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Kodak cut or scribed the emulsion surface before cutting the glass. IDK the details.
My references are Wall and also Baker on early emulsions up to the 40s.
Brushing introduced brush strokes, but imbibition of sensitizing dyes introduced other problmes of uniformity as the adsorption was not optimum in salted gelatin coatings. Again, I don't remember details as I never worked in this area.
PE
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muchismas gracias
 Originally Posted by Photo Engineer
Kodak cut or scribed the emulsion surface before cutting the glass. IDK the details.
My references are Wall and also Baker on early emulsions up to the 40s.
Brushing introduced brush strokes, but imbibition of sensitizing dyes introduced other problmes of uniformity as the adsorption was not optimum in salted gelatin coatings. Again, I don't remember details as I never worked in this area.
PE
pe-thanx
vaya con dios
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Originally Posted by Photo Engineer
Ok, here is a repost of the formula copied from the other post here:
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To 90 grams of distilled water, add 5 grams of photo grade gelatin and bring it to 40 deg C. Stir constantly. When dissolved and there are no floaters of gelatin, add 3.51 grams of reagent grade Sodium Chloride (NaCl). (I find dissolving the gelatin first is best)
wait, should this be 90 ml of water, or are you just switching off between ml and grams? (if so, is the next one that the silver nitrate is in in grams or ml?)
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I am so happy to see all this great information pop back up in a thread! I have tried a little bit to do this, but very much want to make my own emulsion for home brew glass plates. Couldn't be happier if I tried. Add big smile here!
thank you!
Robert N.
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Originally Posted by knoxissimpler
wait, should this be 90 ml of water, or are you just switching off between ml and grams? (if so, is the next one that the silver nitrate is in in grams or ml?)
All measures are in grams.
PE
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thank you, but just curious (as I am a newb to the mixing of photo chemicals) is the water in developer, stop and fixer also measured in grams? or is that just a personal preference
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Water and indeed gelatin, silver and almost all chemistry involved in emulsion making is done in weight/weight units due to ease of workup in the dark and viscosity issues. Processing solutions can be done vol/wt or vol/vol units. However, remember that viscous concentrates such as HC110, measured in volume must be carefully measured. You must rinse out the measuring container of the syrup. You can leave a lot behind in a measuring cylinder or cup.
This is why, in emulsion making, where gelatin is so viscous, that we use weight measurements. When you get the right weight, you have it 'all'. Also, reading a graduate cylinder or syringe in the dark, especially with emulsion, is very very difficult.
PE
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sorta in a bind, I made the emulsion (finally got it approved), but tomorrow is the only time for another two weeks that I can use the darkroom... problem is, if the gelatin is solidified, besides using a hot plate, how can I melt it to apply it to the paper/ other material? I thought about using a copper coil with hot water running through it, but will the copper react with the silver chloride (I KNOW it will with any excess silver nitrate, but I do not believe that will be enough to cause major issues)... I do not know what to do, if someone could please post soon...
P.S.: the container I ended up using (since my other one broke) is unfortunately, plastic...
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I weigh out the emulsion I need and it can go into a plastic, glass or Stainless container. Then I put it in a tray of water at 110 deg F and melt it. Then I add finals and coat the emulsion. Finals include hardener and surfactant.
PE
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