Editing contents of a spot channel for printing

[RatFiend]

I am using Photoshop to prepare a scan of a painting for printing. The print will have metallic ink added to certain parts of the image. The print shop has asked me to "create a spot color channel that covers any area you want enhanced by the effect." I am new to this and all of the resources I've found so far about how to do this involve selecting an entire color range and turning it into a spot channel. However, only a small amount of this image (not neatly selected by a color range, etc) needs to be added to the spot channel for the metallic ink, so it seems like it would be more efficient to manually mask or erase the image to isolate the desired areas. Can anyone offer advice on the best way to do this? Like, can I simply copy the image into a new layer, delete anything I don't want to be printed with the highlight, and make that the contents of an additional spot channel?

 

[thebestcpu]

Hi @RatFiend

Keep in mind your print shop is your friend and should be able to answer most of your questions as well.

- Create a Spot channel in the Channel Panel dropdown options with "New Spot Channel". Also, when saving your file make sure you save to an appropriate format that saves Layers (checkbox checked) and also the Spot Channel checkbox checked.

- With that, the Spot channel is just another channel Layer (greyscale) that represents where the ink should go or not go. You can create that channel by any means you like as you had mentioned and copy and paste that result into the channel.

Key elements of which I am not aware for your project yet you know or your print shop will know is
- Are you working in RGB or CMYK mode with a spot channel? What one needs to know is does black / white in the spot channel represent place spot ink / place not spot ink respectivly or vise versa?
- Do you only need to specify the areas to put the metalic effect (as just a black and white image) or do you need to specify how much of the spot color you want in an area by using grayscale in the Spot Channel
- As I understand, for some type of prints the Spot Channel can be just black and white though you need to set the Solidity setting for the Spot Channel to represent the opacity of the Spot color you want.

I am assuming you either have that information or will get it from the Print Shop so you have no surprises.

Also note that I am definitely not a spot channel expert and another Forum member may jump in with more accurate information. I will provided a couple links that might be helpful as well:

https://helpx.adobe.com/photoshop/using/printing-spot-colors.html

https://gcp.ink/metallic-dry-inks-photoshop/

Mike’s Technical Tip: Know Your Process, Spot, and RGB Colors

Hope this helps some
John Wheeler