4x5 "brush agitation"

I recenly saw a thread that mentioned tray development of one 4x5

sheet at a time with "agitation by brush". I did a search to no

avail and was wondering if anyone using this method could elaborate

on the advantages?? Thanks

Brush agitation probably provides the most even development. Development requires by-products to be removed fromthe emulsion and replaced with fresh developer. Unfortunately, you have a laminar layer atthe emulsion surface - a thin layer of the solution is literally stuck to the surface of the emulsion. Most agitation schemes rely upon diffusion at the laminar surface to excahnge developer and by-products of development. Brush agitation is obviously much more efficient since the bristles literally break up the laminar layer.

 

Brush development was/is used by the astronomy crowd. The downside is that you have to do one sheet at a time and you need good technique. There is also some risk of scratching the emulsion if you use poor quality brushes or poor technique. I think you might find some discussion on the technique at either lfphoto.info or apug.org - some of the folks there do use brush agitation. I think a hake brush is recommended (the Japanese type without metal ferrules). Ideally (and this is possible with smaller negs like 4x5), use a brush wide enough to cover at least the width, so one stroke covers the entire film surface. If not, you will need to work on technique to ensure even brushing. As with all developing techniques, agitation and a steady, consistent action are the goal.

 

Cheers, DJ

Hi Bruce. I think I'm the person you quoted, as I remember the thread. I use a cheap, foam 4" paintbrush, but I would caution you if you use Efke films, as I understand their emulsion is VERY delicate, that you test on a non-critical sheet before committing to the foam brush. With brush development a one-size-larger tray is not necessary, and the smaller tray reduces the movement of the film in the tray, so use a 4x5 or 5x7 tray for 4x5 film, and an 8x10 tray for 8x10 film, etc. I typically expose in low contrast light and extend development, so I agitate continuously, alternating vertically and horizontally, although this is not necessary with 4x5, and probably not with 8x10 either, but I get bored going the same direction the whole time. Good luck.

I like brush agitation because of the great uniformity. You can brush constantly or use intermittent agitation. I attach the film to a Plexiglas plate and develop four 4x5 at a time in an 11x14 tray. There was a very informative article about brush agitation in the July/August 1993 issue of View Camera.