Date: June 04, 2012 07:05PM
I make 8x10 ambrotypes out in the field. I use Coffer's Old Workhorse, a Ferrous/glacial/grain alc developer, and fix with Sodium Thio.
I varnish with Soluvar Glossy Varnish mixed with Paint Thinner (1:1). This has been great to use for ease of mixing, and I have gotten good results generally, until recently.
I do not heat the plate, just pour, blot excess and leave in dish rack to drain/dry in a dust-protected space.
Question: what might be causing the very speckled surface after varnish dries? The speckling does not interfere significantly when viewing the plate, but it does not seem right to have this textured surface and, at odd angles to the plate, it is very distracting.
I suspect the following:
- some kind of dirt embedding onto the surface the collodion at some point when wet (though I cannot see a texture to the collodion when dry, before pouring varnish)
- some reaction of varnish to surface of collodion
- as it tends to be more pronounced in more humid conditions, possibly humidity on plate.