GOLD PANS of every shape
What is a GOLD PAN?
Gold pans belong to the group of gravitational gold recovery devices driven directly by hand without handles, gears or other mechanical means. The group includes not only the classic gold pan but also the bowl-shaped batea of South-Central America, conical dulang of South-East Asia, ninja bowl of Mongolia, bucket of Kyrgyzstan, lotok of Russia, rubber mat of Mongolia and other traditional devices, as well as recent innovations such as the Trinity Bowl, Hex Pan, Grizzly Pan and Litrap Pan.
The term panning has been used for all these devices, without first determining if the motion of the operator and device are similar, and if the actual concentrating process is comparable.
The term panning is good for all washing devices that are directly driven by hand movements; but counterproductive in assessing devices as diverse as the pan, lotok, batea, dulang, bucket, ribbed mat and washing-up bowl.
These are not GOLD PANS...
The following account is restricted to the classic gold pan of North America and its heirs.
North American GOLD PANS
GOLD PAN history and origin
The device arose during the mid 1800s and spread with remarkable speed. How the gold pan originated is a mystery, but 3 alternatives merit consideration:
u from a modification of the Spanish/Mexican batea:
The batea is an open conical dish, often with a small central depression. The batea had been widely used in south-central America for centuries before the gold rushes of North America and the batea should have immediately rushed north but did not. The batea was originally made by carving and turning timber to produce a wooden thick-walled wide slightly conical dish capable of floating or at least possessing neutral buoyancy. Later a partial shift to a thin-walled batea made of metal occurred, the metal allowing the batea to be heated for cooking and to drive off mercury from amalgam to leave gold.
u technology transfer from elsewhere :
The third alternative is that the miners gold pan was imported ready-made from elsewhere. This is plausible, and there is evidence that the novices in the 1840s gold rushes in California gained know-how about equipment from seasoned placer miners arriving from the 1830s gold rush of Georgia. In which case they brought miners pans with them or said "frying pans are the next best thing".
u from a domestic frying pan minus its handle:
The author suggests the North American gold pan arose from a domestic frying pan by the simple expedient of removing the handle. It is for style a frying pan is flat-floored; it ensures the maximum surface contact with a hot stove, and stability on the stove and later on a table. Look at the picture - its a frying pan with the handle removed, being used as a gold pan in Kyrgyzstan by a local villager.
Earliest GOLD PANS of North America
Gold pans were widely used in North America since the 1830s but the first was patented only in 1861, so the first 30 years of innovation await study by historians. By 1861 North American gold pans were diverse, of "sheet-iron, tin or wood" and John Brock of Chicago wrote, "The sheet-iron pans are mostly made by machinery by being pressed into shape from a single piece of sheet-iron of proper dimensions. Some are made by the old plan of cutting the sheet-iron and seaming together. Some are made of wood, generally turned."
GOLD PANS for dozing, scooping and, scraping
Many prospectors in the past used the pan as a dozer, scoop and scraper without recourse to spade or screen. This minimized baggage on foot and horseback. The dozing and scraping capability has been largely lost by modern pans. Unable to doze or scoop, the modern pan tends to be marginalised as a prospecting tool unless used with a shovel or wash-plant.
Why did the GOLD PAN fail to spread worldwide?
North American gold pans are strongly favoured by recreational miners and mining companies in North America, Western Europe and the English-speaking world, but are very rare elsewhere. The failure of the gold pan to spread worldwide merits study, and may indicate some technical limitations of the North American gold pan, not just cultural resistance.
GOLD PANS: US patent search
A laborious patent search unearthed 39 US patents for gold pans awarded between 1861 and 2003. None seem to have been awarded since, although the Trinity Bowl is Patent Pending, making a grand total of 40 gold pans. In spite of the search, perhaps half a dozen or more US patents for long-forgotten gold pans remain as yet undiscovered.
GOLD PAN defined
The author recommends the following narrow definition for a gold pan of North American type:
A shallow pan consisting of a flat (or nearly flat) floor bounded by a circular wall that slopes outwards to the circular edge of the device. The device is driven manually, by grasping the pan in both hands.
