This question comes up about once per month so there should be some good answers in some of the older threads.
if you use the white paper, you would set the lettering color in your artwork to white which will tell the printer to not print anything in those areas leaving the white decal paper to show thru.
If you use the clear decal paper you would do the same thing. However, you WILL have to paint a white patch the same size as the decal in order for the white to show thru and also cause the rendering of the other colors to work.
There are a few guys on here who have had good succes with this process and I am sure they will chime in as well
What brand of decal paper do you have? Evan Design white paper will turn clear if sprayed with a solvent-based top coat. You can mask off the letters you want to stay white.
You can also use a paint program to fill in the letters (use a slightly off-white so you can see it).
Or, you can cut out the letters with a hobby knife.
If you print on clear decal paper, anything that should be “white” will come out clear. “Yellow” will be very pale indeed, as will any pastel color. The darker colors will look pretty good.
But, if you apply the decal to a white surface, all the intended shades will be magically restored. The hard part is matching the edge of the decal with the surrounding color of the model. For engines and rolling stock, that’s tough unless you’re going to use weathering to mask the decal edges. For structures, though, you can use the artwork itself to make the transition.
This sign is printed on a wood plank fence made with coffee stirrers. I measured the sign carefully, and then used cheap acrylic craft paint to put a white rectangle on the fence, just smaller than the sign itself. I just did this with a paintbrush, and I gave it two or 3 coats. I did this one with flat paint, but gloss works better, and that’s what I use now. The actual border of the white rectangle is under the dark black border I added to the sign.
The fence is about an inch high. I used a sharp hobby knife to “rip” the coffee stirrers lengthwise. This way, the planks weren’t too wide, and they were also somewhat uneven. The width of the fence will depend on what size coffee stirrers you’re able to “liberate” from whereever it is that you get your coffee.
I use the Evans Design Decal paper and have had good success creating white letter on colored background decals. The real trick is matching the background color to that of the model. The way I do this is to first print out a row of small color swatches across the top of the page of decal paper. Choose a color you think is close to the desired background for the first swatch, then several swatches in progressively lighter shades, then several in progressively darker shades. Run a trial print on the actual decal paper. Don’t use another sheet of regular paper as it will take the inks differently and not produce the same colors as on the decal paper. Compare your swatches to the model, choose the closest or adjust the shades and try again. Once you’ve found the correct background color, design and print all of the white letter decals you need for as many models of the same color as possible so as not to waste decal paper. Be sure to save the file so you won’t have to search for the background color again for future decals. Plan your decal backgrounds so they can be trimmed to match the dimensions of the model panels you are applying them to as this will help hide the decal edges. Do not overspray the Evans Design decal paper with solvent type clear coats such as Dull Cote as this will permanently turn the white background clear (a neat trick when you actually desire this change). Use acrylic clear coats instead. Don’t worry when you see the white background turn clear when you wet the decal with water, setting solution or acrylic clear coat. The background will return to an opauqe white as it dries. I would imagine that the generic white background decal paper you’ve already bought could be used in a similar manner. Give it a try and let us know what happens. Also note that, while the Evans Design decal paper does not, most brands of decal papers require a clear overspray to seal the inks on the decal. I have only smeared one decal I made with the Evans Design decal paper and that was entirely