Our trip to Walmart in preparation for a camping trip found the following camping utility in our basket -- a neat battery operated lantern for less than $6.00!   What a deal, however, one often gets what they pay for.   In this case, we got much more glare than we had expected, and as a result, we would have turned into another fun-loving but unknowingly obnoxious camper obliterating the enjoyment of the peaceful night for someone else beside us.

A stiff chrome plated wire loom fits into the plastic pilaster where the bulb is mounted and extends up into a loop that allows hanging and also holds the shade in place.   The shade distributes some of the glare to a larger surface area, however, in dark surroundings this light still causes enormous uplighting and light trespass that extends negative impacts over great distances.   The illumination under the lamp left a lot to be desired as indicated in the photo below.

Notice how a veil of luminance obscures the lantern and the surface below due to the high contrast being created by the shade.   Imagine the impact a lantern like this has on adjactent campers 100 feet away!   From a distance this fixture looks like a construction light on the side of a highway!   Clearly, something better had to be developed.

The wire loom holding the plastic shade is slightly smaller in cross-section than a tomato paste can diameter. These little cans were used to create the first battery operated full cutoff camping lanterns and the results were truly amazing!

Careful measurements were made to determine whether the can would suit the intended purpose. It was the perfect size in every direction, including its diameter.  Two holes were punched and reamed to the size of the wire and a putty knife easily cut a slit between the two holes. A bit of pressure forced the loop of wire loom through the slit in the top of the can and it rested perfectly about 1/2 inch below the bulb.  The plastic shade was refitted and covered the can entirely, so when turned off the lamp looks identical to the photo at the top of the page.

When the switch is turned on a completely different lighting effect enabled much better visual conditions.   The surface below and directly adjacent to the lamp improved ten fold in quality and the cutoff angle meets the IESNA 80 degree specification.  Illuminance measured above the 80 degree line dropped off to zero on the 1/100 footcandle scale of the light meter as the sensor approached the horizontal plane.   An FCO camping lantern has indeed been achieved, all thanks to 4 ounce tomato paste cans and a bit of imagination!

Taming the Gas Coleman Lantern

A common element at nearly every campsite is the enormously bright gas powered lantern. Retardless of where you go someone has one searing into everyone's eyes and lighting up the trees as well as trespassing into other campers' nearby space. There is hope for taming this beast, however.

To make shields for the typical gas mantle lantern with a straight cylindrical glass lens the most durable material is aluminum roof flashing available in 8" wide rolls from any reasonably well stocked hardware store. Usually a 50 yard roll costs less than $10, but you can shield many outdoor lights of different kinds with what is left, PLUS repair your roof someday so it is well worth the investment. This flashing also works quite well for making griddle cakes for breakfast on a Coleman grille or gas stove. Nothing like a stack of hotcakes on those crisp dewy mornings!

A good pair of tinsnips is an invaluable tool for any well equipped camper, and this shielding materal cuts like a hot knife through butter when you have the proper tools. All hardware stores sell tinsnips and they are reasonably priced. We never go camping without a pair of them in the trunk for emergencies. A heavy duty pair of scissors will also suffice, but they will get dull and may get nicks when cutting metal. Tinsnips will not get dull when cutting metal because their jaws are hardened and they are well worth the investment.

Click on the image below and review the concept of how this lantern shield works and where its relationship to the bottom of the gas mantels must be located for it to shield the glare and reflect useful light downward and outward effectively. Print this diagram for future reference.

Here is how the gas lantern shield is created. Refer to the diagram above as needed.

1. Remove the top shade that holds the lens in place. Usually there is a knurled round nut or screw in the center of the top of the shade. Remove it (remember: 'righty tighty, lefty loosy') and carefully lift the upper visor and handle assembly from the lantern body. Place the nut in a cup or somewhere it will be easy to find for later assembly.
   
2. Measure how deep the bottom of the mantles extend into the glass lens and mark the glass with a fiber tip pen for future reference.
   
