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Post  Jack outwest on Wed Apr 17, 2013 9:06 pm

Although I've mentioned this before is there anyone who agrees with this hypothesis , and why ? Please . scratch

GOLD PAN and the Kress hypothesis
The importance of the angle of slope of the circular wall is implicit in all US patents for gold pans, but only in the 1950s did any inventor properly examine the effect of the slope on panning performance. It was Bruce Kress who first developed a hypothesis for wall slope in 1957 in US patent #2,797,809. The Kress hypothesis might be reworded as:
The angle of inward slope of the circular wall of a gold pan should be in the range of 18 to 26 degrees; less than this and the contents of the pan are likely to remain inert, more than this and the contents of the pan are prone to collapse regardless of the size of the particles or their density.

If the Kress hypothesis is correct, then the majority of North American pans have outer walls that are much too steep for ease of efficient use. Yet thousands of recreational miners, prospectors and geologists continue to use steep-sided pans. Possibly the Kress hypothesis is erroneous; more likely the hypothesis is correct but compromised by the overriding desire of the panner to have a central flat area of maximum size to contain the maximum ore and water during the initial wetting, disaggregating and sorting. Only in the later stages of panning does the Kress hypothesis become critical, after the volume of solids and water in the pan have become greatly reduced. Tests and detailed observations are required. In the 50 years since the Kress hypothesis was propounded; more than 10 North American gold pans have been patented but all ignore it.
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Post  Gold Miner on Wed Apr 17, 2013 9:22 pm

Have a look at national/international panning comp 'images' look at the 'pans' used, within the rules, but differant! ..... it might enlighten you Jack?
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Post  Digginerup on Wed Apr 17, 2013 9:38 pm

I probably know too little about panning to make an informed opinion yet jack but it's all good food for thought, scratch however there seems to be a wide variety of pans used with success around the world both modern and traditional.

Wayne. cheers
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Post  Jack outwest on Wed Apr 17, 2013 9:52 pm

Thanks Guys for your reply’s but I was not interested in pans so much Embarassed but angles study
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Post  shyneesteel on Thu Apr 18, 2013 10:49 am

I think,the steeper the angle the more the particules compact making classifying harder in the initial stages but after a while it would be height of wall that matters.To short and you would lose some of what you were after maybe. Dave

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Post  mungoman on Thu Apr 18, 2013 12:18 pm

Just my two cents worth - when assessing creek bank integrity in river rehabilitation, we were taught that there is an optimum degree where alluvial, colluvial and aeolian erosion is managed and ceases- the term is 'angle of repose'. This differs according to soil type and soil texture.
So, thinking about gold and the material that it's found in, it would determine the needed angle of the wall of the pan and the velocity of the water used to negate the adhesive factor of the soil carrying the gold. Here are some materials and their angle of repose shown.
I'm wondering if the gold pan can be improved. If they can, I don't think that that all important slope would be changed much.



Material (condition) Angle of Repose (degrees)
Ashes 40°
Asphalt (crushed) 30–45°
Bark (wood refuse) 45°
Bran 30–45°
Chalk 45°
Clay (dry lump) 25–40°
Clay (wet excavated) 15°
Clover seed 28°
Coconut (shredded) 45°
Coffee bean (fresh) 35–45°
Earth 30–45°
Flour (wheat) 45°
Granite 35–40°
Gravel (loose dry) 30–45°
Gravel (natural w/ sand) 25–30°
Malt 30–45°
Sand (dry) 34°
Sand (water filled) 15–30°
Sand (wet) 45°
Snow 38° [6]
Urea (Granular) 27° [7]
Wheat 28°



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Post  Jack outwest on Thu Apr 18, 2013 12:25 pm

Yep your right I think Dave , gravity will work against you with steep angles , also agitators can’t perform when compacted &
the speed factor of ( separation ) slows down more & more with angle increase scratch

Mungoman ' that's very interesting about the sand angles - Sand (dry) 34°
Sand (water filled) 15–30°
Sand (wet) 45°
Thanks Very Happy

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Post  mungoman on Thu Apr 18, 2013 1:18 pm

Jack, it is curious...I was taught that it was all about saturation, permeability, porosity, sediment size and sediment shape which would determine slump factor (angle of repose) as saturated sediment has got to have a lesser angle because it is in a more fluid state, which is imposed on more by gravity. i suppose all of this will determine the needed angle of the wall on a gold pan. I wonder How good a Wok would be at panning out gold...?
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Post  Jack outwest on Thu Apr 18, 2013 3:23 pm

Hi Mungoman ,
That's the information I need Very Happy it's not about pan wall slope so much but how saturated material including odd shaped rocks allow gold to penetrate using spread angles .

As for a wok ? probably would work fine if care was taken when ditching the less heavy stuff .

Cheers
Jack .
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Post  Jack outwest on Sat Apr 20, 2013 12:15 am

Gold Miner wrote:Have a look at national/international panning comp 'images' look at the 'pans' used, within the rules, but different! ..... it might enlighten you Jack?

Check out this goose for enlightenment Laughing
https://www.youtube.com/watch?v=3tw428PbvnQ

Gold Miner I do look at the angle of those pans used by the winners in most comps , what I see are low angled wall pans = winners .
Thanks for the conformation Wink

Jack .
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