Newbie Questions - Converting images to CMYK and printing using Rich Black using Epson ET-2810 printer onto Transparencies for Screen Printing

[Karen France]

Hi Guys, I'm trialing Designer and Photo in the hope that they can solve my problems with the following projects.  I'm trying to print onto transparencies for creating screens for screen printing.  My images are just black and white (no grey - at least there shouldn't be any grey) and I've been told that they need to be printed using CMYK and rich or composite black to make the black opaque enough so light can't get through it.

I've attached a couple of example files - one an edited photo (inkscape), the second an image drawn in Procreate.  

Can anyone tell me how to convert the black into the rich or composite black  - I'm going round and round in circles and am about to give up and just print it out 3 times and lay them on top of each other 😞

Any help would be really appreciated.

[Komatös]

Hi @Karen France

In Affinity Photo or in the Pixel Persona in Designer select the move tool. In the upper info line you'll find "K only". Press on the button to activate.

[walt.farrell]

5 minutes ago, Komatös said:

you'll find "K only". Press on the button to activate.

That's not going to work to get rich (composite) black, is it?

[Karen France]

I've had a closer look at both images and I seem to have grey pixels around the edges - I'm not sure how I can get rid of these.

[v_kyr]

49 minutes ago, Karen France said:

I've had a closer look at both images and I seem to have grey pixels around the edges - I'm not sure how I can get rid of these.

You can trace/vectorize those after 2 colors (just black & white, no greylevels) in order to get rid of any grey colors inside ...

• AubracTree.afdesign
• AubracTree.pdf
• AubracTree.svg
• Shell6.afdesign
• Shell6.pdf
• Shell6.svg

For printing check out what your printer supports here, aka if it via it's printer driver converts sRGB either way to a cmyk print, or if you have controll of explicite cmyk based greylevel printing (only the blacks here). - Make some test prints on plain paper first in order to be sure about the output, before printing on transparencies.

[R C-R]

3 hours ago, Karen France said:

I've had a closer look at both images and I seem to have grey pixels around the edges - I'm not sure how I can get rid of these.

A very crude way to do that is to use the Flood Fill Tool with Continuous off to select all of the transparent & the lightest grey pixels of the image. (You may have to adjust the Tolerance so this does not select too many of the dark pixels. Experimentation may be necessary to get the best results.) Press Delete to erase the selected pixels.  Finally, use the Paint Brush Tool set to black to paint over the selection, converting all the dark grey pixels to black.

Attached is AubracTree black only.afphoto with the history included so it may help you understand how that works.

Note: I did this using the RGB color space in the png document you included, but if you convert it to CMYK to begin with & paint with black set to whatever rich black works best with the printer, it should give you more or less what you need ... I think! 🤔

[Karen France]

Thank you so much v_kyr and RC-R, I'll give both of those a go today.  I really appreaciate you taking the time to help me 🙂

[Komatös]

I wonder if an inkjet printer that uses RGB color profiles can handle CMYK color profiles? And I believe, he can't

And an inkjet printer will, in my experience, never print properly 'opaque' on transparencies.