Inventions not strictly GOLD PANS
Of the 39 US patents for gold pans, all belong to the diverse group of gravitational gold recovery devices that are driven directly by hand without handles, gears or other mechanical means. This excludes the large array of inventions that are mechanical pans based on the reverse helix, commonly known as gold wheels. Ten of the 39 US patents for gold pans fall outside the narrow definition of a gold pan:
u Dana's Ore Washer and Concentrator (#481,550) is close to a lotok in being a trough moved to-and-fro.
u Miller's Alluvial-Gold Washer (#569,113) is unique, being unlike any other gold recovery device known to the author. It is half a cylinder that is rolled to-and-fro.
u Stoodley's Pan for Washing Gold (#618,918) is a deep bowl with a hemispherical, rather than flat, base.
u Campbell's Assaying Device (#667,969) has an elliptical bottle shape for assaying rather than panning.
uJonhansen's Miners Washing Pan (#799,059) is a South American batea and therefore lacks a flat base.
u Hussey's Miners Gold Pan (#840,333) is an oblong set of trays primarily for to-and-fro motion.
u Klein's Method and Device for Gravity Separation of Particles (#3,407,933) is unique, being unlike any other gold recovery device known to the author. It consists of a flexible cone which on kneading causes gold to migrate to the bottom, but lacks a flat base.
u Litrap's Gold Pan and Classifier (#4,289,241), Gordon's Gold Pan (#4,400,269) and Ashcraft's Hand-held Classifying Device (#6,095,342) are oblong panning devices intended mostly for to-and-fro motion.
GOLD PAN motion
The design of the gold pan determines its unique motion.
The standard motion is imparted by grasping the edge of the pan by both hands simultaneously, and moving the hands to induce the geometric centre of the pan to move in a circular to elliptical path. During its orbit, the pan may be held level or tilted away from the operator. In addition to simple orbits, many other motions can be imparted, including rocking, tapping, knocking, twisting, spinning, to-and-fro, side-to-side, tick-tock etc.
GOLD PAN walls
To understand and classify gold pans, it is helpful to note the angle of slope of the circular wall that surrounds the flat central area. Among the US patents, from the mid-1800s to the present day the preferred angle of the inward slope of the circular wall is in the range of 40-50 degrees, with a preference of 45 degrees. No gold pan seems to have a slope steeper than 55 degrees, and few had slopes less than 25 degrees.
GOLD PAN bottom
The effect of the slope on the overall dimensions of the gold pan merit attention. The gentler the inward slope then, for a pan of a given diameter, the smaller the area of the flat central bottom. Therefore the gentler the slope the less the pan conforms to a North American pan and the more it starts to resemble a South American batea. If the diameter of the pan is increased, then the steep-sided version resembles an artisanal gold pan made by removing the handle from a modern frying pan, as seen in Kyrgyzstan.
If the pan is small, or its circular wall is high, then the gently sloping variant may entirely lack a flat central area, and the term batea seems obligatory. Indeed if the circular wall is steep and a central flat area is lacking then the term dulang is more appropriate as seen in Laos.
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.
GOLD PAN speed
Screening reduces the volume before panning, increasing the volume processed. Current fashion is to pre-screen, but many prospectors past and present use the pan as a dozer, scoop and scrape without pre-screening, merely avoiding boulders and rejecting oversize by hand. Pre-screening prevents the pan being used in this manner, and may cause the pan to be replaced by a rocker, small sluice or similar portable device capable of a screening and processing much larger volumes. Some inventors insert screens in or on their pans, notably Sletcher (1897), Hardwick (1907), Nicolai (1934), Remais (1993) and Rosman (1997). This cuts the volume panned, but renders difficult viewing the pan contents and invites delay while the screen is detached for cleaning.
GOLD PAN baths
Gold panning with the pan submerged in a stream is tiring for a gold panner and invites risk of skin damage, and indeed water-borne diseases and in cold water numbness and frostbite. Placer companies solve this by installing panning baths. Baths are too cumbersome for lone prospectors, solved by Ord (1913, 1919) adding handles that keep the hands clear of the water. This innovation has been lost.
GOLD PAN size
One way to maximise gold production is to use a large pan. Indeed the traditional North American gold pan is about 18 inches in diameter. The reverse has happened with modern pans being much smaller. For every inch reduced the area reduces disproportionately and so too does the useful depth of the gold pan. In the past it seems a panner would use as large a gold pan as possible for initial rough panning and hand screening, and then tip the much reduced volume of upgraded slurry into a small pan for actual gold recovery. It follows that the small pans would also find favour by placer companies for upgrading concentrates from wash-plants and become popular among recreational miners wanting to travel light and with a requirement to upgrade concentrate from small sluices. By comparison the market for large-sized North American gold pans has dwindled and manufacture is limited. Ord (1913a, 1913b, 1919) shows that a large heavy pan in possible if the pan is supported by cables from above, so allowing the panner to control the panning motion in the normal manner without much physical effort. This innovation has been lost.
