The wavy bands are moiré. They appear when you lay one regular, see-through structure over another that is not quite identical, so the spacing or the angle is slightly different. On a table the layers sit still and flat. On a moving body, the angle and spacing between layers keep changing, so the bands appear and move.
What makes a sheer layer shimmer or show wavy bands?
A sheer layer shows wavy bands when its threads or holes form a regular grid, and that grid sits over a second regular grid that is slightly different. This effect is called a moiré pattern. Two patterns produce it only when they are not completely identical, but displaced, rotated, or of slightly different pitch. “Pitch” here means the distance from one thread, or one hole, to the next.
Several sheer fabrics are regular grids. Organza is a thin, plain-weave, sheer fabric. Voile is a lightweight, sheer, plain-weave fabric. Tulle is netted in a hexagonal pattern with small openings. Under a magnifying glass, chiffon resembles a fine net or mesh. So a chiffon overlay on a dress, or an organza overlay on a kaftan, is a fine grid sitting over whatever is underneath.
Two facts from the geometry explain what the buyer sees.
- The bands are much bigger than the threads. When two identical grids are turned by a small angle, the distance between bands is roughly the thread pitch divided by the angle (in radians). The same source gives this small-angle approximation. A very small angle gives very wide bands. That is why threads you cannot see one by one can still make bands you see across a room.
- The bands move faster than the fabric. When one layer moves, the moiré pattern moves at a faster speed than the layer itself. A small sway of a chiffon kaftan can send the bands sweeping across the garment. This is the “shimmer” the wearer sees, and the reason the effect is easy to miss on a still sample.
This is not the same as a moiré fabric
Some fabrics carry a moiré look on purpose. “Moiré” is also the name of a textile, historically silk, with a rippled, “watered” look. That finish is made in the mill by calendering. Ribbed rollers press the cloth and flatten some threads while others stay round, and the two kinds of thread reflect light differently. The pattern is fixed into one fabric. It does not move when the wearer moves.
Layering moiré is different. It is not in either fabric. It exists only where two layers overlap, and it changes every time they shift. If a buyer wants a watered look, order a moiré-finished fabric. If a buyer does not want bands on a layered dress, the fix is in how the layers are chosen, cut and joined.
Which pairings set it off?
The pairings that set it off are two regular grids of similar pitch: sheer over sheer of the same fabric, net over net, and sheer over a fine stripe, check, mesh or geometric print. The closer the two grids are in pitch and angle, the wider the bands, and the faster they sweep across the fabric as it moves. A plain, opaque, unpatterned lining removes one cause: there is no second, different see-through grid behind the sheer. It does not remove every cause. Where a full or gathered sheer folds over itself, or where two sheer layers overlap, the fabric is still two copies of one grid, displaced or rotated against each other, so bands can still appear. A sheer held away from a light lining can also make bands with its own shadow, the effect known as shadow moiré.
Georgette needs its own note. Georgette is woven from highly twisted crepe yarns, alternating S- and Z-twist, which give it a crinkled surface. Chiffon also uses alternate S- and Z-twist crepe yarns, and the twist puckers the fabric slightly. A puckered grid is less regular than a flat one. Moiré needs regular grids, so we would expect weaker bands from georgette than from organza. That is a reasoned expectation, not a measured result. Test your own fabric.
| Pairing (top layer over under layer) | Garment examples | Risk | Why |
|---|---|---|---|
| Organza over organza | Layered dress skirt, organza kaftan with organza lining | High | Two flat plain-weave grids of the same pitch. Any small angle between them makes wide bands. |
| Net or tulle over net or tulle | Tiered net dress, resort-wear layered skirt | High | Two regular hexagonal grids. The open holes give high contrast. |
| Voile over voile | Double-layer voile kaftan or beach dress | High | Two plain-weave grids of the same pitch. |
| Any sheer over a fine stripe, check or geometric print | Chiffon overlay on a printed slip dress | High | The print is a second regular grid. If its pitch is close to the sheer’s pattern, bands form. |
| Any sheer over a mesh lining or mesh panel | Organza kaftan over a power-mesh slip | High | Mesh is a regular grid of holes. |
| Chiffon over chiffon | Double-layer chiffon kaftan or maxi dress | Test it | Chiffon looks like a fine mesh, but the crepe twist puckers it slightly, so the grid is less regular. |
| Georgette over georgette | Double-layer georgette dress or kaftan | Test it | The crinkled crepe surface breaks up the regular grid. |
| Sheer of one fabric over a sheer of another with a very different pitch | Net overlay on a chiffon dress | Varies, test it | A bigger pitch difference makes the bands closer together and finer. Whether they are still visible depends on the fabrics. |
| Any sheer over a solid, opaque, unpatterned lining | Chiffon kaftan with a plain satin or jersey lining | Test it | There is no second, different see-through grid behind the sheer. Bands can still form where the sheer folds over itself or where sheer layers overlap. |
The “bigger difference, finer bands” line comes from the same geometry. For two parallel grids, the bigger the discrepancy in pitch, the closer the dark and pale zones.
