My Ultimate Panning Procedure
[by Martin H. Milas]

The objective of this essay is to describe a panning strategy for retrieving and handling fine gold from concentrates that utilizes only hand powered techniques and only non-mechanical, relatively inexpensive pieces of equipment capable of reducing raw concentrates to virtually pure gold stored in a vial.

        It is what I consider my ultimate panning procedure because it has several side benefits. It can be applied in the field for fairly quick results without resort to any power driven machinery.  This, in turn, makes it especially useful in a sampling plan where it is important to keep track of fairly accurate results. It also is inexpensive and eliminates the need to haul around cumbersome batteries, bowls, wheels or other panning aids. Additionally, it is a pleasant and relaxing way to break up the rigor of those days when I take my aging body into the field and must impose upon myself recovery times in between dredging runs or sweaty periods of heavy pick and shovel work while drywashing in the desert.


        The special focus of this article is how to deal effectively with concentrates that pass through a #30 classifier. Classification: The first step is to classify the concentrates after I have employed my primary means of concentration. Panning is most efficient and most reliable directly in proportion to my ability first to reduce my material to units of essentially the same size. This is so because the existence of grossly unequal eddies is one of the worst enemies of maintaining the relative stability of material while the mass is being worked by water action. One of the causes of destabilizing water action consists of objects that are much larger than the other objects near it. Large objects cause water moving over and around these larger pieces to lose laminar flow, ie, the water gets diverted into different directions in the local vicinity of the larger objects and this affects the ability of a panner to maintain sufficient control of the mass. This degree of control is essential, especially during the completion phases of each pan of concentrates, as will be seen. Ideally it would be more effective to pan only the material that has passed through a #30, but not through a #50 classifier than material that only has been passed through a #30. But such attempts at near perfection are quite labor intensive and the following procedures work quite well even if a #50 screen has not eliminated the tiniest particles.

        Drywashing is one primary means of initial concentration, typically in a desert locale. Others involve water such as sluicing or dredging in a creek or river. My technique for the initial classification of concentrates is basically the same for wet or dry materials despite the fact that the shape of the individual pieces and specks of gold itself is grossly different. Desert gold typically is chunkier than river gold which frequently is hammered into extremely thin pieces. But there are minor differences. I will go through each scenario in turn.


        After a drywashing run in a desert locale I empty the riffle tray into a rectangular plastic dishwashing basin that is the proper shape and fit to catch all the concentrates and deep enough not to lose material in windy conditions. I take this tub to the tailgate of my 4X4 pickup, which is a comfortable height for me to work at without developing back spasms or neck kinks. I insert a #4 classifier screen into a green 14 plastic gold pan (I am describing the color of the pans only to enable the reader to follow the process better).   I begin with a #4 because anything that will not pass through easily can be located with a metal detector. Thus, I always discard this material in the same spot and check it with the beeper prior to departure.
Next, I pour the contents from the green pan through a #8 screen that is placed in a blue 14 pan. I use my gloved hand to rub the material briskly against the metal mesh in an effort to break up hard, dry clay balls or caliche fragments. After shaking through all of the loose material, I pour what remains in the classifier screen into the empty green 14 pan. Then I bang the classifier screen down pretty hard into the green pan. Doing this 3 or 4 times knocks out most of the little pieces that got stuck in the grating of the classifier. The contents of the green 14 pan then are poured into a 10 finishing pan and set aside. I repeat this process through my #12, #20 and #30 classifiers so that when I'm done I have five finishing pans ready to be panned, consisting of what would not pass through a #8, #12, #20 and #30 plus what did pass through the #30). Panning the first four of these five groups goes very quickly and the remaining gold is transferred into a common vial with fingers or tweezers after counting the results. The lead is picked out for proper disposal later. It is the fifth batch of concentrates (composed of particles small enough to pass through a #30) that presents the greatest challenge. Details on dealing with this very fine material is described in depth below.

