Glop is the popular name for an emulsion used to coat the tissue used in carbon transfer or carbro printing.

I make small batches with a basic 500 ml of distilled water at a time, for me this is sufficient to make 4 tissues at A3 size.

The formula I use is –

500 ml distilled water

50 grams 250 bloom bovine gelatine powder

35 grams refined white sugar

10ml glycerine

10 ml isopropyl alcohol

6 drops of thymol

 

I slowly mix the gelatine powder into the 500ml of chilled water in a container (I use a big pickle jar about 750ml in size) and leave to stand for 30 minutes.

I then put the jar into a water bath at 41 degrees C and leave for about an hour to get evenly to the bath temperature.

I then stir in the sugar and add the glycerine, using a plastic syringe.

I leave for ten minutes in the water bath and then add the isopropyl alcohol and 6 drops of thymol

I normally add the pigment I require at this point, but I also make batches which I can refrigerate and store without pigment.

The next step is to put the mixed glop into a vacuum chamber with the lid off the jar. This chamber must be heated carefully and kept at 39 degrees C – I run the vacuum for at least 40 minutes.

Pigment

The amount of pigment added depends on the colour and the make.

For black I usually use a commercial Indian ink – there are many makes and the blacks vary from a mars black to almost a van dyke brown. I have found the densities vary a lot and I have needed as little as 8 grams of ink for 500ml to 32 grams of  ink for the same volume.

I am experimenting with different palettes of colour – I am not a fan of blue as a colour and play with the Apelles palette, so my separation negatives and separation prints are often different from the conventional RGB (cyan, magenta, yellow tissues) – I use a lot of water colour “inks” to make tissues and the quantity to make a suitable tissue varies a huge amount, from 30 grams to 100 grams of ink – in the larger quantities I have to adjust the volumes of ingredients in the glop.

As an aside, to make the colour separations for the palettes I am playing with, I can make the “gels” for the filters for the panchromatic B&W negatives from the tissues I make – they are real “gels”.