Does the angle the layers are cut or stitched at change it?
Yes. The angle between the two layers sets the size of the bands. A small angle between two layers of organza or net gives wide bands. A larger angle gives narrower bands. This follows directly from the small-angle relation above. We do not give a “safe” angle, because no source we found states one. The right angle depends on the pitch of your two fabrics, and only a test shows it.
Three things in the cut and the make change the angle or the pitch on the body.
- Grain line of each layer. If the chiffon overlay and the chiffon under layer of a dress are both cut on the straight grain and stitched into the same seam, their threads run almost parallel. Almost parallel means a small angle, and a small angle means wide bands.
- Bias cuts. True bias is 45 degrees to the warp and weft, and woven fabric is more elastic in the bias direction. A bias-cut organza or voile layer stretches as the wearer moves. Stretch changes the pitch, and a change in pitch changes the bands. So a bias-cut layer in a kaftan or a slip dress can make bands that change with every step.
- Drape and folds. In a full kaftan or a gathered resort dress, the layers fold and twist. Each fold changes the local angle between the two grids. The bands then follow the folds and move with them.
How the layers are joined also matters. Layers that are joined only at the neckline or waist are free to slide over each other. Sliding moves the bands, and the bands move faster than the layers. Layers that are tacked or stitched together at more points slide less. This reduces movement of the bands. It does not remove the bands, because the two grids still overlap. Hem and slit construction also decides how freely the layers move; see our note on side slits on kaftans, skirts and dresses.
How to specify the overlay so the effect stays out of bulk
Specify the overlay by naming both layers exactly, fixing the grain line of each, and making “no visible moving bands in wear” an approval condition for the sample. Moiré lives between two layers, so a spec that names only the top fabric leaves half the cause open.
- Name both fabrics. Write the overlay fabric and the under-layer fabric on the tech pack: for example, “polyester chiffon overlay over polyester satin lining”, not “chiffon dress, lined”. If the under layer is a print, attach the print artwork, because the print is the second grid.
- Mark the grain line on every pattern piece of every layer. If you want the overlay and the under layer on different grains, say so on the pattern, piece by piece. Do not leave the under layer’s grain unmarked on an organza, voile or net dress.
- Choose the under layer with moiré in mind. If the design allows, a solid, opaque, unpatterned lining under a chiffon or georgette kaftan removes a second, different see-through grid. It does not stop bands where the sheer folds over itself or where sheer layers overlap, so still check the sample in wear. If the design needs sheer over sheer, record which pairing was tested and approved.
- Lock the approved fabrics. The bands depend on the pitch of each fabric. A different construction of “the same” chiffon, organza or net has a different pitch, so it can give different bands. Write the approved fabric references into the order, and ask to be told before any substitution.
- State how the layers are joined. Write where the overlay is attached to the under layer: neckline only, neckline and waist, or tacked at given points. This controls how much the layers slide in wear.
- Write the approval condition in plain words. For example: “Approved sample shows no visible moving bands when worn and moved, in daylight and under shop lighting.” Describe the viewing conditions you care about. There is no industry number for this, so define it yourself.
- If you want a watered look, order it as a fabric. A moiré-finished fabric is made by calendering with ribbed rollers. Do not rely on layering to give a controlled pattern.
How to check for it at the sample stage
Check for it by moving the layers, not by looking at a flat sample. Moiré in a chiffon dress or an organza kaftan depends on the angle and the movement between layers, so a still garment on a table can hide it.
- Swatch test before cutting. Lay the overlay fabric over the under-layer fabric, in good light. Turn the top layer slowly, then slide it. If bands appear and sweep across, the pairing is sensitive. Repeat with the layers on the grains you plan to cut.
- Use the real fabrics. Test the actual overlay and lining that will go into bulk, including the actual print if the under layer is printed. A different chiffon or net has a different pitch.
- Try the sample on a person or a moving form. Walk, turn and sit. Watch the skirt of the dress, the body of the kaftan and the gathered areas, where the folds change the angle most.
- Look in more than one light. Look with light from in front, from the side and from behind the garment. Back light shows the open grid of a sheer most clearly.
- Do not judge only from a photo or video. A camera sensor is itself a regular grid of pixels, so a photo of a fine fabric can show bands that are not visible to the eye. Confirm by eye, in person or on a live video call.
- Record what you approved. Note the fabric references, the grain of each layer and how the layers are joined. Put the note with the approved sample, so bulk is made to the same build.
KK Fashion Exports has made dresses, kaftans and resort wear for buyers worldwide since 2003. Our minimum for dresses, kaftans and other garments is from 200 pieces per style, per colour. Send us your tech pack with both layers named, and see our kaftan range and our note on polyester georgette kaftans.
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