I’ll put down a few words on the subject, and hopefully it will make sense.

Picking up a shovel and just throwing some dirt on the hopper is the way everyone starts. After a few years and a lot of hard learned lessons, the finesse of the whole thing starts to become a little more clear. I like to think of Drywashing as a form of art rather than science. That’s because there are so many variables that go into it that a person almost has to become one with the operation before everything flows just right.

Lets start with the dryness of the soil. That’s the main variable to consider when Drywashing. The way I test it is to take a handful of soft dirt and squeeze it in your fist. When you open your hand the dirt should crumble away in fine grains, not clumps. If it’s clumpy or stays in a lump there is moisture in it that will have to be considered. That doesn’t necessarily mean that it’s too moist to work. That’s a judgment call based upon several factors. If there is moisture, my preferred procedure is to dry it in the sun on a sheet of plastic. Sometimes I’ll run it anyway if I’m using the 151 and I think that a couple of runs through will dry it because the 151 blows hot air from around the muffler and will hasten the drying process. Sometimes you can actually see the dirt dry out as it passed down the riffle try and gets hit by the hot air off the engine. It will start at the top of the tray as a dark brown and turn to a light brown as it goes off the end. The best method is to crevice, snipe, screen and get a smaller quantity of material. Take it home in buckets and dry it rather than stand and try to work damp dirt in the field.

Now let’s assume you’ve got dry (gold bearing) dirt to work with. Maybe that’s too big of an assumption. Let me back up. Don’t set up your Drywasher before you’ve tested and made sure there is gold in the dirt you want to work. There are two main methods of testing for fine gold in dry dirt. One is the dry panning method. I have to admit that I’m not a pro at that. I bought the pan and video that Phil (NM) put out and I’m working on it. I think after I have it down, it may be the best method. Up until now I’ve just used a small test bellows type of DW. Five minutes in an area will usually tell me if it’s worth pursuing.

The next variable to consider is screening. Remember the old saying “all recovery starts with classification”. I cut a piece of 1/8” brass screen (a fraction over size) and just wedged it into the hopper on top of the original classifier. I’ve done this on most of my Drywashers. It is still removable and I’ll discuss that in a minute. This does two things. First of course it reduces the size of the rocks allowed to go into the riffle tray. A 1/4” rock in your first riffle will displace a whole bunch of smaller specks of gold because it’s heavier than each of them individually. I only remove the screen if I start seeing course gold in the cleanup. The second thing this does is to allow for constant and easy feeding of the material through the flow gate of your hopper. Nothing is more bothersome than having to stop every minute and stick your finger up the flow gate to unstop a clog. Steady flow also increases the recovery rate of the operation as compared to stops and starts. Here I’d like to say that a variable is just that - it varies!! So, if I say something that sounds like a good idea to you - remember it doesn’t always work. There are exceptions to everything; that’s why I call Drywashing an art form. Let me give you an example. Last year at the Roadrunner assessment dig we had Drywashing teams; each team had a 151, and we were lined up 25 yards apart in the middle of the same creek. Each team had a pile of dirt taken out of the center of the stream by a backhoe. My team was working with the 1/8’ screen in the hopper. I knew we weren’t getting much gold, but that was the program for the day so we just kept working. The team next to us were just shoveling like crazy directly onto their hopper with no prescreening. Their flow gate was wide open and the material was running several inches deep over their riffles. At the end of the day they had recovered 3 or 4 times the gold we had. I believe that their success was a direct result of processing 3 or 4 times the amount of dirt. The lesson here is that if you are in a coarse gold area, throw caution to the wind, move as much material as you can, and let your Drywasher work !!!

