I agree with Stephen583 that running clean pay dirt is beneficial. The reason why is simple.
Gold has a much easier time dropping out of the laminar flow when the fluid it is suspended in is less viscous.
Some compositions of bank run material can thicken the viscosity so much as to cause gold to stay in the laminar flow all the way down and off the end of a sluice.
Anyone running a sluice, especially a recirculating system, should be well aware that too much viscosity causes gold loss no matter what sluice or mats they have.
Also any prospector worth his salt knows that clumps of clay will rob you of some of your gold.
Can you make up for your losses by running more dirty material instead of running less clean material? Perhaps and perhaps not. There are two schools of thought on this subject. In my opinion it depends upon the size of the gold. Bigger and rounder..YES. Smaller and flatter NO.
Given the choice I would much rather run clean classified material than dirty unclassified material and work less as Stephen583 suggests. But really it depends upon how much muck is in the bank run material as well as the quantity and size and shape of the gold in the material.
The point of classification is to keep the larger gravels that bounce down the sluice from knocking smaller particles of gold back up into the flow to be swept out of the sluice. Another reason is that any large rocks or gravels that stop in the sluice will cause a faster flow around them thereby sweeping more gold back up into the flow or preventing it from dropping out in the first place. Easy to prove. Just push a finger down into the flow next to a small piece of gold and watch it be swept away.
When all the particles in a sluice, pan, miller table, blue bowl, etc. are closer to the same size, gold always wins easily. There again easily proven.
As far as wd40 goes, personally I would not want it in or on any of my recovery equipment for the simple reason that like any oil it will cause flour gold to collect and float on top of the water and be lost. That is a fact and it's easy to demonstrate. Sorry Stephen583, But I have to disagree with you on that one.
As far as the home made clay-b-gone goes Stephen583 is absolutely right on the mark.
Stephen583 is also right about dish washing liquid it is a surfactant (reduces surface tension and stops flour gold from riding on the surface ) but of course due to sudsing you only use a drop or two. Laundry detergent also works just use it sparingly. Using too much Jet-Dry will also cause sudsing.
Stephen583 you are welcome around my campfire anytime along with all you other hombres, that is if y'all can keep down the bickering.
Go for the Gold
GG~