Some marblers use the original seaweed even today, to create their size (the solution on which colours are spread is known as size). You can also find these art pieces available for sale. It is a real hassle job as compared to a commercial art carregeenan as it needs to be chopped and then dried, boiled and cooled. Later it is strained and filtered so that the resulting size turns brown instead of turning transparent, which also prevents you to see the colours.
You can get carrageenan one pound as well as half pound arts and you can buy it according to the size you want to make. The half pound bag can let you generate almost 300 papers and large bag can produce over 600 papers.
Till now, you must have had in your ice cream, cheese, yoghurt, chocolate milk etc.; you can prepare it in your kitchen blender. This is how you make the half pound gallon size
Put one teaspoon of carrageenan powder with one level of tablespoon into a blender cup. Fill cold water till the top. Put your mixture on highest speed and blend it well. Then the foamy mixture you get should be poured into a container of half gallon and add water till the top. Shake it a little to mix it well.
Allow the mixture to stand in the refrigerator overnight for minimum four hours. This needs to be done in order to allow the bubbles pop. It will come out of your blender in the form of foam and it requires settling more before it turns into liquid again.
The mixture lasts for at least 10 days when stored in the refrigerator. It stays for only a day or two if left at room temperature. After that, it will become watery as it loses its thickness.