GOLD PAN for dry panning
The traditional North American gold pan is intended for use totally submerged in water for the first part of the panning process and with copious water available for the later stages of panning, especially if troublesome clay is present. Several inventors found ways to greatly reduce the water required for the panning process. Ord showed some of his innovative designs (1922, 1923) require far less water than a normal pan. The same pans can function with dry sand without any water at all as can the pans of Smith (1962) and Rosman (1997).
GOLD PAN empty from underneath?
Scientific tests are lacking, but experienced panners assert that most gold settles during the first few swirls of the water in the pan, and most the effort and time is devoted to ditching the lights and excess water slowly and expertly to avoid throwing out the gold also. Several inventors circumvent this labour by inserting a gold removal mechanism to the base of the pan, notably Kendall (1863), Ord (1919), Nicholai (1934), Streng (1953), Legg (1981) and Morgan (1982), and it is also resorted to by some inventors of hand-held to-and-fro pans such as Ashcraft (1996).
GOLD PAN with screens
Screens inserted in or on gold pans featured on patents by Sletcher (1897), Hardwick (1907), Nicolai (1934), Remais (1993) and Rosman (1997). This cuts the volume panned, but renders difficult viewing the contents and invites delay.
GOLD PAN and fine gold recovery
Most gold pan inventors claim improved recovery of fine gold using their innovation. While this may be assumed correct to a degree, the multitude of patents addressing the same issue indicated lingering dissatisfaction.
Earliest GOLD PAN patents - 1860s
Brock's Improved-mining Pan (1861)
The first US patent for a gold pan.
The central floor of the pan is covered by a sheet of copper. Mercury locks on the copper as a Cu-Hg amalgam whose mirror-like upper surface amalgamates with gold particles in ore added to the pan. The objective was to lose less mercury and recover more gold.
Kendall's Paragon Gold Saver (1863)
A pan to cut mercury loss and increase fine gold recovery.
The outer pan is a standard North American pan, modified to have a gently sloping floor to ensure mercury, amalgam and gold drain to a central pocket. This sloped central floor makes the device transitional with a batea. The inner pan fits tightly inside the outer pan and their rims are sealed together. The inner pan is floor-less - ore and mercury falls uninterrupted into the outer pan. The inner pan serves as a huge riffle-like dam that retains the gold, mercury, amalgam and most of the black sand when the device is tilted to shed water and lights as tailings.
GOLD PAN patents of the 1890s
Sletcher's Gold-washing Pan (1897)
The first US patent for a modern-style gold pan.
A single riffle ("rib") circumnavigates the pan about a third the way up the inwardly sloping wall, to retain heavies. The floor of the pan has 8 banana-shaped troughs to catch heavies prone to slide out of the pan when it is tilted north by the panner. To empty the contents of the troughs the panner rotates the device through 90 degrees in order that one end of each banana is now tilted north. The heavies in the escaping material are then retained by the riffle rib that rings the pan wall. This particular pan is designed to face north or 90 degrees from north (i.e. east or west) but not south; it cannot be termed a Janus pan (see below).
Moore's Prospector's Pan (1899)
The second US patent for a modern-style pan.
Half the inwardly sloping wall is smooth, half is covered with about 10 small riffles. The inventor claims his pan is a combination, achieving the same as two different pans. During the first stage of panning the riffled portion is tilted north away from the panner, and lights are ejected while gold is retained by the riffles. Later, to catch small gold, the panner first rotates the pan 180 degrees so that the smooth portion of the pan is now tilted north. The inventor claims that it is easier to see small gold on the smooth surface than on the riffles. When a pan can face in diametrically opposite directions (north and south) for accomplishing different tasks, the author suggests the term Janus pan.
GOLD PAN patents of early 1900s
Collin's Prospecting Dish (1900)
A gold pan with a riffle ("rib") added.
The solitary riffle is "about three-eighths of an inch in width and is placed about an inch from the top", round half the circumference of a plain pan. The riffle is a horizontal plate, and when the pan is tilted north with the riffle hemisphere to the north, then the riffle ledge stands vertical as the wall is inclined at 45 degrees. The riffle ledge creates a distinct pocket for trapping heavies. Final cleaning is done by the panner first rotating the pan 180 degrees to recover small gold on the smooth wall of the pan tilted north. This is a Janus pan.
Tobin's Prospecting Pan (1900)
A gold pan with a defensive shield.
