Turkish/ebru marbling, the colorful style known for its use in bookbinding, does require a few special materials for good prints.
1. Carageenan – this is used mixed with water for the “size”, the liquid on which the ink or paint floats. It thickens the water so that the ink will sit on the surface, and helps the ink spread at a reasonable rate. It costs about $2-3/oz. and is usually sold in 8oz or 16oz bags at art/craft stores or online.
Carageenan used to be more common, as it was used for thickening food products (like ice cream); there considered to be some toxicity, however, and it is not used as much these days. However, it’s very safe to work with, so you can use kitchen supplies to measure and mix it.
2. Alum – this is mixed with hot water as a mordant to get the finished pattern to stick to the paper or fabric being marbled. It costs about $1/oz and is also sold in 8oz/16oz bags at art/craft stores or online.
It was used in pickling, but it is also somewhat toxic so it is not commonly used in food preparation nowadays. It does contain aluminum and comes as a fine powder, so be careful to keep it out of your eyes and try to avoid touching it much. The process of mixing it with water and sponging it onto paper doesn’t seem too risky; I sometimes wear gloves and always wash my hands, just in case. The significant health risks from alum generally involve long-term exposure, not intermittent handling. Check safety warnings on packaging to be sure.
Carageenan and alum are the only specialty ingredients, and while they are not too cheap they also last a long time.
Alum is mixed at about 1 Tb. per cup of water, and 2Tb/2c. will go a long way sponged on to paper.
Carageenan is mixed at 1.5Tb. – 2.5Tb per gallon of water, and since you can keep using the tray of size during a marbling session, it tends to last a long time too.
Preparing the carageenan:
In a blender, add 1.5 Tb. of carageenan powder, and then fill most of the rest of the space with hot water – leave an inch or so empty to avoid splattering.
Mix for 1 minute on medium – it will turn into a foamy, sea-water-smelling mixture.
Pour this into a container that can hold a gallon of water (I use a clean milk jug, the cap is convenient too) and then fill the container the rest of the way with hot water. It will need about 4 hours to settle (the foam and bubbles need to settle out), and then it should pour like thick water, not lumpy.
It can be stored in the fridge for a week or so, and I have had good luck storing it at room temperature for several days with no problems. I usually use it at room temperature; for me, cold carageenan has turned lumpy and impossible to use.
If it goes bad, it will smell like dirty seawater and will not work well.
If it is just lumpy, you should be able to add a little hot water and re-blend it in batches (it’s hard to pour the lumpy stuff into the blender, and my blender sure doesn’t hold a gallon). After it settles out again, it should return to a thick liquid and be ready to use.
Preparing the alum:
Put 2Tb. alum in a container that will hold 2 cups of water.
Add warm water, mixing while you do so, and then add increasingly hot water, continuing to mix well. I do this because it just requires turning up the hot water on the tap. Others heat it on the stove, or just mix it into water at one temperature or another. If you heat the mixture on the stove, do not use a pan you will be eating from, for safety.
Once you have your alum mixture, prepare paper by wetting a sponge with it and running the sponge vertically over the paper one side to the other until the paper is damp. It doesn’t need to be soaking; you just want to make sure the surface you will be printing onto is damp.
Make sure as you lay sheets of prepared paper down, that you know which side has alum! I just lay them all down alum side up and make sure to turn them for printing – but you can also lay them face down and pencil an x on the back or mark the unprepared side in some other way.
Press the stack of paper under a board or some books, so that they stay flat.
I have had much better results using paper which has dried first – but some marblers use the paper while damp. See what works for you.
Once your size is settled and your prepared paper is dry (if you are using it dry), you can begin to make your prints.
Troubleshooting and Resources
I had trouble at first with ink just sliding off the paper after printing, and for me it made a big difference to use carageenan at room temperature at 1.5Tb:gal (I also tried cold and 2.5Tb:gal), and to use dry alumed paper.
If you have trouble getting prints to come out well, try adjusting how wet or dry your paper is, which paper you are using, and the temperature and strength of the carageenan. Some say humidity is a major influence on carageenan too.
Be aware too that there is more than one kind of caraggenan – Kappa carageenan is not as good for marbling, but it is a little cheaper. I bought mine before I discovered this, and have been using it successfully, but it tends to be harder to manage as temperature changes, and can gel solid if it cools off; it is also more likely to repel the ink than proper marbling carageenan.
A blog with marbling tutorials and information:
Jaquard marbling supplier how-to:
Jaquard’s brochure has some good troubleshooting tips.