I need it to be opaque

[anemul]

Hello all. I enjoy RC racing. I need to make some number decals. When I make them in GIMP 3.08 revision 2 and print the images onto transparent decals, the graphics are way too transparent. I'm not sure what information you need, so here is the basic:
Windows 11
GIMP 3.08 revision 2
I have an older Epson 837
At this point I have spent more on decal paper than I would have if I had had someone make them for me. That's limited, though. Any ideas?

[rich2005]

printer ink cyan / magenta / yellow is very transparent  except for black which is a bit denser and of course there is no white.

Just a guess, but I think your transparent media is much the same as the transparent media for overhead projectors.  I have used that in the past and of course, in use,  the slides get projected onto a white screen.

Just pulled one out, layed it on green / white background, very quick photo, just to show backing matters.

   

Are you planning on painting a white background for the transfer? No real way to make colours denser, there will be a quality setting somewhere in the Epson Windows Printer Driver (last Epson I had was 25 years ago) and make sure the image pixels-per-inch (ppi) value is 300.  Depending on the image and the acuracy of the printer paper feed, it might be possible to print twice  (maybe)