The panner tilts the shield end down to the north, and this allows rapid aggressive panning through loose wet gravel with little fear of ejecting gold from the pan. The shield also serves as a single giant riffle underlain by a huge pocket that retains material. Four rows of holes allow water to flush and drain the lower part of the shield. The shield is braced by a bracket at each end and a line of bolts along its downward edge. After the rough panning, the panner flushes the contents of the shield into the central flat disk. Final cleaning is done by the panner first rotating the pan 180 degrees in order to recover small gold on the smooth wall of the pan tilted north. This is a Janus pan.
Johansen's Miner's Washing Pan (1905)
A batea to show the difference from a gold pan.
An improvement to what the inventor calls Mexican bateas by carpeting the innermost part of the cone of a batea with copper sheet. Technically this requires some effort, and a pre-requisite specified by the inventor is to first beat a central depression in the apex of the cone, so that the copper sheet can be inserted while still keeping smooth the internal wall of the batea. The inventor stresses the need for the copper to be as pure as possible and specifically free of iron, and copper rivets to be used to secure the conical copper sheet firmly in position. Furthermore that the heads of the rivets to be beaten as smoothly flush as possible with the shape of the batea. The inventor was a resident of Dutch Guyana (= Surinam) in South America, where the batea remains widespread among artisanal gold miners.
Hardwick's Miner's Pan (1907)
A pan with a hand-cranked unit to agitate fines.
The unit is slotted into the base of the gold pan. The uppermost layer is a coarse mesh metal screen held in place by four arms. Close below the coarse mesh is a medium mesh metal screen, and beneath that is a fine screen made of taunt cheesecloth or similar fine material. Beneath the set of coarse, medium and fine screens is a perforate metal disk that helps to support the screens and its large holes allow the fines to fall unimpeded to the bottom of the gold pan. The inventor includes a ring magnet attached to the perforated disk to catch and hold magnetic particles. Particles that fall through the three screens and past the magnet accumulate on the floor of the gold pan. The panner turns the handle periodically to disperse any packed material.
The patent breaks new ground for panning, for here in miniature is a gold pan, three screens, magnetic separator and an anti-packing stirrer. This gold pan merits building by a precision engineer to allow proper evaluation, and has some features that anticipated the modern Rotapan of Australia.
White's Pan Riffle (1908)
This looks like a simple pan: it is not!
The main feature is a slotted apron termed a "riffle" occupying about a fifth of the circumference of the rim. It is debatable if the apron can be termed a riffle , as it also functions as a screen. A sturdy flange is secured around the top of the remaining bare rim of the gold pan by a series of spring clips. This flange is a simple giant riffle, although the inventor declines to call it so. By ponding water and sediment, the flange reduces the risk of throwing away valuable concentrate with the tailings. It also channels concentrate towards the slotted apron. Much depends on the ability of the slotted apron to retain heavies while allowing water to flush away tailings. By lifting each of the spring clips the entire assembly is detachable. Although the inventor does not mention it, this allows the gold pan to be dual purpose: first with the giant riffle attached for rough panning, and then with the giant riffle removed for final gentle panning. This is a Janus pan of sorts.
GOLD PAN patents of Edward Ord II
In the history of American gold pans, one inventor towers above all others, Edward Ord II. His father Edward Otho Cresap Ord was born in Cumberland, Maryland, in 1818. After receiving a West Point appointment from the District of Columbia, Edward Ord graduated from the military academy in 1839. He served in the Seminole War, the Mexican War in California, and the American Indian wars. In 1854 he married Mary Mercer Thompson. Ord saw extensive action in the American Civil War, most significantly as commander in one of the North's earliest victories at Dranesville, Virginia; as a prominent participant in the siege of Vicksburg; and as a major force in the final drive against Richmond and Petersburg that culminated in Appomattox. After the war, Ord commanded the departments of Arkansas, California, Texas, and the Platte. In 1881, he retired from the army. Edward Otho Cresap Ord I died in Cuba in 1883. He is buried in Arlington National Cemetery.
Edward Otho Cresap Ord II was born on 9th November 1858 at Benicia Barracks, California. After attending public schools in San Francisco and Omaha, he was appointed to the U.S. naval academy in 1876, only to withdraw a year later. In 1879 Ord became a second lieutenant in the 22nd infantry. He soon saw action in the American Indian campaign in Texas and the campaign against Sitting Bull in 1891-1892. His 22nd infantry was among the first American troops to enter Cuba in the Spanish-American War in 1898, and his unit experienced heavy fighting. Following duty suppressing a rebellion in the Philippines, Ord retired from the army on account of disabilities sustained in Cuba. Ord continued his military pursuits as a military aid to the Arizona governor and served on the Mexican border. In April 1912 and April 1913 Ord filed patents for innovative gold pans, duly awarded in 1913. In 1918, he retired to California and was awarded more patents for gold pans in 1919 and 1922. Edward Otho Cresap Ord II died on the 4th April 1923 at Eagle Rock, California.
