All of the methods mentioned in this thread require the aquisition of skill. Pour coating ain't as easy as it looks. And blade or well coating can be messy in the hands of someone like me, with the hand-eye coordination of a drunken earthworm. Its realy a matter of personal prefference. I like to pour coat, but cheat by edging the glass plate with a hydrophobic substance,wax.
I will say that, of all the methods I have tried, probably the easiest is the method Denise describes on The Light Farm.
Bill, I'm not sure about how wax would react to the collodion but when doing glass negatives or ambrotypes the edges of the glass are subbed with albumen to keep the collodion from peeling from the glass.
I am still learning to coat glass, but I have never seen Mark Osterman sub his plates nor put "edges" of material on his plates. I have seen him roughen the glass with a file or sand paper before use. He cleans any glass shards off of course. He explained that the rough edges give more edge adhesion.
Friends at Kodak that were involved in making plates said they did none of that, because plates were made in large sheets and cut apart before packing. They told me that chrome alum hardening enforced the adhesion and hardening both. I have seen that work myself. I changed to chrome alum and saw a big improvement in edge and overall adhesion.
I have poured hundreds of collodion plates during the past 2 years, and I've started pouring emulsion for dry plates.
So far, I find wet plate collodion is much easier. It isn't as temperature sensitive as gelatin emulsion. If collodion is a little bit thicker on one side, it doesn't matter because it is a clear substance, whereas emulsion seems to require more uniform application. Bubbles aren't a problem with collodion, and I've had that problem with emulsion poured from a netty pot.
Finally, with wet plate, the collodion is poured off in one direction, but with dry plate, Osterman is suggesting pouring off emulsion on one corner, then pouring off on the opposite corner.
I haven't figured out a good way to catch the excess emulsion when pouring, so I make quite a mess.
I have a puddle pusher, so I'd like to get one of Denise Ross's well kits, if she still has them. That approach does seems like the easiest method.
But I'm going to try pouring one more batch to see if I get better results. I now have a magnetic stirrer so that should help keep an even thickness of emulsion in the pot.
I'm not worried about flaws too much. An island here and there, a speck of dust and some scratches are OK. I want images to appear as though they were struck in the field 120 years ago and defects help achieve that.
i agree bill, pouring plates isn't easy. the biggest ones i poured
were 4x5 and it took a lot of little ones ( 6x6, 6x7, 6x9 ) to get myself ready to do bigger ones .
later i coated windows panes ( standard 6 over 6 sashes and much bigger )
i just used a brush, i was broke and the brush is easy ....
my early "experiments" were well poured but slid down the drain ( i didn't use hardener )
i was just curious as to how george and alfred did it, since it is how "it all started ... "
PE, Yes the edges are roughed with a stone or file. I've actually seen guys just rough the edges with another piece of glass. For ambrotypes this is sufficient but if you are doing a glass negative and redeveloping the negative to build density then the pyro in the developing solution will cause the collodion to shrink and at times lift it from the glass. By subbing I mean that a thin coat of albumen is put down on about 1/8" around the surface edge of the plate. There's nothing worse than getting a nice plate and then watch the collodion slide off during development or intensification. I rough the edges and sub the edges with albumen and have never had one lift. I take one egg white and dip a Q-tip in distilled water and then in the egg white and sub the edges, let it dry for a minute and the plate is ready to pour. That's not much effort to insure the collodion don't lift.
I got some sample plates from the Formulary, and I noticed that they are all polished on the edges. This probably puts a tooth on the edges just as we are describing as the plates are precision ground to exact square and size.
I rub the edges of my plates with a piece of glass, works every time.
PE, That is probably exactly the reason and that is to give the plate tooth. This is not necessary for tintypes, (japanned tin or trophy aluminum) but for glass it is a must. Also for albumen printing or any contact printing process, the albumen subbing on the edges isn't noticeable on the final print. Or let me say if it is I can't see it.
Interestingly enough, it was not done to commercially produced plates. As I said above, the plates were cut from a large sheet of glass after coating and this would preclude any edge treatment that would help.