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wildbillbugman
10-14-2009, 05:56 PM
jnanian,
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

RobertP
10-15-2009, 02:20 AM
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.

Photo Engineer
10-15-2009, 09:28 AM
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.

PE

Bruce Schultz
10-15-2009, 01:14 PM
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.

jnanian
10-15-2009, 02:01 PM
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 ... "

RobertP
10-15-2009, 02:24 PM
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.

Photo Engineer
10-15-2009, 02:46 PM
Robert;

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.

PE

Anton Lukoszevieze
10-15-2009, 02:48 PM
I rub the edges of my plates with a piece of glass, works every time.

RobertP
10-18-2009, 09:42 AM
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.

Photo Engineer
10-18-2009, 09:44 AM
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.

PE

RobertP
10-18-2009, 10:06 AM
PE, In some of the old literature it talks about using albumen to sub the entire plate. The formula for using albumen to sub the entire plate is: Two large egg whites to 1 liter of distilled water. This is poured on and flowed just like you would the collodion. It then could be cut to any size desired. We also could be comparing apples to oranges here. I'm talking about wet plate collodion and not dry plates. But you could flow albumen on a large plate and let it sit for days or longer before cutting to size and using it to flow your wet plates. I guess that would hold true for coating a dry plate emulsion also. Albumen plates should be used within a few days or stored properly because in hi humidity yeast in the air can react with the albumen and cause contamination spots.

RobertP
10-18-2009, 10:31 AM
Also let me add before you do anything with the glass plates you must make sure they are extremely clean. I use to use "Glass Wax" but it is no longer available. Now I use a "Whiting" mixture which is nothing more than 40 grams of calcium carbonate mixed into 50 ml of distilled water and 10ml of 190 proof grain alcohol. Works great.

Photo Engineer
10-18-2009, 10:39 AM
I am talking only about dry plates. They were not subbed AFAIK nor were the edges prepared in any way. The large 30x40 sheets were coated, dried and then cut into 4x5, 8x10 and etc. There were other large plate sizes besides 30x40.

A special machine was manufactured that cut the coated dry plates, and also removed the glass dust. All of that technology has been essentially lost.

I clean my plates with Potassium Dichromate-Sulfuric Acid grease removal solution after a good wash in detergent. I rinse in DW and let air dry before coating.

PE

Kirk Keyes
10-18-2009, 11:53 AM
Potassium Dichromate-Sulfuric Acid

It's an excellent glass cleaner and I remember the days that it rule them all in chemistry labs.

Now, it's considered environmentally hazardous and not used in most lab applications.

Kirk Keyes
10-18-2009, 11:55 AM
I am talking only about dry plates.

Do you know if the machines cut the gelatin as it scored the plates? It seems like you would have to do the scoring from the emulsion side to get it to work.

wildbillbugman
10-18-2009, 12:56 PM
It's an excellent glass cleaner and I remember the days that it rule them all in chemistry labs.

Now, it's considered environmentally hazardous and not used in most lab applications.

I have read that some people soak their glass plate in a fairly concentrated solution of NaOH. This puts a micro-tooth on the glass and creates a mono-molecular layer of sodium silicate. The later can benefit adhesion.
Bill

Photo Engineer
10-18-2009, 01:56 PM
I use so little Dichromate that it is not a problem. It can be reused over and over for this application. The Sodium Hydroxide should work, but IDK how fast it will react with various types of glass. It can make some glass translucent.

PE

wildbillbugman
10-18-2009, 03:36 PM
Hi,
I would think that soaking the glass plates in NaOH would also serve to smooth out the edges without having to file the edges or sub the edges.
Bill

totalamateur
10-19-2009, 10:19 AM
When I pour my plates, I wash them with Ajax or Comet and scrub the heck out of the edges with a 3m green scrubby. The emulsion I did this with was always a knox-gelatin emulsion (but never again), and I never had any problems with adhesion, no hardener used. Stupid Knox Gelatin will melt right off the plate, though.

To get an even coat, I put all my plates in the oven and heated them to about 120, just hot enough to where they are almost uncomfortable to hold, then keep them in a stack as I pour, so that the plates behind the ones I'm coating smooth out the temperature across the top plates and keep my fingers from causing thick spots. Unfortunately, the last one generally comes out uneven. If I were smart I'd have one extra glass plate that I didn't coat.

I think for big plates, you could make a plywood jig to hold them with a tripod mount on the bottom, so you wouldn't have to hold the weight as you tilt it around, just swivel your tripod head. Several layers of warm glass under the top plate should keep it warm enough until the emulsion is completely coated. The only issue then would be to perfectly level the plate once it's been coated. this was the issue that i had, apparently there isn't a level surface anywhere in my house. Maybe a couple of spirit levels glued to the side of the jig would help.

I'm no expert, just m 2 cents.

Kirk Keyes
10-19-2009, 12:02 PM
Unfortunately, the last one generally comes out uneven. If I were smart I'd have one extra glass plate that I didn't coat.

Get some ceramic floor tiles (they come 12x12 inches) and put them under your stack of glass plates. The ceramic tile should hold the heat for a while and help keep you glass plates warm longer.