A few weeks ago I was discussing a minor problem with one of the Caffin stoves with Roger Caffin, the manufacturer and Editor for Backpacking Light. His stoves are custom produced in his workshop in Australia. He wrote a series of articles explaining his design process and finalizing the design he is currently offering, starting at The Evolution of a Winter Stove, Roger Caffin, BPL, 5 parts starting in July 2013.
I mentioned that after some use I found there were a few metal flakes on the O-ring inside the canister shut-off valve which is part of his stoves, and that I had gotten into the habit of wiping the Lindal valve off before use. I had tested this roughly with a bandana and a drop of olive oil on five canisters from various manufacturers and then by wiping the oil on a piece of paper. He replied that this was new information and requested a picture.
Of course, I had simply tossed the paper and washed the bandana. So, the test was repeated, despite the fact that the canisters were already cleaned. I was assuming (yes, I know how to spell it) that there might be some residue left on the threads, and I could use some clean white paper towels for the pictures. A new test was done under these conditions and a few low-resolution pictures were taken. I e-mailed these to him and he agreed that there was something to this. Here is the first picture which formed the original concept for this article:
This was the first picture documenting a problem with dirt, stains and debris coming from gas canisters with Lindal valves.
I reluctantly agreed to write it up for BPL. So, here is a brief hypothesis of what I *think* is happening. Most of the dirt and metal particles from the canisters are from the manufacturing of the Lindal B188 Valves. All of the debris is fine enough to get into any canister stove, just more so with liquid-fueled or inverted canister stoves, where the liquid fuel can wash the debris along.