Mesh and line count: where the number comes from

The rule: mesh divided by 4.5

Mesh count is threads per inch. Line count is rows of dots per inch. For a dot to hold, it has to bear on several threads rather than fall between them, and that is where the ratio comes from.

Shops quote it differently: some divide by 4, some by 5, some by 3.5. The middle gives you a working figure.

• 160 mesh. Around 35 lpi. One-colour work, heavy white on dark.
• 200 mesh. Around 45 lpi. Athletic wear, high-contrast graphics, cheaper shirts.
• 230 to 305 mesh. Around 55 lpi. The middle ground for simulated process and busy artwork.
• 305 mesh and finer. Around 65 lpi. Needs controlled exposure.

Above 65 on textiles stops being a question about mesh and becomes one about the whole process: emulsion, exposure, squeegee pressure. Shops that work up there do it deliberately and after testing.

A finer screen gives you less, not more

This is the least obvious part, and the one that costs people runs.

A screen holds a dot only between two sizes. Too small and it washes out with the emulsion. Too large and neighbouring dots bridge, and the tone goes solid. Those two limits are what your screen actually reproduces.

On the default profile, with a 0.13 mm minimum line and a 0.14 mm minimum gap, they land here:

• 35 lpi. From 3 to 97 percent. Nearly the whole range.
• 45 lpi. From 4 to 95 percent.
• 55 lpi. From 6 to 93 percent.
• 65 lpi. From 9 to 90 percent.
• 80 lpi. From 13 to 85 percent. A quarter of the range is gone.

So raising the line count for the sake of detail buys you a finer dot and a shorter range at the same time. A fade meant to die away to nothing stops at 13 percent and drops to bare fabric, and the shadows plug from 85 up.

Detail only wins if there is somewhere to put it.

What the shop profile does with this

The profile holds the line counts your shop actually runs, and one of them is the default. Out of the box that is 35, 45, 55 and 65, starting at 55.

Give an ink a line count outside that list and the program says so. It does not forbid it and does not quietly correct it: your shop may own a mesh the list does not know about, and then it is the list that needs editing, not the job.

The list is yours to edit. If you only print on 200 mesh, leave 45 in it and anything else will stand out immediately.

Finding your own number

A handbook gives you a starting point, not an answer. The answer comes from your mesh with your emulsion and your exposure time.

1. Output a wedge.A row of patches from 1 to 20 percent in one-point steps, at the line count you intend to use.
2. Print it normally.Same mesh, same emulsion, same squeegee, same ink.
3. Find the first whole one.The first patch that images completely without breaking up is your bottom limit.
4. Repeat at the top.From 80 to 99 percent. The first one that plugs into a solid is your ceiling.
5. Put it in the profile.Convert those percentages into a minimum line and gap, and from then on the program works from your numbers instead of average ones.

An evening of work. After it, every screening decision stops being a guess.

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