[PSUBS-MAILIST] Emer Buoy brake and clear resin

[Jon Wallace via Personal_Submersibles]

 Sean, I don't have an IR thermometer but will pick one up and do some measurements. It never got too hot to hold continuously with my bare hand even after 30 minutes so it had to be less than 44C. In water it should be no issue at all.

I saw your message regarding 832WC but it was expensive and since there was a lot of concern that the LED's would burn out rather quickly, I used a cheap "craft" resin to cut my losses in the event that happened. I have no specs for the craft epoxy other than it's got a Duro of 85 when hardened and is supposed to have UV protection. I do have some concern that this epoxy may soften where it is in direct contact with the individual LED diodes but time will tell if that happens. Now that the concept is proven (with certain lights) I agree 832WC is a superior product and would be appropriate for future builds.

Jon
     On Friday, February 21, 2025 at 08:08:39 PM EST, Sean T. Stevenson via Personal_Submersibles <personal_submersibles at psubs.org> wrote:  
 
 Jon - I wonder if you have any way of measuring the in-service temperature of the operating LED when potted (IR thermometer)?  Does the resin you are using have a temperature specification?
For reference, the MG Chemicals 832WC (water clear epoxy potting and encapsulating compound) product that I suggested earlier indicates the following:
"This product is designed for applications where high clarity is required. It does not yellow when exposed to UV light; it maintains clarity in applications with service temperatures of up to 65 °C (149 °F) and intermittent exposures of up to 100 °C (212 °F). It can be used for underwater applications such as swimming pool light potting compound. It is also a good choice for casting resin.
This casting epoxy also provides excellent electrical insulation and protects circuit boards and other electronic devices from static discharge, vibration, abrasion, thermal shock, environmental humidity, salt water, fungus, and many harsh chemicals."
...which seems to suggest that if a potted assembly can keep under 65°C / 149°F while submerged, there should be no issue with breakdown of the epoxy (for that particular epoxy).
Are you able even to ballpark how hot it was getting? The threshold for too hot to handle continuously with a bare hand is about 44°C / 111°F, so 65°C is warmer than you think.
Sean
 On Friday, February 21st, 2025 at 17:43, Jon Wallace via Personal_Submersibles <personal_submersibles at psubs.org> wrote:
 
  Just finished testing a second LED light which I filled with epoxy only enough to cover the diodes and other electronics. My light meter shows a 10% output increase over the fully filled unit, however to my eye the two appear almost exactly the same. Both units utilize the reflectors that came with them.

Here's the link again to the brand/model I have tested.
https://tigerlights.com/products/50w-compact-led-flood-light-generation-2-tl500f/

Jon  

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