3. Carefully remove the glass lens from the body of the lantern and unroll enough flashing to completely encircle the lens plus around 1/2" for good measure. You can trim away the excess if needed later.
   
4. Use your fiber tip pen (a well pointed Sharpie works great!) to mark where to cut the flashing. Extend the line across the whole sheet.
   
5. Remove the glass lens and place it aside in a safe place where it will not get knocked over.
   
6. Carefully cut the piece of flashing you wrapped around the lens along the line.
   
7. Flatten the flashing on a smooth surface and place the glass lens onto the sheet of metal so the reference mark for the bottom of the mantles is roughly 1/8" higher than the long edge of the sheet. Use your Sharpie to mark the sheet using the top of the glass lens as a guide. This mark will serve as a 'bend line' reference when assembling the shield.
   
8. Move the glass lens up another 1/2" beyond the last marks on the sheet. Your lower reference mark on the lens indicating where the mantles are when assembled should now have roughly 5/8" of metal sheet extending beyond that mark on the opposite end of the lens. Draw a line on the sheet using the top end of the lens for a guide and extend that line across the whole length of the sheet. This is the cut line. Use a ruler if possible, but if one is not available, rolling the lens in a parallel direction works well if you are careful.
   
9. Carefully cut the shield along the top cut line. Be careful and take your time because the edges of the metal will usually be sharp.
   
10. Cutting the metal along its length may cause minor distortion to occur so carefully flatten it out on a smooth surface again. Using the bend line as a reference, take your marker and draw a line across the longest dimension of the shield. This is the bend line but it also serves as a reference line when cutting tabs that will bend over the glass lens to hold the shield in place. This line should be no greater than 1/2" from the top edge of the shield that was just cut.
    
11. Carefully roll the sheet so it is diameter is roughly 1/2" smaller than the interior diameter of the glass lens and place it inside of the lens. The memory in the flat sheet will cause it to spring open and expand to the diameter of the lens. Take your Sharpie and place a mark where the metal overlaps itself at the top and bottom of the sheet.
    
12. Remove the curled sheet from the glass lens and draw a line between the two overlap reference lines, then carefully cut along that line. Roll the sheet up again and place it inside of the lens. It should now have a snug fit without an overlap or open gaps where the two edges of the sheet meet. If there are gaps you may be able to use the scrap from the first longitudinal cutting to make another shield. Cut more carefully when repeating this step next time. Don't feel bad, we do not all get it right on the first try and if you goof up its cost you less than ten cents, so no big deal.
    
13. Once you have established a good tight fit for the shield on the inside surface of the glass lens carefully remove it, again placing the lens in a safe spot so it does not get damaged. With your tinsnips carefully cut 1/2" wide tabs along the top perimeter of the metal sheet by cutting straight down from the top edge to the bend line. Continue cutting 1/2" wide tabs along the top perimeter of the sheet until you reach the other end.
    
14. Carefully roll the sheet and place it into the glass lens again so the top edge of the lens meets with the bend line and carefully bend the tab opposite of the two mating edges of the sheet outward and over the glass lens. The next two tabs to bend outward over the outer edge of the glass lens are the two mating surfaces. Bend one tab in the middle between each of the two halves over the outside edge of the glass lens. You should now have 5 tabs bent over the outside of the glass lens. Check to assure the metal sheet is parallel with the bottom of the lens about 1/8" below the reference mark that represents the bottom of the mantles. If it is not parallel adjust it as necessary using adjacent tabs to the ones you have already bent over and straighten out the tabs that were incorrectly bent.
    
15. Carefully remove the rolled sheet from the glass lens and now trim away all of the unbent tabs from the top edge using the bend line as a guide. When all of the unbent tabs are removed carefully roll the sheet up again and fit it inside of the lens.
    
16. It's time for the 'acid test' so assemble the lantern carefully and briefly try out the new shield. Some last minute adjustments may be needed, so do not panic. Work slowly and carefully when making any final adjustments. Be sure to let the shield cool off for a few minutes after extinguishing the lanten because the metal can get very hot quite rapidly.