Ord's Miner's Gold Pan (1913)
Three innovations transform a basic pan:
1: raised central platform: this creates a circular channel around which the heavies concentrate during the swirling of the gold pan, and was the forerunner of later patents such as the blue bowl. Tilted in the usual manner to the north, an oval dimple in the trough trapped the heavies. This is a Janus pan.
2: exit spout: lowering a section of the outer wall makes a broad "spout". Final panning is facilitated and small gold trapped in a linear dimple. The inventor notes that mercury may be added to the two dimples if desired.
3: swinging handles: these allow the panner to keep hands out of the water during panning.
Ord takes his innovative pan further:
4: swinging ropes: adding ropes allow the pan to be submerged and the panner keep hands out of the water and yet swing the pan by tugging on the ropes. This is less tiring, allows greater throughput and is potentially industrial-scale.
5: central vanner: in Ord's earlier invention, the raised central platform served only to create the circular channel. Now the platform is gently sloped to its centre for cleaning up the final concentrate. Ord termed it a "vanner" and it resembles a miniature batea in simplicity and gentle slope.
Ord's Gold Miner's Pan (1919)
Ord developed his pans further and in 1919 was awarded a patent for "certain improvements over the gold pans shown in my similarly entitled prior United States Patents...". The innovations had three main goals:
1: "so constructed that a whirling, spinning or centrifugal motion may be readily imparted thereto..."
2: "..this motion arrested and reversed in direction quickly in order to effectively and expeditiously recover gold..."
3: "...for receiving and separating large quantities of heavy material, in which the pan is adapted to be suspended from above and allowed to rest on a central pivot point about which the operator may conveniently rotate [the pan]."
A pair of stout metal rods straddles the gold pan. Grasping them the panner can impart a sudden reversal of motion to the pan. The metal rods also allow ropes to be attached from above to suspend the pan. As in the 1913 patent this enables panning to be less tiring for the operator and allows a much greater throughput.
The once-flat central platform of 1913 has evolved through the 1913 batea-like "vanner" for final upgrading into the 1919 batea proper for bulk concentrating. A choice of simple cone or convex-down cone is added.
Pay gravel is put on the platform and the circular channel filled with water. Panning begins by tilting the gold pan from side-to-side to induce water to pass in waves over the platform, "in this way washing the original sample gently out of the vanner until nothing remains there except the metal contents of the original sample, the sand and gravel having been washed into the annular channel..."
Removing the gold concentrate from the centre of the platform is via a tap hole and discharge plug from below. The discharge plug serves as a central pivot upon which the pan is "rocked for certain separating purposes". This allows a wobbling action, a tilting action or a controlled spin with little effort.
The circular channel is now the dump site for tailings. Indeed Ord suggests an optional screen over the central platform and to deflect oversize to the the channel. Larger stones are removed by hand, and then the tailings rewashed by circular motion of the pan.
In a further innovation, much of the outer wall of the pan is fluted to impart "repeated shocks" to disaggregate resistant clay. Recovery from the central channel is by tilting north to trap heavies in a dimple (with a tap hole) and intercepting escaping gold by four oblique grooves.
The 1919 patent also presents a modification to facilitate "laboratory work". This has a narrow channel added to circumnavigate the central platform near to the top of the rim. Adding this extra channel enables, "repeated washings from the outer channel to enter readily the centre vanner and permit oil floatation tests on sand concentrates...". This is a tantalising remark. It may be that Ord was experimenting at the time with oil floatation methods of gold recovery, especially of fine gold. Alternatively Ord may have revealed in his off-hand remark a novel way of checking for fine gold by forcing it to float.
Ord's Gold Pan (1922)
Pans for use with or WITHOUT water.
Pans "capable of use either with the sand wet or dry as conditions may require." This extends panning to arid regions.
The innovation begins with a plain pan into which a central rib is inserted to partition the pan into two chambers. The top of the rib is lower than the rim of the pan to prevent the contents sloshing out during panning. As the rib approaches the pan wall, the rib flares outward as ears, the ears being gently concaved inwards to form corners or pockets where heavies can concentrate.
A minor improvement is the modification of the rim of the pan by one or more trough-like "guide grooves" to permit the pouring out of residues left in the pan.
The inventor comments that the pan wall may be sloped straight or somewhat concave, and may have an optional flange "for convenience in manipulation."
