Why black velvet photographs blue, and what that means buying online

A black velvet dress in a photograph is very often not black. It is navy, or charcoal with a blue sheen, or in a bad shot nearly royal. The fabric has not been dyed wrong and nobody has retouched it. Velvet is a mirror with a texture, and what it hands back to a camera is the colour of the light rather than the colour of the dye.

Two kinds of reflection

Light arriving at any surface splits into two parts. One part goes into the material, bounces around among the dye molecules and comes back out missing whatever the dye absorbed. That is the part carrying the colour, and in a black fabric there is almost nothing left of it by the time it returns.

The other part bounces straight off the surface without going in, and it keeps the colour of the light source. On a matte cotton tee that contribution is small and diffuse and you never notice it. On velvet, the pile presents thousands of tiny curved fibre surfaces at every angle, so there is a great deal of it, and it is the brightest thing in the frame.

So a black velvet garment reads as whatever colour the light in the room is. The dye has nothing to contribute and the sheen has everything.

Why the cast is usually blue

Daylight is blue rich, and open shade and overcast sky are bluer still, because what reaches the subject is scattered sky rather than direct sun. Measured as colour temperature, direct sun sits near 5500K, overcast around 6500K, and open shade on a clear day can run to 8000K or beyond. Higher numbers mean more blue in the light.

Almost all clothing is photographed in daylight, or in softboxes built to imitate daylight, so the sheen on the pile is blue. Shoot the same dress under an old tungsten bulb at about 2700K and the sheen goes warm brown instead. Neither photograph is a lie about the dye and neither one is useful on its own.

A camera's white balance corrects for the main light only. If the main light is a lamp and a window is also contributing, the correction is set for the lamp and the window's cooler light lands on the pile uncorrected. Mixed lighting is why one photograph in a set can look blue while the others look fine.

What the camera does after that

Cameras have far less room in the shadows than in the highlights. A near black garment occupies a handful of levels at the very bottom of the file, and once that has been saved as an eight bit JPEG, compressed and sharpened, small colour errors down there get stretched into a visible cast.

Phone cameras make it worse deliberately. Night and portrait modes lift shadows to recover detail, and lifting a black that carries a blue sheen gives you a navy garment. The processing is doing what it was designed to do.

Then the screen you are reading on applies its own warmth setting, which on most phones shifts through the evening. A dress can genuinely look like a different colour at eleven at night than it did at lunchtime.

Reading a product photograph properly

Find something in the frame whose colour you already know: a white collar, a white wall, a sheet of paper. If that white is blue, the whole image is blue and the garment is blacker than it looks. The doll collar dress is easy to judge that way, because the collar is white and any cast shows up on it before it shows up on the velvet.

Then compare several photographs taken at different angles. A real colour survives a change in light. A cast moves with it. If a garment reads brown in three separate shots from three separate sellers, that is more likely to be the dye than the lighting.

Treat a flash lit photograph as the best guide to the colour and the worst guide to the texture. A flash near the lens flattens the pile out and the garment comes back looking like plain cloth.

When the cast is actually a warning

Polyester takes black well and holds it. Where a stated black is really a very dark something else, it is usually a mixed fibre fabric, because two fibres in one cloth take the same dye bath differently. The same applies when a lace or mesh trim is a different material from the body of the garment.

On a piece that combines velvet with something sheer, like the ruched velvet with mesh sleeves, the two components can read as a visibly different black in daylight even when they match perfectly under a bulb. That is not a defect, and it is a great deal easier to know before the parcel arrives than after.

Where it matters most is matching. If you want two black pieces to read as one outfit, buy them together, from one source, at one time. Dye lots drift, and the sheen on a pile fabric makes a small difference look like a large one. A black velvet top against a black pleated skirt bought two months apart is a gamble on two different factories agreeing about black.

What we do about it

We do not push a garment photograph to a flatter, deeper black than the camera actually saw. It is tempting, because the corrected version looks better on a product page, and the first thing that happens is somebody opens a parcel containing a dress they did not think they ordered.

A photograph of black velvet that looks slightly blue is more honest than a corrected one, provided the page says what the fabric is. We would rather explain the physics than retouch it away.

If you are deciding between two blacks and the photographs are not settling it, ask us before you order. We take no returns, so a colour you did not expect is money you do not get back, and an email costs neither of us anything.

Questions people actually ask

Why does black velvet look blue in photos?

Velvet's cut pile reflects a lot of light straight off its surface, and that reflection keeps the colour of the light source rather than the dye. Daylight and studio softboxes are blue rich, so the sheen reads blue while the fabric itself is still black.

How can I tell if a dress is navy or black in a photo?

Look for something in the frame whose colour you know, such as a white collar or a white wall. If that white looks blue, the whole image has a blue cast and the garment is blacker than it appears. Compare several photographs taken in different light.

Does black velvet fade?

Any black fabric fades in sunlight, and velvet shows it as a brownish or grey cast across the pile rather than as an even lightening, because the fibre tips weather first. Store it in a wardrobe rather than on an open rail by a window.