printing on dark paper

The issue here is the transparency of the pigment in the ink you use. You need opaque pigment for the ink to really show up on the magenta paper. Metallic gold should work well because most metallic gold these days is made of aluminum pigment, with a little yellow in it to make a gold color. The aluminum particles are basically opaque flat flakes, which when printed, tend to lay down flat and make a continuous layer. This does a good job of hiding the substrate, and this process is called “leafing.” The more the pigment particles “leaf,” the shinier the ink film will look. If you are printing on uncoated paper which is relatively rough, the particles will not be able to lay down in a smooth layer and the ink will not look very shiny, but the aluminum particles will still tend to hide the substrate.

If you don’t use metallic gold ink, you should use opaque pigments, and the easiest way to do this is to start with opaque white ink and add whatever other colors you need to make the gold color you want. The more opaque white ink you use in the formulation, and the more ink you lay down when you print, the more opaque the printed ink will be. To get the opacity you want, you may have to give the job two “hits.” In other words, you may have to print one layer of ink, and then go back and print another layer on top of the first. Just be sure you push the sheets up tight to the gauge pins so you can get exact register on the second “hit.” If you do this, you should probably try it with a few sheets first to be sure the second layer transfers and adheres to the first layer OK. You can experiment with whether this works better when the inks are still wet, or whether they are dry. If you wait at least until the first layer of ink gets tacky, then the increased tack of the first layer should pull the less tacky ink off the type (or plate), and onto the substrate.

Some inks can have wax in them which “blooms” to the surface when the ink dries. The purpose of the waxy film on top of the ink film is to give the inks more rub resistance, because whatever rubs on the printed piece will rub on the wax film instead of on the ink film below. If you have this type of ink, the second “hit” may not adhere to the first if you wait until the first layer is completely dry.

What you don’t want to do is use something like process yellow, (or many off-the-shelf colored inks for that matter), because they are formulated to be transparent. With these inks, you are basically printing a colored filter on the substrate. White light from a light source will go through the ink film, bounce off the paper and then go back through the ink film to the viewer’s eye. The ink will absorb all the colors of the white light except the color which the ink is, and transmit that color back to the viewer. With this job, if you print a transparent yellow or “gold” colored ink on the magenta substrate, you will probably get some type of red color. In this case, there probably won’t be much contrast between the ink color and the paper color.

One thing I forgot to say is, if you want a shiny metallic gold, the smoother the paper is, the shinier the gold should turn out.

Thanks so much for the advice- would VanSon’s Unipak metallic inks be a good choice?

Offhand, I don’t see why it wouldn’t work. However, to be as sure as you can…..I went on Van Son’s website and they have a technical support section, http://vansonink.com/tech_support.html, and a technical support hotline, 1-800-645-4182. I would call them and tell them what general type of paper you are using (coated, cast coated, bond, cover, etc.), and ask them if it would work OK, especially as far as drying is concerned if you are printing on coated paper. When calling them, I would present yourself as businesslike (“Hello, this is (your name) from (business or press name)” etc.. Also. they are most likely going to assume that you are printing by offset litho, and I would let them think that until you get the information you want. If you tell them you are printing by letterpress at the beginning, there is a slight chance they might say that they can’t make recommendations for letterpress. If they say that the opacity on magenta paper might be questionable, remember that you can generally lay down a thicker ink film than offset, so it should be better with letterpress. The Van Son site says that the Unipak metallic ink has excellent rub resistance, so it probably has wax in it, and because of this, I wouldn’t wait until the ink is completely dry if you plan to give the job two hits. Good luck! Geoffrey

Jobbing this one out to have it foil stamped, would give you what you are looking for, probably.