In a variant, a deflecting rib is added to a compartment, and the opposite compartment has one or more pockets countersunk in the bottom of the pan at the base of the pan wall to catch heavies and to hold mercury if used.
In a second variant, the partition is no longer a simple rib but a curved rib "oval in cross section, adapted to save the finest gold dust". Instructions are not given on how to use this version of the pan. Again one compartment holds a deflecting rib while the other compartment contains a linear groove as trap.
In a third variant, the pan is elongate, deviating markedly from the circular plan of a classic pan. The central partition is tapered; one end as high as the pan wall, the other end much lower. Again, one compartment has an inwardly projecting tapered rib, wedged in cross section, its outer portion having concave ears to create pockets for trapping heavies. The opposite compartment contains a linear groove as trap.
Ord comments, "the pans may be made polygonal or irregular in contour if desired" but does not discuss them further and none are illustrated.
Ord's Gold Pan (1923)
Another pan for use with or WITHOUT water.
Material is put in one compartment of the divided pan. Water is added to cover the sand. The pan is held by the handle and tilted slightly toward the opposite side and a gentle agitation applied. A swirling motion is also used. Heavies fall to the bottom and the lighter sand washed into the other compartment.
The handle "enables the reaching for and scooping up sand or gravel. When once charged with sand, this can be shifted all into one side and then water added." Opposite the handle is "a point added to enable breaking through snow or any crust" and "a pick point" to clear obstructions. If the pan is large for large work, the shovel end acts as a pivotal support and the handle a lever to operate the pan.
GOLD PANS from Ord to World War II
Nicolai's Miner's Pan (1934)
A screening pan inserted into a gold pan.
The inventor claims that this increases gold production for less effort. The device is radially symmetrical so this is not a Janus pan.
The screening pan is raised somewhat from the gold pan by means of internal legs. The screen is made either of perforated metal, or a metal mesh screen. Recovering gold from the gold pan is via a central cup detachable from below.
Ryan's Mineral Washing Pan (1934)
A simple design with ease of manufacture in mind.
The device is a simple flat floored pan whose inclined wall bears S-shaped corrugations to serve as riffles. Four such riffles are illustrated in the patent. Each riffle stops slightly short of completely circumnavigating the pan, so leaving a narrow smooth channel. This makes it a Janus pan.
The channel narrows towards the rim, and the inventor says its main function is when cleaning the pan after the end of the panning process, and also for final upgrading of concentrate.
Danills's Gold Pan (1934)
A pan with sharp riffles extended about half way round.
This makes it a Janus pan. Each riffle is a ledge about half an inch wide. Three riffles are suggested for an 8-inch pan and six for an 18-inch pan. The bottom of each riffle is parallel to the flat bottom of the pan, whereas its top side is "substantially at right angles to the side walls". The sides of the riffle meet in a sharp edge.
The object of this riffle is "to make it impossible to lose any of the gold or heavier metals, also to increase the speed of panning ninety per cent."
After the gold has settled in the pan, "the pan can be tipped up to an angle of 60 degrees and the pulp all discharged without losing any of the gold or heavier metals."
Boekel's Gold Pan (1939)
A pan with a ring slot.
An invention based on the observation that gold collects in the crease where the side wall meets the flat floor. The inventor replaced the crease with a bead-shaped slot circumnavigating the pan in a ring to retain gold that otherwise is prone to be inadvertently ejected during panning. After panning has been completed, the pan is tilted north and clean water used to flush the trapped gold from the ring slot into a tapering spout that is a continuation of the slot as a depressed area of the side wall. The gold and water is thereby transferred safely into a container ("gold flask").This is a Janus pan.
GOLD PANS from World War II to 1970
Streng's Direct Gravity Recovery Gold Pan (1953)
A pan with a novel funnel trap.
The novel feature is a circular funnel trap feeding a cylindrical chamber ("cup") accessible from below by turning the screw thread. Instead of the cup, a conical plug ("finger") can be screwed in and the trap then being confined to the funnel.
The pan floor is gently domed to encourage material and water to concentrate around the contact of the floor with the side wall, and so be the main site of heavies to concentrate, inexorably destined for the funnel trap. The inventor mentions the floor can also be flat but did not present such a drawing so the author has duly added it.
Kress's Gold Pan (1957)
A pan much flatter than a conventional pan.
The inventor claims the gentle slope enables faster panning and easier recovery of small gold. The patent includes the Kress hypothesis reworded thus: "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."
A second innovation is a tight fitting fine metal mesh screen.
A third innovation is "a canvas or other matting material" put under the screen, clamped taunt between the screen rim and the pan wall to aid trapping fine gold.
