I've noticed most GU5.3 light bulbs, both halogen and LED, contain a granular material at the base.

There seems to be considerable variation in how much of this powder is present, even within the same brand and type of lamp. Sometimes, the base is filled with the powder. Sometimes there are large gaps or empty spaces with only a small quantity of the powder near the connectors.

A small amount usually extrudes through the holes where the pins pass through casing, and I occasionally note slight discoloration on some pins where this occurs more than usual.

enter image description here

What could this powder be? Could it be cement, perhaps, or for heat dissipation?

Is there a higher failure rate with those bulbs that have less of this powder?

  • \$\begingroup\$ are you sure that it is a powder? ... the ones i have seen were all solid \$\endgroup\$
    – jsotola
    Oct 5, 2019 at 2:28
  • \$\begingroup\$ It looks granular in appearance, as in the image, which is what I meant by 'powder'. There seems to be an adhesive or substrate of some kind holding it together, which would make it solid as well. \$\endgroup\$
    – Brybeck
    Oct 5, 2019 at 5:04
  • \$\begingroup\$ it;s some sort of ceramic (ceramic is basically powder glued together by melted stuff) if I had some more detail I'd post an answer. \$\endgroup\$ Oct 5, 2019 at 7:02


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