        Classifying wet concentrates only differs a little in that everything must be done in water instead of dry and the volume of material is much greater. I either set up a sufficiently large and deep basin on my tailgate and fill it two-thirds with water or I set up at the edge of the waterway where the water is fairly calm and I can comfortably sit or kneel and have a sufficient working surface to place the pans, screens, etc. Material is poured into a classifying screen which, in turn, is placed inside a 14 pan. I prefer to use low profile classifiers because these are easier to grip and hold together against the inside surface of the gold pan. The pan and the screen inside, while held tightly together, then are submerged. I proceed to agitate the contents by swirling and jerking them, taking care to keep the bottom edge of the classifier held tightly against the inside surface of the pan so that none of the concentrates can escape. The smaller material quickly passes through. Then the bulk of the wet remains are carefully poured into an empty 14 pan. The remaining particles that remain adhered to the inside of the classifier then are banged into this same 14 pan so that now all the concentrates that did not pass through the classifier are in this 14 pan. From here I front pan some of the material down until I can transfer the remainder into a 10 finishing pan. A variation of the above, when dealing with substantial volumes of concentrates, is to insert the classifier screen into a plastic bucket. If I'm in a dredging production mode, then I only use buckets and set these aside for later processing during my lunch break and after my evening meal.


        Front Panning
: Almost everyone has a front panning technique. But first it is instructive to examine the different types of underlying forces that are at play and to share some techniques and strategies that can harness these forces rather effectively, especially when dealing with sub #30 fine concentrates. The two primary forces I rely upon to reduce my concentrates are gravity and magnetism. I will deal with each, in turn, as they relate to my panning strategy.
The motion of objects has three measurable quantities: force, mass and acceleration. Mass is different from weight. For example, the weight of any object is different when the object is on the moon as opposed to the earth, but the mass remains the same. Since we do no panning on the moon, for our purposes we can speak of the weight, the mass or the density of objects interchangeably. Also, for our purposes we may refer to acceleration as speed. Speed becomes important in panning when I create a momentary state of suspension because some materials will gather speed faster than others. In a vacuum, of course, all objects regardless of mass accelerate at the same rate. But in water, objects of greater weight relative to the water can overcome the resistance of the water (and also the friction of rubbing against other solid objects in suspension in the water) and accelerate faster than lighter objects and thus are better able to slip downwards towards the bottom of the pan. Finally, I will refer to various ways that kinetic energy (a type of force) can be transmitted in the medium of water.

        The idea of panning is to get the lightest things out of the pan while keeping the heaviest things inside. This sorting process depends upon creating conditions inside the pan that will permit gravitational influence to allow some objects to behave differently than others. I can do so most effectively by placing the solid objects in momentary suspension, ie, by creating a momentary separation between the solid particles in my pan. By doing so we create a momentary opportunity for the heavier, denser things to slip past other particles and fall faster than the lighter things through the resistance of the water toward the gravitational pull exerted upon all them equally from the center of the earth. If I am skilled at doing so, then I can control the location of the heaviest things in the pan by forcing them to find their way to the place in the pan that is closest to the center of the earth.
In the panning of unconcentrated materials that consist of a wide disparity between light and heavy particles I can fairly easily achieve a crude division of the particles by agitating the contents of the pan such that the upper layers of material contain the least dense particles. I then tilt the pan under water and skim this layer of light material off the front of the pan a few times before resettling the remaining material and then creating yet successive layers of light materials that are skimmed off, each time first by creating some forward inertia and then by tilting the pan slightly lower in the front while smoothly drawing the entire pan rearwards and slightly upwards back over the same angular plane as the tilt of the pan. Each layer of lighter material becomes progressively thinner as I work my way down. I call this process front panning. The initial front panning of concentrates, however, isn't so easy. This is so because much of the material already is dense. Thus, I need to focus on a more efficient way to create the necessary momentary suspension of the entire mass and I need to do this many, many more times per unit of time than when panning unconcentrated material. The key to doing so lies in the principle of the wave and mastery of its application to heavy concentrates.