Smith's Gold Pan (1962)
A pan for panning with or without water.
Besides making efficient use of sheet metal and low-cost manufacturing, the pan is said to improve gold recovery and enable "much faster" panning than a basic gold pan. The pan is for use either with or WITHOUT water, the first patent since Ord in 1923 to make such a claim.
As an example, it is a 15-inch pan with flat bottom 8-9 inches in diameter, with the pan wall sloping at 30-35 degrees. The inventor says, "obviously the bottom of the pan does not need to be flat but can be somewhat concave if desired."
The rim of the pan is bent over outwardly in order to strengthen the rim. However one segment of the bent-over material is bent back again to form an inwardly directed rim riffle, termed a "trap".
A further innovation is corrugated riffles in the pan wall below the rim riffle, to agitate material being panned and encourage heavies to be trapped either in the corrugated riffles or in the rim riffle. The author suggests the corrugated riffles act like a miniature concentrating table and direct heavies into the rim riffle. This is a Janus pan.
GOLD PAN patents from 1970 to 1980
Stephenson's Gold Pan (1974)
A pan linking conventional pans to gold spirals.
A single riffle is integrally formed in the wall of the gold pan and the riffle spirals downwards from the rim of the pan to the edge of the flat floor of the pan. The riffle has a pronounced overhang on its lower edge to catch and hold heavies while the lights wash over it.
The gold pan is used as a bulldozing scoop on the bottom of a stream, with the riffle end of the pan tilting north. During the dozing, the spiral riffle retains the heavies. Alternatively the gold pans can be swirled underwater in the traditional panning manner, or swirled out of the water.
Lawrence and Jacobson's Miner's Pan (1975)
First patented see-thru gold pan.
The first patent for a gold pan made of low-cost thermoplastic, and the first to specify clear plastic so gold can be seen from below.
The floor is not flat but slopes gently to a central trap. The trap has a curved bottom, facilitating settling by rocking.
The gold pan is submerged and shaken in an orbital panning manner; pausing to remove oversize by hand. The gold pan is then slowly raised out of the water, at the same time rocking the pan north-south, ejecting the water and lights northwards. The panner then lifts the gold pan to check for gold in the central trap, looking through the clear plastic. If no gold is visible, then panning is resumed, If gold is visible, the panner tilts the pan north to channel the contents of the central trap up a series of tiny riffles that retain the heavies while the water and lights continue north along the channel to discharge from the pan rim. This is a Janus pan.
Lagal's Apparatus for Separating Material
by Specific Gravity (1979)
Gold pan of dark green thermoplastic polyvinyl chloride.
The colour aids visual inspection of the contents, an innovation followed by many. The manufacturer claims the 'Garrett Pan' is suitable for wet and DRY panning.
The wall slopes at 30-40 degrees, with 35 degrees being preferred. This is less steep than most contemporaries, perhaps in deference to the Kress hypothesis.
The generous space allows broad riffles on the slope, three riffles being preferred. The riffles extend for about a third of the circumference of the pan. This makes it a Janus pan, except when the inventor says the riffles can be complete rings. The riffles are sharp and the angle is 90 degrees. The inventor says that at 80-85 degrees "operation of the device is substantially impaired" but does not elaborate.
GOLD PAN patents from 1980 to 1990
Legg's Quick Miner's Pan (1981)
See-thru gold pan of vacuum-moulded thermoplastic.
The pan is transparent to permit ease of inspecting for gold. The inventor claims more throughput than a normal gold pan.
The pan is a typical circular gold pan, with the option of ring riffles on the flat floor. The centre of the floor is a trap, leading to a trough which exits the pan from below at 10-45 degrees; the inventor says 15-30 degrees achieve best results. The trough extends beyond the pan, and contains ladder-like steps that constitute riffles. The riffles trap heavy minerals in the trough.
The ladder of riffles is hinged for raising it clear of the trough base, so allowing rinse water from the pan to flush the heavies from the trough into a container.
In a variant, a trough is clipped to the rim of a pan, and periodically the contents of the pan pour down the trough where heavies are trapped by ladder-like riffles.
Morgan's Gold Mining Pan (1982)
A gold pan with an 'airlock' in the floor.
The inventor asserts that in a normal pan "gold settles in the first few swirls of slurry" and seeks to recover the gold immediately from below in a manner that eliminates the time and labour of panning away the lights.
The innovation consists of riffle like slots that trap the gold in the otherwise flat floor of the gold pan. Once accomplished, the panner then pulls a long lever that causes a shutter to shut off the slots and their content of gold in the 'airlock'. To retrieve the gold, the panner pulls a smaller lever sited beneath the pan that opens the base of the airlock allowing its contents to fall into either a bucket or an attached transparent inspection jar.
