates

[Isaacm9]

First post here! I have been coating and shooting dry plates using Liquid Light emulsion for a while now, but this newest batch, all from one bottle, is doing something strange. The emulsion comes off in flakes all across the plate. They all exhibit this to varying degrees, despite appearing completely normal before processing. I'm thinking I likely messed up somewhere along the way, but I'm wondering if someone has had a similar experience. Using a traditional chrome alum hardened gelatin subbing and Rockland Liquid Light heated to around 140 during coating. Plates cleaned with calcium carbonate.

I've taken all these steps with different batches and had no issues with flaking. The only common denominator is the bottle of emulsion and the subbing batch. Let me know if you have any ideas on what this could be, and thanks! Included images are one detail from a scan and a picture of the negative/

 

[koraks]

Welcome to Photrio! I have no experience in particular with gelatin dry plates, but in carbon printing I've done work with gelatin and some of it has involved glass. So taking that as a basis...

This looks like pinholes due to small bubbles. Have you tried offgassing the Liquid Light emulsion? Maybe it has some air in it. Take some emulsion, melt it, then keep it liquid for an hour or so in a beaker, allowing any bubbles to dissipate.

Plates cleaned with calcium carbonate.

Sounds OK to me; just checking - do you remove all the traces of the calcium carbonate from the plates before proceeding? I find that if I clean glass with carbonate, a very thin film of carbonate tends to stick persistently to the glass unless I gently wipe it off with my hand under the running tap.

 

[ProfessorC1983]

I find the same as the above, and typically add a drop of liquid soap to the cleaning solution, followed by a soft wipe with a clean sponge under running water, and then a final dip of the plate into a mix of distilled water and ethanol before the drying rack. That seems to cut down on "trouble spots" considerably. I don't use a subbing layer and I coat at 40-42C for a 10% gelatin emulsion.

Air bubbles, on the other hand, are a much trickier issue for me!