Which bulb to use in a wooden lamp: lumens, Kelvin and watts explained
A wooden lamp can turn out perfect or dull because of the bulb alone. A light that is too white leaves the wood grey and lifeless. A bulb that gets too hot dries out the fibre and, close to a raffia shade, is a risk. The good news is that getting it right is simple, as long as you know which numbers to look for on the box.
The short answer: LED bulb, E27 base, 15 W at most, between 2200K and 2700K, with a colour rendering index (CRI) of 90 or more. The rest of the article explains the reasoning behind each of these points, so you can decide with confidence when you are standing in front of a shelf of bulbs.
Forget watts, look at lumens
For decades we chose bulbs by watts, because with an incandescent bulb the power consumption gave a good idea of the light it produced. With an LED it no longer does. The amount of light is measured in lumens (lm), and is always shown on the packaging. This table helps bridge the gap with what we are used to reading:
| Old incandescent | Equivalent lumens | Approximate LED |
|---|---|---|
| 25 W | 249 lm | 3 W |
| 40 W | 470 lm | 5 W |
| 60 W | 806 lm | 8 W |
| 75 W | 1055 lm | 10 W |
| 100 W | 1521 lm | 13 to 15 W |
For an ambient lamp, on a side table or a shelf, 200 to 470 lm is enough. For reading next to the lamp, count on 800 lm or more. And remember that when there is a shade, part of the light is held back by the weave: the tighter it is, the more light is lost and the more lumens you should allow for.
The colour of the light: why it should not go above 3000K
Colour temperature is measured in Kelvin (K). The lower the number, the warmer and more orange the light, and it is that warm light that brings wood to life. The image at the top shows it well: the same olive grain, with an amber light on the left, warm white in the middle and cool white on the right.
| Temperature | What the light is like | On the wood |
|---|---|---|
| 2200K | Amber, like a candle | Brings out the honey and brown tones. Ideal with exposed filament bulbs |
| 2700K | Warm white | The balance for everyday use. Respects the real colour of the piece |
| 3000K | Soft white | Still acceptable, especially on pale woods such as pine (CACTUS) or plane tree (CÔA) |
| 4000K or more | Neutral to cool white | Not recommended. The wood loses its warmth and turns greyish |
The number almost nobody reads: the CRI
The colour rendering index (CRI, or Ra on some packaging) tells you how faithfully the bulb shows colours as they really are. A cheap bulb, with a CRI of 80, flattens the tones: the grain of ZAMBUJEIRO and the bark of GUARDIÃO look almost the same brown. With a CRI of 90 or more, the difference is visible to the naked eye, and it is what separates wood with depth from flat wood.
Why LED only, and 15 W at most
An incandescent or halogen bulb turns most of its energy into heat rather than light. Next to natural wood and paper raffia, that heat dries out the fibres, can deform them and is a fire risk. That is why, for all our pieces, we specify only LED bulbs up to 15 W, as stated in the manual that comes with every lamp.
Even an LED warms up a little near the base. Do not cover the lamp while it is lit and let it cool before changing the bulb.
Bulb on show or inside the shade?
On pieces without a shade, such as RECO or ZAMBUJEIRO, the bulb is part of the design and deserves the same care as the wood. An LED filament bulb, in amber or clear glass, is the natural choice: it looks good lit and unlit, and its warm tone suits the grain.
On pieces with a raffia shade, such as ALBURNO, or when you fit one of our lampshades to a lamp of your own, it is the shade that filters the light. Part of it is always held back, and the glow of the bulb, whether clear, milky or opaque, shows through the weave. What changes is the intensity of that effect, which depends mainly on whether the weave is more open or more closed. So the choice between them is more a matter of use and taste: filament gives a livelier, more decorative light, milky gives a more even light, and the latter also tends to be cheaper. We explain more about how raffia works with light in How to create cosy lighting.
Bulb base and dimming
All our pieces use an E27 base, the common wide screw, so any E27 LED bulb will fit.
If you want to adjust the brightness, the packaging must say “dimmable”, and the dimmer must be LED-compatible. A non-dimmable bulb connected to a dimmer will flicker or hum.
To take to the shop
- LED, E27 base
- 15 W at most
- 2200K to 2700K
- CRI 90 or more
- Filament on pieces without a shade; with a shade, filament or milky, depending on the effect you want
- “Dimmable” only if you have a dimmer
A good bulb is half of a lamp’s light; the other half is the wood it sits on. Every LAMS Woodcrafts piece is handmade from reclaimed wood, and was designed to receive a warm, low light that lets it be what it is. You can see how it looks in our table lamps, floor lamps and lampshades, or browse all the pieces available. If you have questions about the bulb for a specific piece, write to us at info@lamswoodcrafts.com.