        Energy can be transmitted in numerous ways. Think of how a bullet is forced out of the barrel of a gun. Or of how billiard balls are broken up with an impact. Or how a screw is turned into a hole. Now think of a long, coiled telephone wire (those of you old enough to remember fixed position telephones with long curly cords) that you have stretched out somewhat while chatting on the phone. Note that it takes very little energy for you to create a wave motion in this extended length of curly cord. And when that wave motion reaches the other end of the cord, an incredible amount of the original energy remains, ie, there is very little loss of energy when transmitted over great distances by employing a wave. Note how far a tsunami can deliver its energy. This exact same principle can be put to work in a gold pan.
I do this on the tailgate of my pickup by employing an old fashioned porcelain, oval wash basin filled about two-thirds with water (about two gallons). The 10 plastic finishing pan has about an inch of empty space from side to side at the center of the oval basin. By banging the pan repeatedly against the sides of the metal basin I create shock waves of energy that are carried along through the water, momentarily putting the mass of particles in suspension with each successive shock wave that I generate. First, I tip the front of the pan slightly downwards as I move it forward and simultaneously bang it from side to side. Then I gradually tip it back to near level as I continue banging. At this point I gradually retract the pan rearward toward the center of the basin. In this way I have settled the gold and I have created a gold-free upper layer of material in the finishing pan. After repeating this process a few times I can begin skimming off this upper layer, but more carefully than when working with unconcentrated material. In a creek I can accomplish the same effect by utilizing a pair of boulders or large rocks to bang the finishing pan between or against. One difference, however, is that the oval shape of my metal basin permits me to vary the frequency of the shock waves in a way similar to how the pitch of a guitar string can be changed simply by varying the position of pressure application with one's non-strumming finger along the length of the string. Higher frequencies are created when the finishing pan is almost as far forward as it can go in the oval basin. It is here also that I can create the greatest number of shock waves per second because the distance of the edges of the finishing pan to the sides of the basin is shortest. Conversely, the highest energy shock waves (and thus the greatest degree of suspension) can be created in the middle of the basin because the extra distance permits a greater build up of speed before hitting the side and reversing direction.

        Front panning, of course, has its limitations in that no amount of care can ever succeed in completely getting rid of all the black sands while keeping fine gold inside the pan. The reason for this is because it becomes virtually impossible to continue creating thin enough layers to scalp off the top by going over the forward edge without pushing some of the gold over the same edge. A pan with built in riffles, of course, completely rules out any possibility of getting rid of all the black sand. Rather, a completely different strategy must be employed. This consists of the art of back panning.


        Back Panning
: Back panning is a term I use for the process of getting rid of unwanted black sand off the back edge of the pan while keeping the gold pinned in the crease along the front, bottom edge of the pan. Some additional forces are utilized -- magnetism and a phenomenon I refer to as capillary cohesion, plus wave cancellation. I will explain how each of these come into play.
The biggest problem at the end stages of panning down sub #30 material to pure gold is the difficulty involved in avoiding swirl. The reason I say this is because one little mistake will send your carefully panned concentration of fine gold spilling over a wide area and toward the rear of your pan where you do not want it. Think of swirl as an unwanted, rather overpowering horizontal wave of water that is strong enough to break up the fragile web of cohesiveness that keeps the concentration of heaviest particles formed in the crease at the forward edge of the pan from breaking up. The best way that I have found to pan down to a point where almost all the black sand and lead is eliminated is by a gradual drawing of the unwanted contaminants straight down to the bottom edge for disposal. After many years of practice and experimentation I finally hit upon the concept of wave cancellation as a potential solution to solving the swirl problem.

       
Wave Cancellation: Wave cancellation best can be achieved in a simple gold pan. By this I mean a pan that has a single side sloped down to a broad and flat bottom. Complex pans that are constructed with an additional straight drop at the bottom and pans with a narrow bottom do not work well for my techniques. This is because swirls and uneven waves result. Riffles are totally unnecessary for back panning. Wave cancellation requires a careful balancing of the pan to maintain a level axis upon which to backwash the unwanted black sands to the rear of the pan. The capillary cohesion forces (related to surface tension forces) that allow your solid material (where your fine gold is buried) to stick together are very weak, so our movements at this point must be rather slow and careful. The proper way to position my body is the key to success.
This position is assumed immediately after I have eliminated as much unwanted material as I safely can by front panning. I then reconcentrate the remaining material into the forward crease of the pan by vigorously (but not overwhelmingly) banging or tapping it quickly from side to side while under water. Then, very deliberately and very carefully I tilt the rear of the pan lower than the front so that all the water drains back to the back edge of the pan while capillary cohesion keeps the wet solid concentrates held together in a bunch at the forward edge of the pan. At this point I dip the rear edge of my 10 flat-bottom finishing pan into the basin and allow in about a cup or maybe a little more than a cup of water.

