1. Could I print on very delicate or flexible items?
2. What are the easiest materials to pad print?
3. Could I pad print all the way around a cylinder or sphere?
4. What are the most difficult materials to pad print?
5. Could I print on items that are greasy or covered with mold release?
6. Can pad printing machines print on anything?
7. Could I print on painted or coated items?
8. Could I pad print into seamlines, stepped levels, grooves or corrugated textures?
1. Could I print on very delicate or flexible items?
The transfer pad applies some pressure to the part being printed. The object must be supported so that it does not flex or shift during printing. Printing a sheet of paper or thin plastic (flexible) is easy, since it can rest on a flat surface. Printing an eggshell, a delicate wine glass, or a Christmas ornament is more challenging and requires special printing pads and fixture tooling. As we frequently say: when in doubt, consult with us.
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2. What are the easiest materials to pad print?
Thermoplastics such as styrene, acrylic, polycarbonate, vinyl, butyrate and blends of those plastics (such as ABS and PVC), wood, paper and lacquered surfaces are among the "easiest" materials to pad print, meaning that they readily accept popular single-component inks.
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3. Could I pad print all the way around a cylinder or sphere?
Sometimes, yes. In conventional pad printing, the image is normally transferred to the desired object in a straight, downward stamping motion. The laws of physics limit pad printing of a compound curve (sphere) or cylindrical object to 30% (120 degrees) coverage (wrap). There is a variation on standard pad printing, in which the artwork designed to wrap around an object is picked up by the pad as flat art, and then the object is rolled across the surface of the pad. This effectively wraps the artwork around the part. The primary limitation of this method is width--the technique works best with narrow bands or stripes.
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4. What are the most difficult materials to pad print?
Silicone rubber and/or silicone coated surfaces, Teflon, nylon, PP/PE and Santoprene are among the most difficult materials to print. Most of them are designed to resist adhesion, and therefore require special inks and possibly special pre-treatment before printing.
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5. Could I print on items that are greasy or covered with mold release?
No. Substrates need to be free of all surface contaminants in order for the ink to adhere properly. In some cases, the substrate may be cleaned with alcohol.
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6. Can pad printing machines print on anything?
Virtually - which means, "we'd say absolutely, except for these little things..." By its very nature, pad printing requires that the ink stick better to the item to be printed than it does to the pad. Otherwise, the ink will not transfer properly. Ink formulators have come up with some chemicals for this problem, but there is a wealth of materials out there that are specifically designed to resist bonding with anything. This rules out printing on greasy or wet surfaces, Teflon and other "non-stick" substrates (some ink may transfer, but in all likelihood it will flake or rub right off). Being a contact printing method, pad printing applies pressure to the substrate, and this usually forbids pad printing extremely fragile objects. Finally, pad printing inks are affected adversely by extremes of temperature and humidity. Frozen objects and heated objects are not suitable.
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7. Could I print on painted or coated items?
In most cases, yes. As with any pad printing application, testing is paramount. Paints such as lacquer, enamel and powder-coatings are pad printable, as are shellac, urethane and most other clear-coats. Some UV, and hard coatings are not suitable for pad printing due to extremely low surface tension.
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8. Could I pad print into seamlines, stepped levels, grooves or corrugated textures?
The answer to this question is a very guarded "maybe." The success or failure of this will largely rest on the geometry of the part, the textures and details within it. The only way to provide a definite answer is case-by-case, through testing.
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