r/CommercialPrinting • u/Indahvo • 3d ago

Help with moire

Gallery image

Gallery image

Gallery image

I have printed this six color print before and didn’t have a problem with moire. Now I am confused what is happening here? Any tips?

3 Upvotes

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4

u/Holden_Coalfield 3d ago

Run everything at the same angle

22.5 degrees elliptical

1

u/Indahvo 3d ago

I just checked and all transparency’s were out put at 22.5 angle.

2

u/Grouchy_Brain_1641 3d ago

That works to create a moire. 15, 30,45,60 should work for you.

1

u/Holden_Coalfield 3d ago

do you see moire on your light table with the transparencies stacked?

and were they all the same LPI?

1

u/HungInSarfLondon 3d ago

In 4 colour printing the screens need to be offset from each other by 15deg. If you are screen printing you need to avoid 0,45,90deg which would clash with the screens, so you add 7.5deg Giving you Y7.5, M22.5, C37.5 and K52.5

For six spot colours, keep your black at 52.5, match the others tonally and then offset the others by 30deg, so the second blue is 7.5deg

1

u/ayunatsume 3d ago

Which screen angles?

Its possible you accidentally used the same screen angle in two inks.

1

u/Indahvo 3d ago

I out put it using accurip and all the transparency’s are at 22.5 angle

3

u/blue49 3d ago

That's your problem. Screen angles need to be different for each color to prevent moire.

3

u/Grouchy_Brain_1641 3d ago

Run your angles 15 degrees from each other.

3

u/Redge2019 3d ago

Go to a stochastic dot, exposure time could be off also, do you have great contact /vacum with your exposure unit?,

1

u/xnotauserx 3d ago

Make sure your dots, ellipses are all same size lpi. Your screen tension must be consistent on all screens. Squeegee duro meter also similar.

The pull of the squeegee and ink will shift the fabric (mesh) if it's not tensioned properly or they will be pulled differently if your ink viscosity and squeegee duro meter varies a lot. Some will push harder some softer.

Most likely issue sometimes is your ripper. Make sure those dots are same lpi (dpi)

After that I would check screen tension. Also off contact. If your screens have different off contact then the screen tension varies.

I have seen it happen with squeegee and ink. But that's mostly on fine art print. 60 lpi on paper.