Can't get deep black

[A Joe]

I'm using kevin klein's bromide emulsion (TLF) but I can't get deep blacks out of it. It's not exposure (tried a sample completely fogged), it's not developer (both my own D19 and kodak dektol with the same results) and it's not thickness, I coat with brush or puddle pusher and got good blacks with other emulsions.
Dilution is ok, gelatin content is ok (I made this formula more than 10 times), sensitivity is between 1-3 depending on the batch. No fog.

should I add iodide?
thoughts?

P.S.: I meant to post this into the emulsion makers group but I can't.

 

[Sirius Glass]

Welcome to APUG

Fresh developer and/or fresh paper usually will do it for me.

 

[pdeeh]

P.S.: I meant to post this into the emulsion makers group but I can't.

You need to "join" a group (under the "group tools" menu item) before you can post into a group.

But you should get sufficient attention here, don't worry.


Don't worry about comments like "use fresh developer" - the writer probably hasn't noticed you're making your own emulsion and coating it yourself

 

[A Joe]

hehe

 

[ozwoodnbrass]

Hi A Joe ,I have the same problem . I use the same formula or similar to coat my glass plates and I cannot achieve a intensity that I can get with other emulsion .I use Foma and get good results. I understand that a commericially made emulsion will allways be better . Coating thickness does not make a difference . Are you going to try the ammonia ? I am on my next batch.

 

[Photo Engineer]

If you get low Dmax, there are 4 possible causes.

1. Underdevelopment. You can check this out by looking at the BACK of your coating. It should show an image as well, but not as defined as the front.

2. Emulsion too dilute. You overwashed and / or let the temperature get a bit high. The emulsion swelled and became more dilute.

3. Under sensitization with Sulfur or Sulfur + Gold. This leaves you with "dead" grains that produce no image.

4. Too little coating. You should use about 300 mg of Silver (calculated as the metal) per square foot of coating.

To solve 2 or 4, add more gelatin to thicken things up a bit.

PE

 

[dwross]

Hi A Joe ,I have the same problem . I use the same formula or similar to coat my glass plates and I cannot achieve a intensity that I can get with other emulsion .I use Foma and get good results. I understand that a commericially made emulsion will allways be better . Coating thickness does not make a difference . Are you going to try the ammonia ? I am on my next batch.

Not sure where you get the idea the a commercially made emulsion will always be better . (What did we do before emoticons?!) Ammonia will not do much of anything for density. A plain silver emulsion has denser blacks (all things being equal for handmade emulsion). Done right, an ammoniacal emulsion will be faster, however. Dense blacks and speed are often opposing goals.

I invite you to try this recipe. http://www.thelightfarm.com/cgi-bin/htmltutgen.py?content=08Mar2013 . Many people have reported back to me very favorable results.
There are expanded "making" instructions on the pages preceding the recipe.
If you replace the potassium bromide with 4.1g ammonium bromide you get an even better recipe (personal opinion, of course).

As PE noted above, emulsion dilution is an important factor. Watch the steps that influence the water ratio carefully.

I hope you find this useful information.
d

 

[kevin klein]

Sorry to hear your emulsion is not giving you a good density. As far as adding iodide, I tried that a few times and got very thin negatives, that is why I went with the bromide only emulsion. Too thin a coating with this emulsion will make thin negatives.

 

[Photo Engineer]

Well, Iodide up to 3%, added to the emulsion 15 minutes before coating might help, but it might also cause fog.

Give it a try.

PE