Photogravure and Ferric Chloride Questions

Hi:

I'm still working on learning photogravure and I'm at that stage where I have to deal with the etching acid. This is gonna be interesting since I don't know anything about chemistry...but that never stopped me before.

I find myself in need of a source of ferric chloride (iron(III) chloride). The text I'm using, "Copper Plate Photogravure: Demystifying The Process" says it is best to buy this in liquid form. After reading the book, I can see why.

The book says to buy '40% by weight by volume ferric chloride', previously known as Rotogravure Iron 48 Degree Baume.

I Googled it and I found this place:

http://www.artchemicals.com/Ferric-Chloride-41-Baume-SolutioncenterCAS-7705-08-0center-P361C28.aspx

I don't know anything about them, but I'll give them a call next week.

I note that theirs is 41 degree Baume, not the 48 degree called for by the text. The text gives procedures on raising\lowering the Baume. It says to start with 48 deg. and add distilled water incrementally until it reaches 45 deg, then repeat until the next container is 43 deg, and so on until you reach 39 deg, which is the strong etching mixture. Apparently, 48 deg is a weak acid and adding distilled water increases it's acidity and etching speed.

The text says I should end up with 5 bottles of this acid: 48 deg, 45 eg, 43 deg, 41 deg, and 39 deg. I will have to adjust up and down the scale from the 41 deg commercial brand.

If I buy this 41 deg, I will have to proceed from a stronger acid and raise it's Baume reading until I get to 48 deg, resulting in a weaker acid. The text says to do this by adding dry ferric chloride to the pre-mixed commercial product and then proceeds to give stern warnings about adding dry ferric chloride to liquid of the same.

In order to avoid adding dry ferric choride to the liquid, does anyone know where I can buy the 48 deg. premixed liquid version?

When I get the liquid version, I have to remove 'free acid' from the solutions. One way to do this is to toss some thin copper strips into the acid to help 'season' it and let the acid eat up som copper and rid itself of the free acid. Is that all I do - just add some strips and leave them? Will they eventually dissolve completely?

I'd appreciate any advice from anyone who has actually done this. I would like to avoid playing chemist. If the warnings are too strong and it's not such a big deal to mix in the dry ferric chloride, please let me know. If you can help me buy the right 48 deg. Baume solution, that would be a big help. Until then, I'll keep Googling.

Thanks.

-R

Actually, an obvious question just popped into my head.

Do I really need more than one solution of ferric chloride other than the 41 deg? I infer from the text that 41 deg may be a little on the strong side as far as etching speed goes, but is that ok? If I can live with one solution, that would simplify things quite a bit. Ideas?

Thanks.

-R

You start with the stronger solution for the shadows and work your way up to the lower baume for the highlights...so yes you do need different solutions. And when you get to the last bites things go real quick. I don't remember what I started with but the stuff I bought from daniel smith did not need dry ferric chloride added. Do you have a hygrometer?

If you've gotten past the part about making a good carbon print on a piece of copper, you're doing good. The real problem is that you have to ink a plate and print it to know how to etch it. There's gonna be a whole bunch of trial and error in your future.

One more question, what kind of ground are you using?

Mateo said:

You start with the stronger solution for the shadows and work your way up to the lower baume for the highlights...so yes you do need different solutions. And when you get to the last bites things go real quick. I don't remember what I started with but the stuff I bought from daniel smith did not need dry ferric chloride added. Do you have a hygrometer?

If you've gotten past the part about making a good carbon print on a piece of copper, you're doing good. The real problem is that you have to ink a plate and print it to know how to etch it. There's gonna be a whole bunch of trial and error in your future.

One more question, what kind of ground are you using?

Click to expand...

Daniel Smith doesn't seem to carry ferric chloride solutions anymore. I looked around some more and found other pre-mixed solutions but they are all 41 deg. So far, it looks like I'll have to start with that and then modify to get other Baumes. What did you buy from Smith?

I don't have a hydrometer or hygrometer yet. They are on the shopping list, though.

