carbon transfer

Some standard formulas for carbon printing

Some viewers of my carbon printing videos have asked me to write out some of the formulas for the carbon printing materials and processes I demo in my videos. Well, here you go.

These formulas will get you started. However, keep in mind that they can, and should, be changed as you develop aesthetic preferences and want to change your materials to match. For example, different pigments have varying tinting strength and will require different concentrations. A less concentrated gelatin sizing for art paper will provide a less glossy finish. To retain more or less moisture in the tissue, or change the pliability, the sugar can be varied. So, take these formulas as starting points and adjust as you learn.

Note: In the formulas, the percentages of ingredients are intended for calculating the weight of the ingredient as a percentage of the total volume of the solution. For example, a 10% gelatin solution would require 100 grams per liter and 1.2 percent pigment would be 12 grams. Distilled water is recommended, particularly if your water is alkaline. If you are going to spend hours upon hours making prints from your tissue, it's worth using water you know will be good. It also dissolves ingredients better. 

Glop for making tissue

India ink is a good pigment to start with. It is perfectly dispersed, easy to mix, and does not require you to do any extra straining or filtering of the glop after mixing. It produces prints with deep blacks, warm undertones, and a glossy finish. I use Speedball because it is easier for me to buy. It can be bought off the shelf at many art supply stores. Black Cat can be ordered from Dick Blick. Speedball is more concentrated and seems a bit more glossy in finish. The pigment percentages below are simply ones I have used in the past based on their relative concentration.

  • 10% gelatin (250 bloom or greater)
  • 1.2% Speedball india ink or 1.6% Black Cat india ink
  • 4% sugar
  • Water to make
  • 25 ml of isopropyl alcohol mixed 50/50 with water to make 50 ml (an optional ingredient added at the end which can help dissipate bubbles more quickly if you intend to use the glop shortly after mixing)

Art paper sizing

A 7% gelatin solution is easy to coat, sets up quickly to allow you to hang the paper to dry, and gives a reliable printing surface if the paper is thoroughly and consistently coated and the gelatin is hardened. Thinner or less concentrated sizing will provide a more matte finish but will be more prone to developing frilling or blisters on the print when developed.

Hardener for gelatin sized art paper

This is a topic of it's own see my blog post.

Clear

A 3% solution of sodium or potassium metabisulfite will clear the residual dichromate stain from the print. Soak the print for approximately 3 minutes or until the stain clears. Wash in clean water for several minutes afterward. The clearing solution can be reused.

Hardening gelatin sized paper

This post is a running record on how I have hardened gelatin for sized art paper. I generally coat my papers with a 10% gelatin solution using an RD-95 coating rod for a .25mm wet hight thickness. To my surprise, I have found coating papers and finding good hardener to be as challenging as making my own carbon tissue. I have currently settled on using formalin as it works wonderfully and is perfectly safe when used outdoors in low concentration.

Formalin

Know to work well in all ways, but toxic. Formalin hardens perfectly and doesn't leave a cast in the paper or gelatin. For these reasons, I avoided using formalin for a long time, but finally decided to give it a try for my last batch of papers. Following recommendations from others I used a 2% solution of formalin 37. That's a 2% working dilution of a 37% stock solution. I hardened the papers in a tray outdoors and pre-soaked the papers before putting them in the formalin. 

The combination of the dilute solution and soaking outdoors made left almost no odor. So, I felt confident that I wasn't putting myself at risk. I soaked each paper for about a minute and put them on a clothesline to dry. The formalin can be reused. I am not sure how to judge when it would be expended. So, there is little environmental impact. 

The results were perfect. The gelatin was perfectly hardened and there was no change in the color of the paper. The process itself was also very easy. Combined with soaking and drying outdoors for safety, formalin will be my go to solution for hardening from now on.

Glyoxal

It's far less toxic than formalin and hardens well, but does produce some yellow stain in the paper. Much of the stain washes out in development and clearing but not all. My method to date has been to put about four drops in 75ml of gelatin, and this works well. I would like to try brushing it on after coating and drying. This would minimize my exposure to it and keep my gear from getting as gummy while coating.

Alum

The key is knowing the difference between potassium alum and chrome alum. Potassium alum is relatively harmless. It's apparently the same stuff they put in the little pencils used to stop bleeding from shaving knicks.

However, it does not harden well and is difficult to wash out of paper. So, it can be good for hardening paper that will be used as a final support in a double transfer carbon print. However, when I tried to use it for a single transfer, it hardened the gelatin in the tissue during the mating to the support and ruined my prints. 

Chrome alum apparently hardens well but is far more toxic. I have been told it can also leave a nasty blue cast to the paper.

Gluteralhyde

Never used it, but given it's toxicity, I would probably just use formalin.