Introduction
This article looks at whether LED light bulbs are made out of glass.
I had a look at the light bulbs in my house. Certainly the frosted ones could be glass. Equally they could be plastic. It is hard to tell without dropping them or hitting them with a hammer.
So it seemed interesting to find out the material they are. After all I have been buying light bulbs for years. How come I don’t what what is in them?
A quick search on the internet was not very revealing so I decided on further investigation.
Before I get into my results a little history on early light bulbs.
Why early light bulbs were made out of glass
When Edison started working on his light bulb back in 1879 the material of choice was glass. That is because glass was strong, heat resistant and relatively easy to work with.
Early light bulbs were hand blown. With the screw attached at the bottom of the light bulb. In order to extend the filament life the bulbs contained a vacuum. For this reason the bulb maker removed air from the top of the bulb using a pump. Afterwards they sealed up the small hole.
Very soon after the production of light bulbs became automated. The first light bulb factory opened in Benwell in Newcastle, England in 1883. It was set-up by Joseph Swan, a rival of Edison. Factories in the United States followed very soon after.
These early factories continued to use glass. It was cheap and readily available. Also, glass products were already being mass produced. So the technology and know-how was already present.
A very brief history of LED light bulbs
LED light bulbs seem like a relatively new invention. However the technology they use is almost as old as the incandescent light bulb.
LED light bulbs contain a number of light emitting diodes (LEDs). Like a filament, they give off light when a current passes through them.
See our article on how a LED light bulb works for more details.
The process whereby LEDs give out light is called electroluminescence. In 1907, a scientist called Henry Joseph Round noticed the phenomena. He was experimenting with Silicon Carbine. When a current passed through it he saw that it gave off a low yellow light.
Nick Holonyak, Jr. invented the first LED that could produce visible red light. It was 1962 and he was working at General Electric.
In 1994, Shuji Nakamura a Japanese scientist, invented the first ultra-bright blue LED. And soon after an ultra-bright green one too.
Red, green and blue LEDs combined, producing white light.
Thus the technology producing cost-efficient and functional light with LEDs was now available.
Components of an LED light bulbs
Within a LED light bulb there are several components:
- LED Chips. These are the pieces of semiconductor that produce the light.
- A lens that focuses the light.
- A heat sink that takes heat away from the LED.
- A circuit driver which turns on and controls the LED chips
- The housing, which is the bulb itself
- The base, with its screw connector
So, our question about LED light bulbs being made out of glass actually refers to the housing. Namely, the external bulb part.
Benefits of Plastic vs Glass
We saw why early light bulbs use glass. Indeed glass has a lot of positive properties. On the other hand so does plastic.
So, here are some reasons for using the two materials
Glass: Positives and Negatives
Positives
- Cheap and readily available
- Very high level of light transmission
- High melting point
- You can make it into whatever shape required
- Tends not to discolor with age
Negatives
- Is fragile. A particular problem as most light bulbs come all the way from China.
Plastic: Positives and Negatives
Positives
- Cheap and readily available. In fact slightly cheaper then glass.
- Lighter than glass
- Much tougher and harder to break than glass
- Easily shaped. You can injection mold it.
Negatives
- Has a tendency to discolor with time
Overall
As shown above, plastic is cheaper than glass and is lighter. Also it is significantly stronger. On the other hand it can discolor over time. A problem in bulbs that may last 20 years.
What do the major brands make their light bulbs from?
So, now that we know the benefits of glass and plastic, lets look at what major brands make their light bulbs from.
I looked at the major brands available here in the United States.
General Electric
Not only have GE been in business since 1892 they are also the most popular brand here in the U.S.
I checked out their major ranges with the following results.
Glass – GE Relax, GE Classic, GE Refresh, GE Vintage
Plastic – GE Reveal
Sylvania
After GE, Sylvania is the next most popular brand of light bulbs in the U.S.
All of the Sylvania ranges use plastic bulbs. This included Sylvania, Sylvania ECO and Sylvania Daylight
Feit
Feit are a family owned and operated company based in Los Angeles, California. According to their website they keep a stock of over 100,000,000 bulbs. So as to reduce order waiting time.
Their standard bulbs are plastic. While their vintage bulbs are glass.
Feit actually make a range called “Classic Glass Design”. As the name suggests the bulbs are glass.
Philips
Philips are an interesting example.
In December 2017 Philips release the Hue 3.1. It differed from the 3.0 in that the diffuser changed from glass to plastic. Apart from being lighter the bulbs were identical.
The diffuser is the top part of a two-part light bulbs.
Currently the diffuser on the Philips Hue is made of PMMA (Polymethyl methacrylate). PMMA is known as acrylic glass and is the same material used in airplane windscreens.
Recycling of LED bulbs
Both plastic and glass are materials that are recyclable.
However LED bulbs contain small electrical components. As such LED light bulbs need to be taken to a specialist recycling point. The good news is that there are lots of them. For example big-box stores like Lowes, Home Depot, and IKEA may offer in-store recycling bins . For more details see this article from earth911.
Final Words
Hopefully I have shown whether LED light bulbs are made of glass.
Like a lot of questions the answer is yes and no. Some are, and some are not.
If you are looking for a light weight bulb. Or you need one that will not shatter. Then consider buying a plastic bulb.
However, if you want a statement, classic or vintage bulb then you might want to stick with glass.
Checking if that LED light bulb is made from glass?
As I found out writing this article, manufacturers are not very good at telling you what they make their products out of.
The best resource I found was Amazon. They sell a huge range of light bulbs. Normally, on the right of a product there is a “See more product details” link. When you click on this you go to a technical details table. This table lists the material. In the case of light bulbs this is normally glass or plastic.