Hi All,
I used Citric Acid and Ferric ammonium Citrate (Brown) in the ratio mentioned here. I couldn't use Distilled water though.. Used RO water.
Attached herewith are the images for your reference:
- A. Without Citric Acid - I tried this before I posted here - this should help you see how my images used to be without Citric Acid
- B. With Citric Acid - This was wet Cyanotype as I didn't have the patience to wait for it to dry. This was left in the sun for about 7 to 8 hours.
- C. With Citric Acid - Dried Up Over night and then exposed. The droplets you see are citric acid crystals that I dropped when the emulsion was still wet on the paper - just to see how it turns out. This was exposed in sun for 5 hours on Day 1 and then I kept it inside overnight and exposed again this morning for another 3 hours. I was expecting this to be darker blue as I had exposed for a long time but it did not. Not sure why.
- D. With Citric Acid - This was again dried overnight and then exposed in sun for 5 hours on Day 1 and then kept inside overnight and exposed for 3 hrs today.
- B,C and D - were washed in distilled Water with Little vinegar added in.
- for C and D - I also used some Hydrogen Peroxide to help in oxidation.
Out of all the 4 i feel image B is what is close to the blue I would prefer. Not sure why C and D have got washed out. I thought the emulsion left to dry overnight would be darker!
But I am at least happy that adding citric acid is helping me. Now its just about experimenting the ratio, exposure time, paper etc to see what works best for me.
Here are some questions I have:
- If anyone can help me with how to get better blues it will greatly help.
- I also need help in understanding how to get the details on veins on leaves.. I had left a pupil leaf for almost 20 hours hoping I will be able to get the veins.. But I was not succesful. whatever little details I saw before washing got faded off after wash
- If you notice in B, the whites are not really whites.. there is a tinge of the yellow from emulsion. even though I washed it pretty well. how do I avoid that?
- In image C, the areas where I have dropped the citric acid crystals have come out bright blue. Does that mean adding more citric acid to the emulsion will help me get a bright blue after wash??
Thanks in advance!
Niths
Really good progress here....looks like the citric acid diagnosis was the correct one. You can probably tweak the amount a little bit. Brown FAC can have a range of Fe content so optimum amount of citric acid addition will vary too depending on your particular batch. Seeing the blue spots in C does indicate there is room for higher acid. Nice effect, by the way, it adds some texture to the print. People who do wet cyanotypes add all kinds of stuff to create different textures and colors - this looks like another such technique in the repertoire.
The exposure times on pre-dried prints C and D seem to be awfully long to me - in full sun, it should be exposed in a matter of minutes not hours, particularly where you are. Wet cyanotypes tend to require longer exposures but not dry ones. There is no need to dry it that long either. You can allow air drying for a few minutes until the gloss of the liquid is gone and print looks matte. Then do a quick hair drier treatment before exposing. No need for overnight drying.
Also, how come you are using distilled water for washing but not have any for the sensitizer? (It could be a typo.) For washing, tap water should be fine as long as you are adding an acid to it. That too is most important in the first wash, subsequent ones can be plain water.
Regarding your particular questions:
1. This is a complicated question and it is connected to everything else. I would say revisit it once some of the other issues are figured out and you get a better baseline process.
2. Details in the leaves depends on the type of leaves - some are more UV transparent than others, new leaves for example are better in this regard. So using the right kind of leaves helps - need a lot of experimentation. Having said that, use of acidic wash will promote retention of blue in the highlights, reducing the contrast and expanding the tonal range. You are already using vinegar - try varying the amount (keep track of how much you are using.) Starting at zero, you might see total washout. As you increase the percentage, there will be more and more, until it plateaus at some point.
3. Yellow stains are manifestation of sensitizer (iron) not being completely washed out of the paper. This could be un-reacted FAC and K ferri by themselves or ferric hydroxide formed as a result of reaction between FAC and the chalk buffer (CaCO
3) that is most likely used in the paper. The former is easier to wash out, but the latter is much harder, if formed. Citric acid is a good chelating agent for iron - it works better than the acetic acid to carry these iron compounds out of the paper. Try treating the paper with 1% citric acid and see if it clears. If there is any hydroxide, it is much more difficult to clear once dry so it is best to do this while you are doing the wet processing. You can simply replace the vinegar with citric acid in the process. I would start with 0.25% and see how that works and increase if necessary.
4. It would seem that more citric acid in the sensitizer will give more blue based on the sprinkles. But there is a limit. As you can see even under the leaves there is blue - albeit less intense than the ones outside. So if you use too much then you will not get any whites. It will also promote a tendency for dark-reaction creating "fog" or blue stains even where there is no exposure. So again, experimentation will be required to add the right amount.
Good luck!
:Niranjan.
