Splitting Vector Patterns or Groups Using Shapes

[FreakinAwesome]

I am new to Affinity but feel strangely empowered to take on the world with my new found freedom to create. Thank you, and forgive me for being a noob.

 

I am creating a business card and have made a repeating watermark background of the logo, which is made up of thousands of little vector shapes. I want this background to behave distinctly differently depending on what it is overlaying. On the white background I want it to appear exactly as it is, however over the picture I would like to create a vector object with special print instructions for the print shop to use "Spot UV" instead of ink. Seems the easiest way to do this is to create a shape or a hard line along the break in the picture and split the object right on the line, cutting the tiny little vector objects in half one side to it's own object printed in faint blue ink and the other being a mask for the print shop to use precision UV coating to watermark the logo over the picture.

 

Every time I place an object over the watermark repeating background I am unable to subtract, and when I choose "divide" nothing happens. What am I missing? Do I need to duplicate the background and create two masks?

[MEB]

Another alternative assuming you have all vector shapes that compose your pattern in a single vector layer (if not press Add Layer button on the bottom of the Layers panel and drag all objects that compose the pattern to inside that layer) is to duplicate it, draw a shape similar to the image in your screenshot and drag the pattern layer over the shape you just created to use it as a clipping mask in the Layers panel. This way only the part of the pattern that lays inside the shape will be visible. Since you are not moving any shapes on the canvas both copies of the pattern will remain aligned.

Below the clipping shape you will place your image and below the image you will have the full pattern (only visible on the right since the left part is covered by the image itself). Sample file attached with a shape clipping a pattern.

clipping_mask_sample.afdesign

[FreakinAwesome]

Very sorry I never thanked you for the information. I applied what you taught me immediately and my friend was pleased with the outcome.