        When I back pan I hold the pan straight out from my body as I lock my elbows at my sides and never move them, not even a little bit, while I grasp the finishing pan firmly with both hands. The only movement occurs at the wrists. They must work in synch in order to maintain the required level axis of movement, ie, a perfectly horizontal plane held perpendicular relative to the center of the earth. Once the proper position is established I begin dipping the pan forward so that the water begins to advance towards the front of the pan.
By maintaining the pan perfectly level as I continue to tilt the pan forward, the water advances against both curved sides at an equal pace. Once the water reaches the mass of concentrates the water surface is split apart. Each of these advancing water edges becomes a wave which carries with it a roughly equal amount of energy. The curvature of the pan forces the advancing water to wash up over and around the collection of black sand (and gold) concentrates and when they finally ‚€œkiss‚€ at the very center of where the concentrates are positioned, the energy they are carrying cancels, thus eliminating any significant swirl. It is at this moment that I begin to bring the rear of the pan back down to allow the water to backwash over the concentrates and carry some of it away. This drawing down movement is executed at a somewhat brisker speed than when the pan is tipped forward. When done properly the advancing flood of water does not break up the clump of concentrates. But on the back dip movement the retreating water carries particulate matter straight down towards the rear of the pan. Doing this repeatedly gradually draws down a pile of black sand to the rear of the pan. This contamination must be washed out occasionally by carefully submerging the rear of the pan under water while tilting the front of the pan up just enough to permit me to gently swish the unwanted black sands off the rear edge and down into the basin (or into a water filled pan or bucket if I want to accumulate the black sands for other uses). Now I repeat the process until I start seeing glints of gold. That tells me it is time to use the magnet.

        Use Of The Magnet
: The biggest danger in using a magnet is the accidental loss of gold that gets trapped between the particles of magnetite. This happens when too powerful of a magnet is brought too close to the concentrates. A large mass of magnetite that jumps to the magnet will carry with it particles of gold. However, it is easy to avoid trapping the gold.
I take advantage of the fact that both gravitational and magnetic forces act upon magnetite, while only gravity acts on gold. Thus, no force is directly attracting the gold particles to the magnet, while gravitational force is constantly tugging the gold away from the magnet toward the center of the earth. By not allowing the magnet to get too close to the black sand, I vigorously swirl the edge of the magnet just above the surface of the concentrates which I previously have scattered across the entire bottom of the pan. The result is that the resistance of the water prevents the particles of magnetite (which are too dispersed) from trapping any gold. Removal of the magnetite makes the remaining panning fairly easy, albeit somewhat time consuming. I just keep drawing off more and more waste particles until only gold and lead and a few specks of black remain. This is the time to employ the pipette.

       
Use Of A Pipette In Transferring Fines: I once again bang the remains into the forward crease of the pan, but this time I then draw the pan rearward and then thrust it forward with a short jerky movement. This causes the majority of lead and black stuff to partially separate from the greater mass of gold which tends to stay further forward in the pan. This fine gold then can be sucked into the pipette and held there by adroitly tilting the pipette at an angle slightly higher than level so that gravity keeps the gold particles inside until I am ready to deposit them into a vial. This is done, not by squirting, but by inserting the tip of the pipette into a water filled vial, then raising the pipette to vertical and simply allowing the gold to fall down into the vial. This will occur very quickly the moment that contact is made between the tip of the pipette and the surface of the water in the vial as long as no bubble of air remains at the tip of the pipette.


        The pipette also can be used to separate the last remaining small stubborn black sand or lead contaminants from the gold. To do so I employ the basic principle that heavier objects accelerate more rapidly through the resistance of water than lighter particles. This nifty little trick is accomplished by drawing all of these remains into the pipette, then immediately when the bulb has fully expanded and the particles no longer are being drawn into the pipette, I quickly bring the bulb end of the pipette up to vertical and simultaneously move the opening of the pipette in a straight line under water across the bottom of the pan without applying any squeezing pressure to the pipette.
This maneuver causes the heaviest things to accelerate and exit first from the column of water remaining in the pipette. After the greater amount of gold falls out the opening, then the lead and then the rest of the particles fall out in descending order of density and weight. Thus, I now have a short line of mostly gold particles which I can suck back up into the pipette in a much less contaminated state for deposit into my vial. Repeating this maneuver a few times, is effective at eliminating the heaviest of the contaminates. Alternatively, I can use the pipette as a sort of pressure hose to herd wayward gold particles together or, alternatively, to blow particles of contamination away from the last of the gold with little puffs of water pressure. This takes a little practice. With patience it becomes another valuable technique.

