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Shaving Cream Makes Low-Cost Spray Marker
Shaving cream and spare parts from your farm shop are all you'll need to build a do-it-yourself "Poor Man's" spot spray marker for less than $3.
Developed by Truman Massee and Harold Waggoner at the USDA Snake River Conservation Research Center in Kimberly, Idaho, the marker uses shaving cream to spot mark the sprayer's return pass.
"Depending on boom length, a can should last for 8 to 10 acres, applying a blob of foam every 30 to 50 ft. We tested four different brands and they all performed equally well," explains Massee. "Under normal conditions, the foam will last up to 3 days before dissipating. One drawback is that in strong winds, the foam blobs may blow farther than the spray."
To make the marker, you start with a 7 1/2 in. long piece of 3-in. dia. PVC pipe which holds the shaving cream can and forms the main body of the marker.
Next comes the tricky part making the trigger which presses down on the shaving cream can button. Cut out a 3-in. wide, 4-in. long section from another piece of 3 in. dia. plastic pipe, and fashion it into a "T" shape. The firing pin, or top of the "T", should be about 1/4 in. long (see photo).
The trigger sits inside the 3 in. pipe and is held in place by a nail that goes through the arms of the "T" and the pipe. The trigger arms should be beveled slightly to fit against the inside of the pipe.
It's important to have the firing pin centered over the top of the spray can but to have the nail, the trigger's pivot point, slightly off center so, when the trigger is pulled, the firing pin presses down on the button.
After fitting the trigger, place the shaving cream can in the pipe and drill a hole for a nail or bolt to fit through on the bottom of the pipe. This supports the can at the proper height to make contact with the firing pin.
Massee drilled a small hole through the nail and inserted a safety pin to hold the nail in place. He points out that this lets you replace the empty cans quickly. He also put cardboard shims in the pipe to keep the can centered.
Next, cut a 3/8 in. wide, 1 1/2 in. deep, notch in the top of the pipe to make room for a 3/16 in. dia. plastic tube extension that connects to the can's nozzle. The tubing can be cut to any length, as long as it gets the foam out of the marker. On windy days you may want to use longer tubing.
To increase the blob size of the foam you can split the clear tubing at the end and insert a small funnel.
Massee explains that, since spray can caps remove easily, you can glue the tubing on one nozzle and cap and then use the same cap for all the cans.
The next step is to run a rope from the top of the trigger to the tractor. When you want a blob of foam, just pull the rope.
The marker attaches to the spray boom with a hose clamp that inserts through 2 slits cut in the backside of the PVC. A short piece of scrap plastic pipe cemented to the pipe between the boom and the marker helps absorb the stress of the bouncing boom.
For more information, contact: FARM SHOW Followup, Truman Massee, Snake River Conservation Research Center, Rt. 1, Box 186, Kimberly, Idaho 83341 (ph 208 423-5582).

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1983 - Volume #7, Issue #3