Does it make sense to use Teflon tape on threads, at least those that stay shut nearly permanently, to make the light even more waterproof?
Sure, teflon type is made for that purpose.
But do people do that with flashlights? I couldn’t find any references to it, so it may be either a novel idea or there is some reason not to? Maybe the silicone grease and the Teflon tape don’t like each other that much? Or maybe I don’t know how to look and this is what everybody is doing? Or maybe this is totally extraneous?
Teflon tape is used on pipes that have pressurized water in them.
I dont think you will ever have pressurized water inside or outside of a flashlight.
The only exception is if you use a diving light for diving. Even in that case you would probably be interfering with the o ring and you will make the situation worse.
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Certainly not on the ring(s) - just threads. Also, I’m pretty sure that the direction of water trying negotiate the threads is not that important i.e. it doesn’t have to be from inside out.
One motivation for the idea is that a flashlight may have 3 threads - say bezel and both sides of the tube. I want only one of them to work regularly to change batteries. So maybe applying the tape to the other two (sans o-rings) could serve as an extra semi-permanence?
It wears out every time you unscrew tailcap etc. So maybe when you have USB charging it make sense. But all decent flashlights have good IP rating, so you don’t have to take care of it.
USB charging port is likely the biggest weakness for water ingress.
For non-rechargable lights, I’d assume if a light were to “leak” the most probable point would be the bezel threads or between the glass and the bezel- head/tailcap threads protected by an O-Ring should be well protected.
Not sure it’s physically possible to wrap Teflon around the typically very narrow bezel, and you’d still have the issue of water getting in between the bezel and the glass, which my guess would be the weakest point.
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New tape would be needed with every cell swap. Also, PTFE is a tremendous insulator so if the threaded connection is designed as a conductive one and/ or if some tape gets wedged between two contact faces, no more light.
Correct, Teflon tape is a one time use item.
Also correct, you would have to get it perfectly between the o ring the tube end being real careful not to come close to either.
You’re over-thinking, it’s fine as it is.
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I use Teflon tape on twisty key chain lights to prevent the head from working off. It adds just enough resistance to make it stay put.
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Have not thought about this…
But you have to admit it’s an idea, just not necessarily a good one…
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I use one layer of Poly-Temp XHD (extra heavy-duty) PTFE tape on my flashlight threads. This tape is much thicker than typical PTFE tapes, so a single turn is sufficient for my needs. If you use more than one layer, you might have difficulty screwing the threads together.
I use the tape to make the threads smoother and cleaner, serving as an alternative to thread lubricant. My primary goal is not to waterproof the flashlight; I believe o-rings are responsible for that. While you could use PTFE tape for waterproofing by tightly sealing the threads, it would require replacing the tape each time you unscrew the threads.
There are two main advantages of using PTFE tape over lubricant. First, it provides smoother action than any lubricant. Second, unlike lubricants that can attract dirt and get dirty due to galling of the threads over time, PTFE tape remains clean as long as the tape is not ripped.
However, one major downside is that the tape can tear. Several factors contribute to this tearing, with the most significant being sharp edges and spring tension. If the threads are anodized and smooth without sharp edges, one application can last through multiple screws and unscrews. In my experience, not all threads are smooth and free of sharp edges. In some cases, I had to use high-grit sandpaper to smooth out these sharp edges. This sanding process is not enjoyable, and it is difficult to tell if it is done correctly. Therefore, in such cases, it might be better to use thread lubricant instead. Additionally, if there is enough spring tension that you have to apply force to align the threads for the first turn, it is likely that the tape will tear.
Lastly, you cannot use the tape where electrical conductivity through the threads is required, which is the case for many bare threads.
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No, it doesn’t make sense lol
Pipe threads, where teflon tape is used to help make joints water and gas tight, are special. They are cut with a taper. When tightened the threads jam together and the tape helps to make the seal. When or if the coupling is unthreaded the teflon material must be replaced.
On flashlight threads I would place .much more faith in an o-ring that is the correct size and lubricated.
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But if you use Teflon tape it stops the battery negative connection.
This kind of feels like one of those things where there really isn’t a problem that needs fixing.
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I promise not to do that again :-)
But now I know.