You can’t cheat physics.
Why doesn’t every light bulb do the job?

 

Why using one light bulb provides us with beautiful, clear light patterns while another one gives us only blurred spots?

Which light bulbs are the best for gourd lamps and why?

The main rule we have to keep in mind is that each hole in the gourd maps its light source.

This is clearly visible in case of the filament light bulbs where the filament is “C” shaped. Each light point projected onto the wall is similar to this shape (it is also its mirror image).

So, the smaller the light source, close to the single point, the better, because we want each hole to project one, the clearest possible light point on the wall.

This is clearly seen in the pictures below.

Photo 1 – LED Diall, 180lm, 1.8W
If the light source is too big (e.g. a large milk bulb or larger LED bulb like this), the light points will be blurred and will overlap. Everything will be blurry.

Photo 2 – LED Diall, 200lm, 1.8W
Photo 3 – Philips CorePro LED Capsule, 2W, 200lm
The light source consists of 4 LEDs (2 on each side). Therefore, each hole casts two points of light and the patterns are also not very pretty.

Photo 4 – Halogen OSRAM, 20W
The halogen filament is small enough (about 4 mm) to cast light very well through each hole.

Photo 5 – Philips CorePro LED Capsule, 1.2 W, 120 lm
A very small (about 3 mm), round and single light point (one diode on each side) gives the clearest light patterns.

As we see, in terms of light patterns, the best bulbs for gourd lamps are halogen bulbs or Philips CorePro LED 1.2 W. Each of them, however, has its pros and cons.

HALOGEN
vs
Philips CorePro LED

 

DISTORTION OF LIGHT AT THE TOP

Halogen – The light at the top of the bulb is distorted, making the light patterns, cast through the holes at the top of the lamp, less clear and visible. This can be seen in the photo of my Nepenthis lamp.

LED – The top of the bulb casts a very clear light, so the light patterns cast from the top of the lamp are very sharp.

DISTORTION OF LIGHT ON THE SIDE

Halogen – No distortion of the light patterns on the sides.

LED – Because this bulb consists of two diodes on each side, the light patterns in two areas are less visible. This can be seen in the photo of my Ailsa lamp.

HEAT GENERATED

Halogen – The high temperature of the bulb generates quite a lot of heat, but it is not dangerous in any way and there is no risk of the gourd catching fire. The gourd is just a little bit warm.

LED – Very low bulb temperature.

LIGHT BEAM ANGLE

Halogen – Larger light beam angle. Smaller shadow zone at the bottom.

LED – Smaller beam angle and larger shadow zone at the bottom of the bulb.

LUMINOUS FLUX / LIGHT TEMPERATURE

Halogen – 335 lumens. Bulbs give more light. The carvings are brighter and look better. Light temperature 2800K.

LED – 120 lumens. It might seem that this bulb should give almost three times less light than halogen, but in fact the difference is not that big. However, it is slightly darker than halogen and the carvings are not that bright (but still look good). Light temperature 2700K.

LIGHT BULB LIFE TIME

Halogen – 2.000 h / LED – 15.000 h
Using the lamp with a LED bulb for 3 hours a day, such a bulb should work for over 13 years.

VOLTAGE / CAP TYPE

Both bulbs have a G4 cap and are powered by 12V, so it is necessary to use a power supply. In my opinion, this is an advantage, because using a 100-240V plug-in power supply enables such a lamp to work anywhere in the world.

WHAT ELSE
You Should Keep In Mind

Lighting effects are largely influenced by the distance between the bulb and the gourd walls. The bigger the distance (bigger gourd), the clearer the patterns. Each hole also casts a smaller light spot, so the light is less diffused. Patterns cast by such a lamp are clearer, even in a larger room.

Apart from the fact that a larger gourd gives more possibilities, the light patterns are the reason why I really like to create floor lamps.

Drilling holes in the gourd is not enough. If you want each hole to cast light, it must be drilled towards its light source.

Therefore, it is best to drill holes with a pre-mounted luminaire and a bulb to control the correct direction of drilling. That’s what I carefully examine having drilled a hole.

But the technique of drilling is the topic for another post.

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Jane Mawson · 23:32 · 27/04/2020 - Reply

Could you recommend a 120/220 volt bulb?

Przemek Krawczynski · 11:40 · 29/04/2020 - Reply

Sorry, the only 230 V light bulbs that I have been using were the old type of filament bulbs. I don’t know any 120 / 220 V bulbs which could be good because I simply weren’t interested in them.

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