The next variable to mention is air volume/speed. There are two ways of controlling the air volume. First is engine RPM. and second is riffle try netting. I said earlier that you should be able to “catch down to 200 mesh”. I didn’t mean that you would catch every 200 mesh speck that goes over your try. But a well set up DW should have no trouble catching a “good percent” of that size gold. The trick here is to watch the dust that is produced when the material hits the tray. You want to blow the dust off and keep the heavies. Some boxes will have an uneven air flow. That is some riffles in the tray will blow out too much, others not enough. The best operation of the 151 will have “blowing” in the first riffle and a “boiling” action in the rest. On my 140 I had to add a sheet of nylon sunscreen netting under the original material because the air volume from the preset speed on the Vas Pac motor was too high. An uneven action was the result. To explain why you should use nylon, I’d like to quote a paragraph from Dry Washing For Gold, by James Klein.

“..Gold is non-magnetic, but it does have an affinity for an electrical charge. The Keene Electrostatic Concentrator uses a high-static air fan to force (hot) air into the Marlex plastic base, where it gets a charge from the plastic. From there the air moves under pressure through a special cloth under the riffles, which creates an even greater charge. This electrostatic charge in turn passes on to the gold particles, causing them to be attracted to the cloth and stick to it.....perhaps you haven’t heard what happens when a blast of air is forced through a nylon screen in contact with cotton cloth. This combination sets up a charge of static electricity in the cloth which acts like a magnet to hold the fine gold. Under a magnifying glass, these fine gold particles can be observed actually standing on end as they cling to the cloth above the riffle.”

This is good news however, I would like to add that this “electrostatic grip” can be overcome by too much air pressure and your fine gold can be blown out.

Gravity is a variable and another force at work here. So, let’s discuss the angle of your dangle (grin). Actually we need to discuss the feed rate, flow rate, and angle of the box altogether here. These three variables will determine how fast the material will be processed. This is not crucial during testing with a puffer, but it is very important after you set up your production run. The feed rate is simple. How fast can you shovel? You want to have enough material in the hopper at all times so that a constant flow will be going through the gate. If you are using a 1/8” screen (or maybe even a 3/16th” screen), there should not be a problem with clogs. The best approach on the 151 is to set the flow gate and the angle of the riffle box so that there is a good “boiling action” in each riffle and that the DW will process each shovel full of material by the time you’ve added another one. Let me say here that I believe a 151 is best suited for a one man operation (providing that man knows how to work). To have two men feeding a 151, the material would have to be bone dry and well classified and set at a steeper than recommended angle. [Exception] Sometimes the added volume of material processed will more than make up for the small amount of gold lost by running too fast. It’s another judgment call.

The last variable I can think of off the top of my head is vibration. With a bellows type DW, the clunking up and down provides a good settling vibration. With most blower type units the vibration is caused by an off set weight attached to the fan under the riffle tray. Most people who own DWs have never adjusted these weights, but just use the factory setting. Two points here. First, it may be interesting to note that faster vibration will help to settle gold if you are processing slightly damp material. Point two, too rough a vibration in combination with too much air pressure is disaster. It will pop gold right out of your box.

I just want to add a word about prospecting with a Drywasher. For testing a new area you can’t beat some of the smaller wooden bellows units that are on the market. Some even collapse for backpacking. Don’t be afraid of them because they were “home built” or found at a yard sale for $5. Sometimes only small modifications are necessary to make one into a really good test unit. For production work I like the Keene 151. The hot air feature is a big advantage in slightly moist soil. However, for a true “back in time” experience, everyone should try a hand crank bellows Drywasher at least once. If you are working an area where you can’t shovel large volumes of material, they are a really good choice. Such areas would include: Bedrock areas where crevicing, sweeping, and even hammer and chisel work is necessary; also cemented gravels that require a pick or digging bar may only give you a small amount of high grade material. In such areas it may take 15 minutes to fill the hopper of your Drywasher, and only a few minutes to run it through with the crank handle. No need for a motor there. The “clap-ity/clap” of the bellows as you search for your golden reward in a remote desert location is a loving sound to the heart of every Drywashing prospector.

.......russ ford