Silkscreen halftone Gradient Printing - Gradient Banding issue

[agile_Spirit8314]

I am working on a silkscreen printing project, creating gradients as halftones for film printing.

At the 50% point, where the halftone dots transition into a checkerboard pattern,

gradient banding occurs.

Is there a solution to this?

[Stephen Marsh]

There are multiple ways to create halftone screens in Photoshop (which isn't a proper halftone screen RIP). How specifically are you creating your screens and at what resolution and LPI value?

https://the-print-guide.blogspot.com/search?q=Euclidean&m=1

https://the-print-guide.blogspot.com/search/label/Dot%20Shapes?m=1

https://the-print-guide.blogspot.com/search/label/AM%20Screening?m=1

[agile_Spirit8314]

I am working with bitmap at 2500 dpi and applying 50 LPI (lines per inch). The screen mesh used is 300. I noticed banding occurring at the 50% point of the halftone pattern, where it turns into a checkerboard. There is dot loss, dot gain, and the gradient transitions are not smooth and look abrupt. What should I do?

I am working on a single-color print gradient, not a two-color print.

[Stephen Marsh]

@agile_Spirit8314 

The bitmap mode halftone conversion is generally best, I would usually avoid the more "artistic" halftone effects. This will transition from round/square/round which is generally best.

What is your K angle? 45° or shifted to something like 52.5°?

Do you have a TVI/Dot Gain curve applied to the contone file before the bitmap mode conversion?

How are you creating your positive films? Inkjet? Laser printer?

[agile_Spirit8314]

The angle I use is 22.5°. I haven't tried the TVI/Dot Gain curve. Could you provide more details on that? I attempted adding noise before switching to bitmap mode. It reduced the banding, but it was still present. I believe the film is from a laser printer. I don’t develop the film myself; I outsource it to a company that creates the silkscreen films.

[Stephen Marsh]

The angle I use is 22.5°. I haven't tried the TVI/Dot Gain curve. Could you provide more details on that? I attempted adding noise before switching to bitmap mode. It reduced the banding, but it was still present. I believe the film is from a laser printer. I don’t develop the film myself; I outsource it to a company that creates the silkscreen films.

By @agile_Spirit8314

Why 22.5° for a single colour job over the more common 45° or 52.5°?

Sorry, I can't help with the TVI/Dot Gain compensation required. Do your files print too dark or too light? If not, then you wouldn't need to worry.

If things were printing way too dark (whatever that means), then I would start with a compensation adjustment of 20% at the 50% point where 50% would become 30%, however, there are of course more precise methods than guesswork. This is an extreme example, the lightening may only be 5-10% and may require multiple values entered at different points.

[c.pfaffenbichler]

Could you please post screenshots taken at View > 100% with the pertinent Panels (Toolbar, Layers, Options Bar, …) visible? 

[agile_Spirit8314]

I am using Korean, not English, within the program. Please keep that in mind. This is the state at 100% view. The resolution is 2500 dpi, and the LPI is 50.

[c.pfaffenbichler]

I fail to see banding in the screenshot, so are you talking about the actual printed result? 

What material are you printing on? 

[agile_Spirit8314]

Yes, there is banding in the printed results. I am doing silk screen printing on glass. I used a mesh of 300 and an LPI of 50.

[c.pfaffenbichler]

Could you post a scan of the print with the banding? 

Have you tried smaller lpi/larger dots?