The other side shows where the ink stopped seeping under the silicone:
I don’t know if I melted the side of the LED or if it came that way, but, oddly, there’s no leakage on that side.
This LED matches the layout of Josh’s “crappy” LEDs, as does the entire lot below, although I suspect that’s more coincidence than anything else; there aren’t that many different layouts around.
Flushed with success, so to speak, I ran the Sharpie around all the unused LEDs from that order:
I tested the process on the three LEDs in front, then wiped the ink off with denatured alcohol.
A closer look shows the ink all around the silicone-to-case border, with plenty of opportunity to seep in:
After wiping the ink off, none of the 31 unused LEDs showed any sign of poor sealing.
I haven’t been keeping good records of the failures, but right now I have twelve functional WS2812 LEDs attached to various glass doodads. That leaves 7-ish failed LEDs out of the 15-ish with long term use (not counting four recent replacements).
In round numbers, that’s a 50% failure rate…
I should wire up the remaining sheet of LEDs as a test fixture, let them cook for a while, and see what happens.