I am not using a ground. I haven't actually made a plate yet. I have gotten to the interpositive step and I'm just getting into sensitizing the pigment paper. I have a lot more to do.

Do you have any advice on what ground to use?

Thanks.

-R

Jon Goodman recommends the Fuji-Hunt Blue Label ferric chloride because of its purity. You will need a baume hygrometer to make your various baume strength solutions. Make sure it is one that will read with the precision you need to dilute your ferric chloride.

I think the ferric chloride is actually called a mordant, which I understand creates a slightly more complicated chemical reaction than a straight acid. Maybe some chemists can enlighten us with the semantic difference between the two. Here is a wikipedia arcticle : http://en.wikipedia.org/wiki/Iron(III)_chloride

Anyway, that was a major aside.

As far as the ground goes, there are two basic methods. And you have to use one to them for the process to work.

The traditional dust-grain photogravure uses finely ground rosin, which is heated and melts to form protective grounds. Back in the old days, they used finely ground asphaltum, but it is really nasty stuff, and I don't think many people use that any more. You will need a dusting box of some sort to use this, as well as a good dust mask.

The other method is to buy or make a stochastic screen, which is used to make a second exposure on your tissue which will selectively harden tiny random dots of the gelatin tissue to prevent the ferric chloride from penetrating and etching the copper plate. Both serve the same function, but have slightly different looks. I prefer the dust grain randomness, but it is a lot more messy and laborious to use than a screen.

I would highly recommend learning this from someone who is an expert. There are a lot of steps involved, and the odds of getting a good plate the first time with only a book at your elbow are not very high.

reggie said:

Daniel Smith doesn't seem to carry ferric chloride solutions anymore. I looked around some more and found other pre-mixed solutions but they are all 41 deg. So far, it looks like I'll have to start with that and then modify to get other Baumes. What did you buy from Smith?

I don't have a hydrometer or hygrometer yet. They are on the shopping list, though.

I am not using a ground. I haven't actually made a plate yet. I have gotten to the interpositive step and I'm just getting into sensitizing the pigment paper. I have a lot more to do.

Do you have any advice on what ground to use?

Thanks.

-R

Click to expand...

If you want to use asphaltum or rosin you'll have to make a box and risk damaging your lungs, something I didn't want to do so I went with the Zacryl and an airbrush. I guess it's also possible to use a screen you expose with the plate in a second exposure without the positive.

I just checked and the stuff I got from daniel smith was 45deg baume and I bit the plates at 45, 43, 40 and 38 baume.

here is a picture of a plate I made using the zacryl ground airbrushed on the plate.

(there was a url link here which no longer exists)

Mateo said:

If you want to use asphaltum or rosin you'll have to make a box and risk damaging your lungs, something I didn't want to do so I went with the Zacryl and an airbrush. I guess it's also possible to use a screen you expose with the plate in a second exposure without the positive.

I just checked and the stuff I got from daniel smith was 45deg baume and I bit the plates at 45, 43, 40 and 38 baume.

Click to expand...

Thank you, Mateo, for pointing out this company to me. I checked out their web-site and it's like they made it just for me! I had seen some liquid aquatint at Daniel Smith (I live about 3 blocks from them!). I was pretty surprised - the liquid is mentioned in the text I'm using but they don't seem to discuss it's pros\cons. It certainly seems more convenient, but I don't know difference it will make in the etch.

I will defenitely try the liquid aquatint in my first plates. Do you think I need the airbrush at the beginning, or can I just pour it on?

Do you recommend any of their other products, like the copper plates, the ferric chloride (only $14\gal), the vertical tanks, etc?

If you have any other links to suppliers\equipment I would appreciate it if you would share them.

Thanks again.

-R

I'm really gonna recommend a printmaking class or workshop. You almost need to be a printmaker playing with photography to do this. The ground has to be airbrushed on because you want it to make a texture on the plate. The whole point of the ground is that it gives you a bunch of little dots that ain't effected when you bite the plate. What you're doing when you make a plate is making a range of different depths of texture. When you ink the plate and wipe it, the ink stays in the holes and gets cleaned off the smooth areas. If you look at the plate I put in the gallery you'll see there's a border around the image; that border gets inked along with the rest of the plate but after wiping it prints paper white because it ain't got nothing to hold the ink.

