I am starting up with wet plate photography and I am quite pleased with my progress. I am shooting at the moment on collodion made up with Potassium Bromide and Iodide. The Collodion is made from scratch with guncotton (nitrocellulose).

I am following both Mark Osterman and Will Dunniways manuals.I want to get hold of John Coffers material, but I struggle to send the money over from South Africa.

So, as reference I have these manuals and the internet.

One thing that I am struggling to determine is the the setting point of the collodion. What is the visual guides that will give me an idea of the setting point and how long will it take before I can expect it?

Also, after development, what is the signs of placing your plate to early and to late.

Francois Pretorius
Cape Town, South Africa

I think you are referring to the 'skinning' when you are able to lower it into the silver bath.

the standard rule is that you shouldnt be able to lift off the bottom drip on your pour off corner. that drip must skin over. It can be very quick in hot weather or fairly slow in cold weather *especially if your collodion has a lot of alcohol in it*.

Too soon in the bath, you get streaks and swirls, and uneven sensitization.

too late to get into the bath, the upper parts of your plate, where the collodion is thinnest...this may turn whiteish and not produce an image.

Ray, the collodion I am using is quite thin. How does the skinning of the collodion look like, that is when it ready to go into the silver bath.

If your collodion is thin, practice holding the plate NEARLY level during the period after you drain off the excess collodion back into the pour bottle. Keep it level, and watch the reflection of something, anything, on the surface of the liquid collodion you just poured. Soon, youll see a "skin" develop, this is the outer layer losing some of its solvents and actually skinning a bit. It remains permiable, so some sensitization is into the collodion , the same as a gelatin emulsion, while most of the action is on the surface. Now you are holding the plate with only the drip corner a little bit below level, hold it this way for what may seem too long to you, and touch the drip corner. If it is dryish, and dosent come off wet on your finger the plate is ready to lower into the bath in an even sweeping plunge, without hesitation.

As soon as it touches bottom on the dipper, raise the dipper a few times and tap it on the bottom. I think this helps even sensitization. Leave the plate in four minutes and then take it out dry the back and make a picture.