After several weeks of trial and error I think I've made a real advance in producing decals. There are a ton of variables that had to be tested but in the end it was probably more serendipity than anything else. Here's what I came up with....
The Photo EZ emulsion film seems to work the best of the different brands I tried. The High-Res works great for this application.
I used transparencies for ink jet printers. I had to print the same image twice on the same transparency twice to make it dark enough to work properly with the emulsion.
I tried various artificial lighting but sunlight works the best (and cheapest). Circuit Bridge has a list of suggested exposure times. I found they were too short. Rather than the 20 or seconds recommended I left the film exposed for almost a minute. Anything less left the film underexposed which means the entire piece of film disolves in the developer (clear water) and washes down the drain.
Between the double printed image and the exposure to sunlight I was able to produce a screen where even the smallest lettering was clear and usable.
Leave the film in the water for at least 15 minutes. Rinse it with clear water. I use a drop or so of Dawn dish detergent and gently rub the film with my fingers to loosen up the unexposed emulsion.
Once the screen is rinsed leave it dry in the open air and light....
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| Latest Screen |
The screen I created ended up being a negative which is not what's needed. You should be able to read the text in the normal fashion.
I use screen printers ink. It is very thick so it doesn't flow easily. I use it at this consistancy with no thinner of any kind
The screen should be placed with the emulsion side up. I fasten one edge down with some scotch tape and make sure the screen is flat before taping down the opposite edge. I use a brush to pile some of the ink at the edge of the screen and then I use a plastic or rubber squegee to spread the ink. I apply slight pressure and holding the squeegee at an angle I move slowly across the screen...
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| Best Yet |
This is the first print where the lettering around the logo was visible. It's also possible to read the small class numbers and reporting marks. The sample shown here is actually meant to be used with the CNJ diesel set I'm creating, so it will eventually require colors. For freight cars and such the white lettering is just fine. I was able to reproduce these results on clear decal paper. I forgot, however, to spray a coat of clear to seal the decal and the ink washed off. The label says the ink is permanent on metal paper, etc. Maybe I didn't let it dry long enough. I made another decal and sprayed it with a clearcoat. I'm still waiting for it to dry. I tried to get an image and had to play with the contrast a bit so the white showed better against the white background. This is a clear decal with a white paper backing...
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| Actual Decal |
At this point I'm pretty confident that useful decals can be made with this process. The costs of materials is pretty low. All that is required is Photo EZ sheets, screen printing ink and clear decal paper. There may even be a way to print directly on the nodel itself. Haven't tried it yet.
Another observation I have comes from working on the CNJ units. The test unit I did came out great. The "real" units did not...
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| Test Unit Left, Ruined Unit Right |
The reason seems to be the masking tape I used. I switched to Testor's tape and that was a mistake. I should have stayed with the Tamiya tape. The Testor's is too stiff and will not conform properly to the contours of the model. As a result there is quite a bit of overspray. This is not an issue with Tamiya...
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| Tamiya: Good |
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| Testor's: Bad |
I tried to salvage the models. Stripping them again might cause problems. The shells, especially the Baldwins, are liable to break. So I masked off the blue and resprayed the orange. After that dried I masked off the orange and shot another layer of blue. They came out much better. Not perfect, but passable...
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| Rescued CNJ Units |
Since I believe I'm now able to make the decals for these units, I tried to tint the white ink I have to make the orange and blue. Didn't like the way it came out so I'm ordering two small jars of ink in the appropiate colors. A four ounce jar cost about five bucks.
Regards,
Frank Musick
Building a dream layout on a nightmare budget
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The Average Eastern Railroad
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