[titisteph]

Thanks for reply, Photolytic.
This is very technical, and very interesting… Such a knowledge, I’m impressed. This is great.

At the beginning of my tests with bromine, I did my bromine coating at light. But I stopped, because of a contrast’s problem on the plates. I was afraid it was due to action of light… I realized my mistake later : the problem cames from too much bromine wich created haze on the plates.

From this time, I sensitive my plates in darkness after bromine. And you’re right : I noticed a lower speed than Pobboravsky Exposure Guide. Almost 1 stop is always missing.

Another mistake from me… So, I’ll do my bromine sensitive at light for next plates.

But you wrote my time is too long for second iodine. It should be half as long as the first iodine.
I’m surprised, because my first iodine time is comprised between 2 and 5 minutes to reach strong yellow for the first cycle (between 20 and 26°C). So, 20 seconds doesn’t seem to be too long.

You wrote : Part of the second iodine should be done under white light so you can see the final color of the coating Why is it so important to see the color of the plate at this last point?

[titisteph]

Another question : why is it necessary to put a second time the plate into iodine after bromine?
What happens if the plate is done without 2nd iodine?

[titisteph]

Hello Photolytic,

Thank you for reading my blog! I thought I was the only one to read it! I’m happy to discuss with the man who made that incredible study about hypersensityzing plates. It was very high grade level, and unfortunately, my english level wasn’t not good enough to understand everything. But I loved it.

I have the same name than the famous explorer but it’s a chance. My family doesn’t come from Portugal, but from Brazil (same language).
The first to live in France, it was in 1910. He created the french part of my family from that point. There is no more link with the brazilian part since at least 80 years.

About our topic, I did a test just a few minutes ago, in order to see myself what’s going on.

I put half of a plate for 20 seconds into 2nd iodine. And the other half for 45 seconds.
And the result is surprising : none difference. It’s even difficult to see what is the 20s’s part from the other one.

I’m happy to discover this, because it’s a problem I can forget! So, I continue with 20 seconds.

And, again, thank you so much to give your time to help me!

[titisteph]

Thank your for your interesting documents!

Ok, I understand… So, I made a translation’s mistake!
I understood that I should use aluminum powder. I was wrong.
So, I mustn’t use it!

The problem seem to come from the way the plate was silvered. Maybe the supplier use alimina powder, I don’t know.

When I send my copper plates to the supplier, they are already polished by myself. And I don’t use alumina. I use chrome oxyde stick with the rotary buffer.

I don’t know if the supplier add more buffing after me, and if he use alumina before silvering.

If it’s true, I’m sad, because I have 12 plates made by this way…

[titisteph]

Thank you all for your help.
I’m going to answer to all your questions..

I’m sure my spots are not mercury mist from overdeveloping. Spots from overdevelopping are different, and appears only on black areas on plates, not all over.
But I have never tested Becquerel processing.

My mercury pot is extremely stable, it never moves at all during all the processing. And I filter perfectly the mercury before using (very nice surface of the metal, like a mirror). I clean the mercury box before using it.

From the beginning, I have those black or white spots on all my plates, more or less.

Here is a perfect example from another plate. It’s a giant one!

I’m waiting for the aluminium silicate powder. As soon as I receive it, I’ll do a test. Maybe the problem comes from the silver surface.

Attachments:

You must be logged in to view attached files.

[titisteph]

Thank you Photolytic!

I don’t know how do you manage to use rotary buffer without doing scratches on the plates. With mine, I always have scratches. The polish is good, but with very small scratches, even with very light pressure. I don’t know where I fail.
So, I prefer using random sander with ultrasuede.

My plates don’t have white haze, fortunately, and they have perfect mirror-like aspect, before buffing. I don’t think the plater who is supplying me use any buffing at all, there is none mark on the plates, except for some little scratches because I think he use a cloth for cleaning them.

So, I think my plater seem to be not bad, and this is a good news. It would we very difficult to find another one here in France.

[titisteph]

Hello Photolytic,
Thanks for your answer.
I have the same equipment : high speed rotary buffing machine. But I prefer not using it everytime for polishing silver, because it creates small scratches all over the plate. I only use it for copper, and to remove the image of a gilded plate (because the image is very strong and impossible to remove completely with only random orbital sender)

My question is : where do come from those white and black spots? Is it due to some dust included into the silver layer, wich react with iodine?

And is it absolutely necessary to use nitric acid to clean the plate? Because I would be happy not to introduce ANOTHER dangerous liquid into my lab! But if it’s necessary, I’ll do it. But I need to be sure of the efficiency.

Attachments:

You must be logged in to view attached files.

[titisteph]

Thanks for your help!
No, you’re right, I don’t use rottenstone before rouge… I use to use polish paste wich works very well to remove scratches. I believed it was good enough with only that. I was wrong, I suppose…
So, your advice is to use aluminum silicate, it’s a good idea. I read some topics about that, but I didn’t know it was necessary to use this before rouge.
My plates seem to be perfect after polishing but it seem to be a mistake.

And I don’t use nitric acid… another mistake.

I will follow your good advices and will show you the result!

Thanks!

[titisteph]

Hello,

My name is Tristan da Cunha, I’m from France, and I practice dags since 2013. I’m a professionnal photographer, and I plan to use dag for my work, but I need some more practice. I hope to reach my target soon!
You can follow my progress on my website : http://www.tdacunha.com

I use the complete process, including bromine and mercury. I never use Becquerel way.

[Author]

Posts