Mateo said:

I'm really gonna recommend a printmaking class or workshop. You almost need to be a printmaker playing with photography to do this. The ground has to be airbrushed on because you want it to make a texture on the plate. The whole point of the ground is that it gives you a bunch of little dots that ain't effected when you bite the plate. What you're doing when you make a plate is making a range of different depths of texture. When you ink the plate and wipe it, the ink stays in the holes and gets cleaned off the smooth areas. If you look at the plate I put in the gallery you'll see there's a border around the image; that border gets inked along with the rest of the plate but after wiping it prints paper white because it ain't got nothing to hold the ink.

Click to expand...

I fully agree about the workshop. I plan on taking one next year. Anderson Ranch and maybe Jon Goodman. I am looking for other possible sites. Until then, I am going to get my hands dirty making plates and using the press. I have a master printer here to help me with the press and printing the plates. She doesn't want to make plates, so I'm working thru that myself. I know it's not simple, but I am reasonably sure I can get some plates etched, and if there is nothing to lose except money, why not go for it? I am used to learning and working with complicated proceses at work so I'm not daunted by this process. I just find that it's important to understand the 'why' of each step and not to do anything unless I'm clear on that.

I'm pretty clear on the process up thru deveoping the gelatin tissue and I'm just starting to get the picture on the etching process, thus the questions. Just mark my ignorance up to riding the learning curve. I'll get it worked out.
Thanks for your help so far.

-R

So...I actually *am* taking some printmaking credits right now for my MFA, with the intent of doin some photogravures. I am strongly considering having a plate made for me, so that I can get back into the 'printmaking' side of it (having been out of it for nearly 15 years...), then attempt to make my own plates.

Is it 'cheating' for me to have a plate made to get back up to speed in the printmaking studio? I have an old plate, my first photogravure, to play with, but I want to experiment with some new imagery.

My instructor doesn't have a problem with this approach...just wondering what APPUG'ers think?

Thanks.

No problem as far as I'm concerned. I don't see an ethical problem if you just intend to use the place to re-learn the process.

I was thinking of doing the same thing myself. The thing that is holding me up from just going out and printing is that I don't have a plate. I wish I knew someone, somplace to get one so I can work on the printing sooner. It is taking a heck of a long time to get the platemaking going. But, when I thought about I was worried that the one plates that I'd get were someone's rejects.

-R

Plates for photogravure

Mateo said:

If you want to use asphaltum or rosin you'll have to make a box and risk damaging your lungs, something I didn't want to do so I went with the Zacryl and an airbrush.

Click to expand...

Mateo,

I have recently been participating in a 'printing' course where we have used black enamel spray paint to obtaining an 'aquatint' effect with finer 'grain' for intaglio printing.... the spray is directed 'over' the plate while being allowed to 'settle' as per using rosin. Might this method be substituted for rosin to reduce the health risk for making photogravure plates?

Ken

About the ferric chloride: you can let the water evaporate from it to increase the baume. Keep in mind that the baume is relative to the temperature of the liquid, so pick a consistent temperature to measure (and work) at.

About "free acid." Dropping a piece of copper into the etch "seasons" the etch, and does not remove the free acid. To neutralize ferric chloride:
1. add two ounces of liquid non-detergent ammonia to eight ounces distilled water.
2. add two ounces of stock ferric chloride solution (ie, 48 baume) to eight ounces distilled water
3. mix solutions 1&2. let the mixture stand for 30mins, a sludge (ferric hydroxide) will form at the bottom. Decant the liquid and add the ferric hydroxide sludge to one gallon of stock ferric chloride. This will neutralize the etch.
4. allow neutralized ferric chloride to sit 24 hours, filter out any precipitates.

(from "Photogravure: A Process Handbook," Gary P. Kolb, Southern Illinois University Press -- highly recommended reading)



I'd like to mention that photogravure is probably not the best way to introduce yourself to intaglio printmaking.