[wayne zabel]

I understand the theory of Wick Back ,but can someone explain why its a commom occurence on low profile carpets.I can understand it on a normal carpet when a stain can go deep into the pile ect and come back when wet.but where is that stain in the low profile carpet?

I hope this doesn't sound a daft question.

[Neil Williams]

but where is that stain in the low profile carpet?

As the base which get's more wet than normal longer profile carpet.
Due to airflow restriction (because of the solid backing) you tend to extract less fluid pro rata than a normal carpet . Normal carpet is porous at the base.
Hope that helps although it's the abridged version of what should be a long reply.