Just wanted to say a quick thanks to Sandy for the suggestion to use hypo-clear on stonehenge rising. This in addition to the hydrogen peroxide fixed all of my problems. I am starting my calibration procedure over again (the color pallete is clearing right now) and should be up and printing in 1-2 days!

Instead of potassium oxalate to citric to 2x EDTA I printed a sheet of stonehenge with some aluminum foil on it (didn't have any ruby lith handy) and sent it through pot ox, citric, and then hypo-clear. The hypo-clear definitley did its job!

I have also made the observation that in both cyanotype and in palladium Green 255 + Red 0-255 is the grainiest combination with the Epson Durachrome inks. Green 255 + B 0-255 seems to be the best for me.

In my experience, papers that clear very slowly in citric acid often clear very quickly using a solution of disodium EDTA in warm water. Disodium is key.

Just wanted to say a quick thanks to Sandy for the suggestion to use hypo-clear on stonehenge rising. This in addition to the hydrogen peroxide fixed all of my problems. I am starting my calibration procedure over again (the color pallete is clearing right now) and should be up and printing in 1-2 days!

Instead of potassium oxalate to citric to 2x EDTA I printed a sheet of stonehenge with some aluminum foil on it (didn't have any ruby lith handy) and sent it through pot ox, citric, and then hypo-clear. The hypo-clear definitley did its job!

I have also made the observation that in both cyanotype and in palladium Green 255 + Red 0-255 is the grainiest combination with the Epson Durachrome inks. Green 255 + B 0-255 seems to be the best for me.


You may also want to look at some of the comments on the thread regarding contrast control with dichromate. The additon of about 1ml of a 5% solution of potassium dichromate to the developer will give almost idential results to the addition of a couple of drops of peroxide per 2ml of senstizer, and if anything clearing is even easier. In fact, when dichromate is used as the contrast color agent I have found that some papers, including COT320, clear almost completely just by soaking in water.

Sandy

You may also want to look at some of the comments on the thread regarding contrast control with dichromate. The additon of about 1ml of a 5% solution of potassium dichromate to the developer will give almost idential results to the addition of a couple of drops of peroxide per 2ml of senstizer, and if anything clearing is even easier. In fact, when dichromate is used as the contrast color agent I have found that some papers, including COT320, clear almost completely just by soaking in water.

Sandy

You are supposed to tell me these things before I start something else! :)

I have a couple of questions about using potassium dichromate, but I will add those to the other thread. If it helps in the clearing and I don't have to deal with the effectiveness variable of peroxide then I will switch--I have some prints I have to get out first, though.

In my experience, papers that clear very slowly in citric acid often clear very quickly using a solution of disodium EDTA in warm water. Disodium is key.

Unfortunately there has not been much information in the literature about the importance of pH in printing with ferric oxalate based processes, including both kallitype and Pt./Pd. In my own work I have found that print clearing is made vastly easier if the pH of the developer is kept quite acidic, say on the order of pH 6.0 to 6.4. If this condition is met most papers clearly very quickly in mild clearing baths, say no more than ten minutes in 3% citric acid.

Potassium oxalate and sodium citrate developers should be slightly acidic when freshly mixed, but as you run paper through the developer there may be a gradual increase in pH from the papers, most of which tend to be slightly alkaline. You can compensate for this increase in pH by adding to the developer about a spoonful of oxalic acid (for potassium oxalate) or a teaspoonful of citric acid (for sodium citrate). A spoonful per liter will drop the pH on average of about .5 to .8 units.

It is also not a bad idea to check the pH of freshly mixed developers. Most of the sodium citrate in powder form that I have purchased gives a slightly base solution when freshly mixed. This may cause staining in both kallitype and palladium printing. What these processes have in common is that residual ferrous iron, Fe(2+) left over from the reaction process will change to iron hydroxide in an alkaline environment, *during development*, and this can result in staining that no amount of clearing will remove, regardless of the strength of the clearing agent. So if you mix your developer from scratch be sure to add an excess of oxalic acid (potassium oxalate) or citric acid (sodium citrate) to the developer to assure that the developer is acidic. Better to keep the stain from forming in the first place than having to worry about clearing it with a very strong clearing agent.

Sandy

Unfortunately there has not been much information in the literature about the importance of pH in printing with ferric oxalate based processes, including both kallitype and Pt./Pd. In my own work I have found that print clearing is made vastly easier if the pH of the developer is kept decidedly acidic, say on the order of pH 6.0 to 6.4. If this condition is met most papers clearly very quickly in mild clearing baths, say no more than ten minutes in 3% citric acid. .


Sandy
Sandy,

Any recommendations about where to purchase ph indicator strips?

Thanks,

Don Bryant

Sandy,

Any recommendations about where to purchase ph indicator strips?

Thanks,

Don Bryant


Don,

Try these folks. http://www.archivalsuppliers.com/shop/subcategory907.html

Also, American Science and Surplus often carries pH strips. I bought a whole bunch for a couple of dollars just a few months back. Edmund Scientific would surely have them as well.

Sandy