My First Carbon Transfer Tissue

Black jelly.jpg

Making the Carbon Transfer Tissue

Mixing the Jelly

This is often referred to as 'glop', but since it is just gelatine, sugar and pigment, it is basically a jelly - so I prefer to to call it that

I will do the calculations for 1,000ml (1 litre), but the proportions can be scaled down. 10% m/v requires 100g of gelatin

Proportions are:

  • Gelatin 10% m/v
  • Sugar 4% m/v
  • Lamp black powdered pigment 3.1% m/v
  • Isopropyl alcohol 2.5% v/v

Ingredients

  • 100g Gelatin
  • 1,000ml de-ionised water
  • 40g plain sugar
  • 31g powdered lamp black pigment (for my first go)
  • 25ml isopropyl alcohol

Equipment

  • Double boiler
  • Photographic thermometer
  • Measuring jug
  • Weighing scales and weighing dishes
  • Stirrer

This is the technique I am going to follow:

  1. The Gelatin Bloom Add the full 100g of gelatin to 300ml of cold de-ionised water and leave to bloom for 20 minutes. You will see the gelatin expand and soak up all the water. Then add the remaining 700ml of water and stir in before heating.
  2. Heating the gelatin I use a simple double boiler technique, which involves a pan of water on the kitchen stove, with a suitable container that holds the gelatin solution without spilling. The gelatin will dissolve completely at 50°C and the trick is to measure the temperature using a kitchen thermometer. I heat the pan and never let the water boil and slowly watch the temperature rise to 50°C. The trick is to keep it at that temperature while you coat. (By the way, normally when making jelly I use the microwave to great effect, I can't see why it could not be used here with care).
  3. Adding the sugar Add 40g of plain white sugar and stir until dissolved
  4. Add the pigment I prefer to add powdered pigment - I want to use both white (titanium dioxide) and black (carbon, lamp black). Some of the recipes I have are for India ink, and they suggest 14g for 1 litre. Though René Smets suggests 15g for only 250ml of gelatin solution, which is 60g per litre. I am going to start at the concentration I use in my gum prints, which is 31g per litre for lamp black and 320g for titanium white (its physical density seems to be about ten times that of lamp black). This is stirred slowly into the gelatin solution. I tend to not have problems with the titanium dioxide or lamp black with gum - however, if it does not mix easily, I could add it to a 25ml of the gelatin solution and add that back when fully mixed
  5. Remove micro-bubbles Add 25ml of 100% isopropyl alcohol to help remove bubbles. Thymol is often added as a preservative, but I propose to mix only as much as I need and, therefore, don't intend to keep the jelly. Though in future I may want to. Then leave for half an hour for the bubbles to dissipate 

Amounts for the First Attempt

  • Size of yupo paper 642mm x 450mm
  • With magnetic strips this reduces to is 562mm x 370mm
  • Magnetic strip is 0.85mm high
  • I need a jelly volume of 177ml (53ml for the gelatin to bloom - 124ml to top up)
  • Gelatin 17.7g
  • Sugar 7.1g
  • Lamp black 5.49g
  • Isopropyl alcohol 4.4ml

Making the Tissue: using Flexible Magnetic Strips

I quite like the word 'tissue', I'm not at all sure it is correct, but it does sound very Victorian, which seems appropriate (though in my Chambers' dictionary it has "Paper coated with gelatine and pigment (photography)", so may be it is up to date as well)

I use a magnetic whiteboard - large enough to take A2 sheets, which is the largest I can get into my light-box

Ingredients

  • Warm pigmented jelly - volume calculated to suit

Equipment

  • Whiteboard
  • Spirit level
  • Wedges and shims
  • Magnetic strips
  • Water spray bottle
  • Squeegee
  • Kitchen paper for blotting
  • Comb
  • Sharp point or scalpel blade
  • Hanging area - line and plastic pegs

This is the technique I will follow to make the tissue:

  1. Levelling the whiteboard Using shims and wedges, adjust the whiteboard so that it is completely horizontal using a spirit level
  2. Mist the whiteboard Using a spray bottle, dampen the whiteboard and squeegee the tissue substrate to the surface and blot away excess water
  3. Lay down magnetic strips Using the magnetic strips, cut to size if necessary, fence the required region on the tissue substrate to accept the jelly when ready. Make sure there are no gaps between strips
  4. Pour the warm jelly Calculate the exact amount of jelly needed to fill the fenced off area. Remember 1ml is 1,000 mm2. Pour the entire amount of warm jelly into the middle 
  5. Spread the jelly Using a normal comb and working quickly spread the jelly making sure it gets into all the corners
  6. Leave to set The jelly should set when it cools, which should be 10 to 15 minutes. The magnetic strips need to be removed, but first run a sharp point or scalpel blade around the outside of the jelly to make sure it is not sticking otherwise the jelly may tear
  7. Hang up to dry The tissue is now ready to be dried - hang it up and wait 24 hours
  8. Storing the tissue The tissue should not be left hanging out for too long - it is best stored flat, but can be rolled but no tighter than 75mm diameter. I've seen suggestions that it can be kept in the freezer.

Results

It may not be the prettiest jelly ever made - but I love it

It is 615mm x 410mm, so it is quite large. My plan is to cut it up and do a series of tests with my Stouffer stepped negative.

Lessons Learnt

  1. Starting with such a large sheet proved to be difficult - I should look to make smaller tissues rather than cut a larger one
  2. Warming the whiteboard before pouring the jelly would have helped - I plan to warm it as well as wet it next time
  3. My mixing of powdered pigment was not as good as it could have been - I will explore inks and look to better pigment mixing later