Reduce colours for screen printing: 40 colours to 8 screens

A design that looks like 10 colours on screen often holds thousands of shades. A screen printer can only print the inks you give them, one screen per ink, so the file has to come down to a fixed number before anyone engraves a screen.

This guide shows how to take a busy floral, the kind of saree or dress-material print that arrives with 40 visible shades, down to 8 screens without it looking flat.

Why colour count matters

Every ink is a separate screen, and every screen has to be made, engraved, fitted, registered and washed. More colours means more of each.

The machine also sets a hard limit. Rotary machine listings from Surat show 8, 12 and 16 colour models, and a smaller machine maker in Ahmedabad lists rotary models from 1 to 8 colours. A 40-colour file does not fit any of them.

So "bring it down to 8" from the printer is usually about both cost and the machine they have free.

What screens cost

Few printers publish their rates, and they change by city, mill and order size. These are the public figures we found. The online listings do not say whether engraving is included, so treat them as a floor.

Item	Figure found	Source and date
Rotary nickel screen (640/820/914 mm), as listed	₹1,400 per piece	IndiaMART seller, Ahmedabad, listing seen Oct 2026
Rotary printing screen, as listed	₹2,100 per piece	IndiaMART seller, Ahmedabad, listing seen Oct 2026
Rotary screen, ready to print	about ₹3,500 each, engraving extra	Indian textile professional, 2018
Strike-off sample	3 to 4 times the per-metre order price	Same 2018 comparison

The table below is an example only. It multiplies the 2018 figure of ₹3,500 per screen by the number of colours, before engraving, sampling and ink. Ask your printer for real current rates.

Colours	Screens	Example screen cost at ₹3,500 each
6	6	₹21,000
8	8	₹28,000
12	12	₹42,000
40	40	₹1,40,000 (and no machine to run it)

Example: Going from 12 colours to 8 removes 4 screens. At the example rate that is ₹14,000 saved on screens alone, for every new design.

Why the file has so many colours

Most extra shades are accidents. Soft brush edges, scanning, JPG compression and anti-aliasing all add in-between pixels where two colours meet.

A red petal on a green leaf can have a dozen browns along the edge. None of them is a colour you meant to print, but each one counts if you leave it in the file.

Real gradients are the other source: shaded petals, a faded border, a watercolour wash. These need a decision, because they will either become halftones or flat steps.

Plan your 8 inks first

Decide the inks before you touch any menu. Write them down with a swatch for each.

1. Pick out every colour you can actually see in the design, ignoring edge pixels. For a busy floral this might be 40.
2. Group shades that a buyer would call the same colour on cloth. One separation guide says colours within about Delta E 3.0 can often be merged without a visible difference.
3. Keep the ground and any colour that outlines or carries detail. These are rarely the ones to merge.
4. Mark light tints that sit next to a darker version of the same hue. These can become halftones of the darker ink.
5. Look for two inks that overlap to make a third (a fall-on), such as yellow over blue for green.

Tip: Agree on the screen count with the printer before you start. Ask if a halftone or a fall-on is acceptable on this machine and fabric, because it changes how many flat colours you need.

Reduce colours in Photoshop

Photoshop's Indexed Color mode is the usual tool for this. It maps every pixel to the nearest colour in a palette you choose.

1. Make a copy of the design and flatten it.
2. Go to Image > Mode > Indexed Color.
3. Choose a Custom palette and enter exactly your planned inks.
4. Set Dither to None. Every pixel then becomes one of your inks with hard edges, which is what a screen needs.
5. Zoom in and clean the stray pixels left along edges. Pencil tool, or Select > Color Range per colour, works well.
6. Convert back to RGB if you need to edit further, then build one spot channel per ink.

Posterize is a weaker fit. It sets a number of levels per RGB channel, so 4 levels can still give up to 64 colours (4 × 4 × 4), and you cannot choose which ones.

Textile CAD programs such as NedGraphics do the same job with more control: they reduce to a set number of flat and tonal colours, merge similar shades and clean the result automatically.

Warning: Dithering (Diffusion or Pattern) scatters dots of two inks to fake a third. It is the basis of T-shirt index printing, which usually needs 6 to 10 inks. On yardage, use it only if your engraver agrees.

Keep the look with halftones

A halftone prints a lighter tone of an ink as small dots from that ink's own screen. A 40% dot area of red reads as a pink, so the pink does not need a screen.

Fabric spreads ink, so textile halftones are coarse. One separation guide gives 30 to 55 lines per inch for rotary screens, much coarser than paper printing. Screen makers offer meshes from about 25 to 165, finer meshes holding finer dots.

Use halftones for soft shading inside a motif. Keep thin outlines solid, since a line made of dots can break up. The strike-off will show it.

A worked example

Here is how a 40-shade floral on a navy ground could map to 8 screens, or 7 if the fall-on works. The groups are an illustration of the method.

Group in the original	Shades seen	Becomes
Navy ground	3	Screen 1: navy
Reds and dark pinks	9	Screen 2: red, plus a halftone pink
Light pinks	5	Halftone from screen 2
Greens	8	Screen 3: dark green, Screen 4: light green
Yellows and golds	6	Screen 5: yellow
Olive accents	4	Fall-on: yellow over dark green, or Screen 6
Off-white highlights	3	Screen 7: off-white
Outline brown	2	Screen 8: brown

The result keeps the navy, the red flowers with shading, two greens for depth and a clean outline. What you lose is the smooth blend inside each petal, which becomes a stepped or dotted tone.

Check it on a strike-off

The preview on your monitor does not show fall-ons, dot gain or how a pink halftone looks on a navy ground. You see those only on cloth.

Ask for a strike-off on the actual fabric before the run. Check merged colours under daylight and store light, and confirm halftones did not fill in or vanish.

Note: If a merge looks wrong on the strike-off, it is far cheaper to change one channel now than to re-engrave a screen after the run starts.

Common mistakes

• Reducing colours on the JPG straight from WhatsApp, so compression noise becomes extra colours.
• Using Posterize and sending whatever colours it produced.
• Merging the outline colour into the ground, so the motifs lose their edges.
• Halftones too fine for the fabric, which vanish or fill in on the strike-off.
• Forgetting that each colourway needs its own ink approval, even on the same screens.

Next step

Plan the inks on paper, reduce with Indexed Color, clean the edges, then test on cloth. If the design has a fixed repeat, size it for the screen first using our rotary repeat size guide, and see the full textile colour separation guide for building the channels.

Our Channel Separation tool will split a design into spot colour channels for screen printing. It is coming soon, so join the waitlist to hear when it opens. To test different ink sets before you commit to screens, try a few palettes in the Color Variation tool.