While surfing the web, I found the following report from the National Industrial Chemicals Notification and Assessment Scheme following an application from Shell Chemicals to import a product they call Neodol 1 - 9.
The interesting thing that this product is a surfactant used by Colgate - Palmolive in the manufacture of liquid dishwashing detergent and appears to form 19% of their product. The other interesting thing is that another name for this product is Polyethylene glycol monoudecyl etherundecyl ether. I'm not an industrial chemist and I don't know if this is the same chemical that we know as Polyethylene Glycol (PEG) that has been used previously for successfully stabilising timber and, as older Brits and Aussies will know, for preserving eggs etc during WW2, but at least it would appear to come from the same family.
I am not sure if other detergents use the same surfactant but it would seem possible and may suggest a reason that the LDD system works and, given the percentage used, why the amount of further dilution is critical.
It is of interest that elsewhere I discovered that dishwashing detergent for automatic machines uses a different type of surfactant to minimise frothing.
I have no idea of the age of the report.
The link to the report is: