First let me say I'm a rookie so keep that in mind, however my son and I took a class from a reputable establishment and the instructor specifically said if you don't classify in a stream sluice you run the risk of a larger rock literally bouncing gold out of the traps and riffles and blowing it out the end. I classify down to 1/4 in our sluice and classify the cons again to 1/8th.
We wet classify everything so I can't see the problem with gold sticking to the rocks. And since we are noobs we prolly spend more time than we should checking the classifier for keeperites, and leaverites than we should.

James

Classify, Classify, and classify again. Even a dredge or high banker has some first stage classification built in, be it the grizzly bars or the expanded metal at the top of the sluice. I am embarrassed to say I recently ran 12 buckets of good material through a brand new sluice un classified and while I found some gold, I have wonder what I lost.

I have red both the P&S, and the article in the mag, both have good points.

It is fact,
the smaller the feed material into the box, the less water flow needed through the box to clear the box = better chance of fine gold to find a place to hide.

There is a balance point between classifying down smaller, taking time away from feeding the box, possibly reducing production.
I classify to 4mesh = 1/2" , I don't let it blow through, I see some really small stuff in my clean outs.
Only you know the answer based on your operations.

As far as gold sticking to rocks, I always make sure to wash off any mud that may be clinging on rocks when moved.
As stated before, if running a river sluice, get the material wet on some level before running.

Not so sure large rocks in a sluice being beneficial, need more info to decide.


Bill

When running my sluice I run everything .Most of the rocks will not go down the sluice as they are to big .I just wash them .When everything id dry material I classifi down to 1/2 .That is small enough .But as you might see everyone has their own way .

When running my sluice I run everything .Most of the rocks will not go down the sluice as they are to big .I just wash them .When everything id dry material I classifi down to 1/2 .That is small enough .But as you might see everyone has their own way .Buy the way as you feed you can take out the larger rocks and wash them.

With the 4 foot DK box I used to run, and the A52, I used to go with 1/2", but with the 30 inch, with flare, Royal backpack I use now, I go to 1/4".  Bigger rocks I wet wash in the same 1/4" c;assifier into a pan and then either pan that out while alternating with feeding the box and giving it time to clear, or feeding it into the sluice as well.  All the dirt and such gets the 1/4" treatment, dry, into a bucket and then fed to the box.  After dry screening then I wash out the classifer into a pan and check that.  Been getting good recovery down to less than fly speck stuff.

 

Like everyone says above, the boxes are designed to run as clear and cean of obstructions as possible.  Anything that disrupts or interferes with the clean flow can cause some losses.

Having been a prospector for 54 years, and a believer in classifying, I would have to it all depends on the size of the gold in the area. I'm working an area now that has gold from 1/32 to .002. I screen down to 1/8 if I'm going to run it thru my Cube. If I take the material to the river and run thru a sluice, I screen to 1/4 in. I want to use as slow a flow as possible. I then place an 1/8 screen in the sluice box and let the river do the rest. All large mines classify, if they didn't they would end up with a real mess and little gold. You also have to decide whether it's worth the trouble to take it down as small as possible, or, are you going for production?

when highbanking, I pull larger rocks out by hand and wash them separate. Everything else goes in. Panning must classify or gold gonna escape to freedom. Ditto with a stream sluice. If a bigger piece gets caught at a riffle or trap, it'll displace the smaller gold.