        
Additional Tips And Comments: Desert gold, due to its chunky shape, occasionally presents a special problem even when the pieces are smaller than #30. If the pieces are sufficiently round or log shaped, small as they are, they will roll and migrate downhill along with the black sands. This means that during back panning care must be taken because the weak force of capillary cohesion is insufficient to hold these wandering rascals in the mass when the black sand layer gets too thin. There are a few solutions. The easiest is simply to use your gloved finger to push back the escapees each time they make a getaway. A better grade of tweezers easily can pick these out if they are in the #30 to #50 range. The pipette also can be used to isolate these in a separate pan for temporary holding.


        While dredging it is important to keep verifying whether I am in the pay zone and whether the gold is getting bigger or smaller. Another important aspect of dredging applicable to me is that I need to force myself into taking periodic breaks because I mostly dredge alone and I tend to get fixated, lose track of time and not only over exert myself, but also get into a hypothermic state. So I use my noon food break not only to eat but also to rest (aerobically) and warm up. This is when I do some panning. I set up several 3 ounce glass vials and label each with a size designation (#8, #12, etc.). As I work my way through the panning process I get a specific result, already broken down in terms of different sizes and amounts of each that I easily can see in the vials.

        The miner's moss in a dredge or sluice can catch and retain a lot of gold that does not rinse out with water alone. A simple solution for finding the pieces large enough to be metal detected is to leave the miner's moss overnight on a boulder or log to dry. In the morning turn a plastic tub upside down and lay the moss across it. Then detect it, pulling out the pickers with tweezers (most of it will be metallic junk, but I sometimes get a picker or two).

        In the desert it is especially relevant to use protective gloves. The desert alkali soil cracks my skin to the point I can't handle a silk tie without sticking to it like velcro. My bride does not appreciate Mr. Sandpaper Hands either. I use somewhat oversized chemical resistant gloves with super wide openings. These enable me to get in and out of them quickly, plus they hold up for a long time. Working the tweezers or pipette, however, are best done with bare hands.

        There are ordinary tweezers and then there are really good tweezers. If you inspect the tips of the tweezers with a magnifying lens you will be able to discern whether the tips are aligned or not or if there is slippage between the tips. If not perfectly aligned or if not sufficiently stiff, there are two common results. The first is the inability of the tweezers to grasp and pick up the smaller, flatter pieces of gold. The second is the chip shot effect -- a tendency to shoot your small nugget or flake across the room. Other factors to consider in selecting a pair of tweezers consist of whether the tips are magnetized and whether the tensioning force is comfortable and how wide or narrow the tips are. I carry two pairs with me. One magnetized with tips about one-sixteenth inch wide and one not magnetized with very narrow, pointy tips. The latter allow me to work in an environment filled with magnetically attractive particles. Too much or too little tensioning pressure impedes my fine motor control. High end tweezers can cost up to $20 a pair, but to me, they are worth the investment. Try several out to suit your hand and finger before making a purchase.

        A jeweler's loupe or small magnifying glass is extremely useful, but there is a huge variation in quality. I find a seven power to be best for me. Spending a little extra to get an undistorted, wide field of vision is well worth the money. Everyone's vision is a little different, so before making a purchase be sure to compare and contrast by trying out numerous different sizes and brands until you are personally satisfied with what you are able to see.

        A set of different sized small plastic funnels is a great assist when transferring fine gold from container to container. Whenever I make these transfers I always work over a sheet of standard sized computer paper which is placed over a full sheet from a newspaper. This is because a mistake can spill the gold a surprising distance. I fold the sheet down the center lengthwise to establish a well defined groove. Then I spread it out flat. The reason for this is in case there is some spillage, then I can just pick the entire sheet up, gently fold the edges so I wind up with a deep vee. A plastic funnel then can be inserted into a vial. Next I insert one end of the deep vee into the mouth of the funnel and gently raise the other end of the deep vee until all or almost all of the tiny gold particles have been transferred into the vial. Any remaining particles that are stuck to the paper can be dislodged by gently tapping the underside of the deep vee with a finger. That pretty much covers the gist of my ultimate panning technique. It works well for me, but it took me years of experimentation and practice to perfect it. If any of these ideas or insights help others with improving their panning skills, then it will have served its purpose.

Copyright © 2008-2013 Martin Milas/PCSC