“New Tank” is a mystery. I don’t make a big deal out of it when teaching but it is something that marblers come to expect to see fairly regularly in the early papers that they “pull.” That’s why I plan to try new things or practice techniques for the first two or three sheets – I also tend to use cheaper paper for those sheets.
Let me show you what it looks like in a combed pattern:
See how much of the white in the red rectangle is misshapened? That is new tank. You can also see it when the paint has been dropped but not combed because the edges of the drops are often misshapened with irregular “spotches” of clear tank.
Sometimes there is a lot of new tank and sometimes I don’t see any. The explanation I have been given is that the various chemicals – the alum, the carrageenan, and the paint — need to “marry,” that is, interact a little so they work well together. New tank occurs when those chemicals have not yet interacted together. However, this does not explain why sometimes “new tank” doesn’t seem to appear while at other times it does… Regardless of what the explanation is, it usually goes away after 2 or 3 sheets.
If your tank doesn’t go away, then I believe that there is something “polluting” the carrageenan long term. It might have been in the container where you mixed it or in whatever you used to actually mix the carrageenan. In other words, some chemical from past uses of your equipment has mixed into the carrageenan and is causing the ongoing problem. This is why it is so important to keep your carrageenan mixing equipment safe from potential pollutants. The most obvious of these “potential pollutants” is soap! Soap is a surfactant that lowers surface tension between liquids. Surface tension is why the paint on the vat does not blend and we are able to make patterns in it. So, when washing your equipment never use soap! While this may seem like an extreme requirement (e.g., having special equipment for mixing carrageenan); most dedicated marblers are willing to do it because they want to control as many of the factors that can effect marbling as possible.
New tank in the first few sheets is, however, to be expected and cannot always be controlled – it is just something you need to work around.