One of of our customer from Australia told me that last week that they also buy vintage led bulbs from other suppliers in China, now they found some of the vintage led bulb burnt after several hours lighting on, and they found there is a lot of moisture inside the glass stem tube after the vintage led bulb is burnt. They tried to contact the supplier, but not get replied for one week, so they asked me about this issue, because we have been cooperating with each other for more than 6 years.
My customer sent the pictures of the burnt Vintage style led bulb and moisture glass stem to me, I transferred these pictures to our QC, our QC replied as below:
1. Each of the vintage led bulb we produced has to be vacuumed firstly from the glass stem, the glass stem has a glass tube at the top part, the vacuum is done through this glass tube on the gass stem. After vacuuming to vintage led bulb is finished, we inflate helium gases inside the vintage led bulb from the same glass tube on the glass stem, we will seal this glass tube after finishing inflating helium gases.
2. Both vacuume and helium gases inflation wil be tested, we have a testing machine and testing standard, all the defects will be pick out.
3. Why we change the normal air inside the vintage Led bulb by Helium? because there is a lot of moisture and dust in the normal air, these will be heated and adhesive to the glass of the vintage led bulb, then the vintage led bulb will looks much dirty, seems like there is moisture inside the vintage led bulbs. As well, the helium is a much good of heat sinking material, the helium will be heated and move in a circle way inside the vintage led bulbs, helium takes the heating to glass, the heating will be transmitted to outside of the vintage led bulb.
4. However, if there is some broken on the glass stem, then helium will leak out and normal air will go into the vintage led bulb, the normal air will be headted and change to moisture, and after some time lighting on, the vintage led bulb will be burnt.