Ottrok's Method (1987)
A pan relying on toxic mercury.
The floor can be slightly concave or slightly convex, even a batea. The patent drawings are of a round gold pan with two half-ring riffles on its wall. This makes it a Janus pan. The side of the floor opposite the riffles is modified to be an amalgamation plate coated in silver plate. Copper is unsuitable as mercury tends to erode it. If the pan floor is metal, it is silver plated. If the floor is plastic a copper sheet is silver plated and attached to the floor by cyano-acrylic or epoxy adhesive.
A few drops of mercury are put on the silver and gently rubbed over the surface. The panner then pans material in the conventional manner. Very fine gold amalgamates with the mercury as a yellow film that coats the silver plate. The amalgam is scraped off with a plastic spatula and swept in a channel that conveys it to the edge of the pan where it is collected.
GOLD PAN patents from 1990 to 2000
Remais's Gold Pan with Classifier (1993)
A pan combined with a screen.
The device is made of tough moulded plastic and the pan and classifier are used connected or separately. The gold pan has a flat floor and its wall has incomplete annular riffles. The pan floor is circular but the pan rim is an elongate ellipse in common with the classifier. The screen (classifier) slots into the top of the pan, with a narrow space between to allow water to slosh out by tilting the device in any direction.
The elliptical shape bestows some advantages:
1: functions better as a scoop or catch basin;
2: the enhanced surface area facilitates collection of sediment dislodged from the side of a river bank;
3: when space is limited, the short end walls can be used; and
4: with or without the classifier, the gold pan can dig slurry.
Sediment is put of the classifier for removal of oversize; the fines drop into the pan where water is added and the pan swirled, hit, or otherwise agitated to disaggregate material.
Rosman's Gold Retrieving Pan (1997)
A pan for panning with or without water.
The pan is probably best made of plastic but differs from a conventional gold pan in the wall sloping inward at only 30 degrees, then curving rapidly to 90 degrees at the suture with the flat floor. This sudden curve acts as a circular riffle and causes the suture to be a circular trap for gold.
The most prominent innovation is the presence in the pan floor of a combination of "trap" and "trough", perhaps better termed riffle and dimple.
The gold pan is suitable for panning with or without water, and the panning method is rather different than with most other gold pans, as outlined below.
1: tilt the pan slightly north and shake about 30 times from side to side without spilling water;
2: tip the pan south and vibrate the pan while moving from side to side until all unwanted sand is opposite the trap;
3: scrape out the unwanted sand from the pan;
4: pour out the dirty water;
5: add half a pint of clean water, NOT directly over the trap;
6: tilt north and shake from side to side;
7: slowly flow the water over the trap and trough; then
8: reverse flow direction until any gold is visible and retrieve it.
1: add concentrate from a dry washer;
2: shake pan side-to-side 4 to 5 times, keeping the pan level;
3: tip the pan north and shake side to side 30-40 times;
4: tip the pan south and vibrate the pan while moving from side to side until all unwanted sand is opposite the trap;
5: blow lightly over sand near the trap to check for visible gold;
6: remove tailings by tipping the pan away from the trap; then
7: put the sand residue in a container for later retrieval.
GOLD PAN patents from 2001 to 2010
Kelava's Spiral Gold Pan (2003)
An innovative gold pan, economic if made in plastic.
The floor is set of spiral riffles arranged around a central cavity. The pan wall is very steep, more so than in other patented gold pans. The device seeks to maximise the trapping potential when the panner swirls the pan. As yet no tests have been published.
Lagal's Gold Pan and its influence today
Roy Lagal submitted his patent application in 1977 and it was awarded in 1979. The Garrett Pan, so branded by the manufacturer, became the market leader for North American gold pans, and is now entrenched as the norm of recreational miners, prospectors and western geologists. Garrett's and its network of distributors still proclaim it as "the world's only patented 90-degree riffle design that ensures rapid gold recovery in wet or dry conditions" albeit the patent is long expired. It has stood the test of time, and now the patent has expired it is freely copied by rival manufacturers. For instance the Keene SP-14 Super Pan is very similar.
Often the modern variants include small changes such as increasing the number of riffles, adding rough and smooth textured areas, adding a set of tiny riffles and so forth. For instance, Estwing produce a 350mm (14-inch) diameter extra heavy duty plastic gold pan with two riffle sections built in the wall, coarse Lagal-like riffles and fine "Chinese riffles and finger-grip rim". All are Janus pans.
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