Silicone ink is designed to be used for both pad printing and screen printing. At this point, you’re probably wondering what the difference is between standard pad printing ink and silicone ink. The article the idiosyncrasies of printing silicone products explains how the process differs from printing with solvent-based ink in terms of pad size, pad cleaning, and depth of plate etch.
Silicone is a unique substrate, and without getting into all the complicated chemistry behind it, UV curable ink and regular solvent-based inks will not adhere to silicone, so a specialty ink must be used. The only ink that can stick to silicone is a silicone-based ink. Unlike some solvent-based inks, silicone ink requires heat to cure. Inkcups offers the SI Series or the SI-HD Series, both as great options for decorating silicone products. The SI-HD ink was reformulated for superior opacity compared to other inks on the market. Both are designed for durability and have a high resistance to scratching, bending and stretching. These properties give both series flexibility like no other.
The Silicone Ink Series can be both pad printed and screen printed. No matter which method you choose, heat curing is needed to completely dry the ink.
Pad printing silicone ink is completed like any other pad printing job. The operator will mix the ink with a specific percentage of hardener and solvent. They will then fill the ink cup with the ink mixture. After securing it onto the pad printer, the operator is ready to start printing. Since silicone needs to be cured after printing, only one color can be pad printed at a time. If your artwork requires two colors, you will have to cure your product after each color is printed. Additionally, ensuring the registration is exact is also important with a two-color print. Since silicone requires heat to dry, the ink will remain wet until it is properly cured. In order to print high-quality images, the pad must be cleaned every few prints since the silicone ink will start to stick to the silicone pad. The article when to change a pad printing pad includes tell-tale signs it’s time to purchase new pads, as well as tips and recommendations by the experts at Inkcups. Any discoloration or “fuzzy” looking areas are definitive signs it’s time to replace the pad. The amount of time and temperature required for curing depends on the ink you are using. For example, the SI-HD Series by Inkcups requires drying in a 200°F (93°C) oven for 4-7 minutes. After, the item is ready to be presented.
Pad printing supplies include the printing machine as well as pads, plates, inks, and ink cups, which are small and easy to store. Pad printing requires very little ink. For example, a 2” x 2” square costs about $.03 in ink. As for printing plates, the recommendation is to use laser plates over polymer plates as it will yield fewer streaks in the artwork. The artwork should also have a shallower etch so that the ink does not splash when laid onto the silicone item. This is important to note. If the etch is too deep, the silicone ink will spread, compromising the print quality. The main goal of pad printing is to have just the right amount of ink so that it is all released on the substrate and there is no build up on the pad. As you may have guessed, harder pads work better for releasing ink onto silicone. We recommend a medium to hard pad with a durometer of 60-70. If you are unsure what type of plates, printer, inks, or pads to use for printing on your products, don’t worry – contact us, that’s why we’re here.
Screen printing requires the operator to use a mesh screen that is coated with an emulsion. A stencil blocks pieces of the screen in order to develop the graphics. The screen mesh is stretched over a wooden or metal frame. Once the screen is complete, the operator pours the ink onto the screen and uses a squeegee to press the ink through the screen. The ink will only be applied where the stencil is open. More ink can be used for a bold print –but there is still a risk of overprinting depending on the size of the mesh. The boldness of the design depends on how coarse the screen mesh is. For example, a 150 mesh should be used for bolder, larger graphics with less detail. A 305 or 310 mesh is tighter and standard for printing fine lines and small fonts, especially cursive writing. Templates can be created which allows for uniform designs and greater productivity. Extra caution must be taken when running high volume production at very high speeds because the friction over the screen may heat up the ink, causing it to get thicker and stuck in the screen. If this happens, the squeegee speed should be reduced in order to reduce friction. Too much pressure could also cause the screen to break. Make sure to always have extra screen wash solution and screens available just in case you run into these problems!
When comparing the two types of printing for silicone items, there are a few important factors to keep in mind. First off, pad printing costs less, requires less production space, and wastes less ink. The main reason to choose screen printing is if you need to print 360° around a cylindrical object. When it comes to pad printing, designs should be less than 90° around the object. When using multiple colors for both methods of printing, the ink must be cured before adding another color. Pad printing is ideal for printing small logos or designs in one color. The more colors used, the longer the process will take. In order to print multiple colors with screen printing, you either need to clean the screen between colors or use multiple screens. Screens are much bigger than plates, so more production space is necessary. This also means you will need a large sink or a hose with an area for washing stencils and screens. This process may need to be outsourced because it requires additional space and time which may not be feasible at your location. Additionally, because the ink must be mixed with a hardener before use, extra ink cannot be reused and must be discarded. When pad printing, extra ink can be stored for 24 hours in the sealed ink cup with no damage to ink quality. In the long run, this makes the screen-printing process more expensive than pad printing, not to mention the negative environmental impacts of extra waste.
When it comes to deciding whether to pad print or screen print on silicone, the shape of the object and the number of colors used must be considered. Although one process is not always better than the other, in terms of storing materials, setting up, and cleaning up the production space, the pad printing process is much simpler. Are you ready to start printing on silicone? Here are the top 5 applications for printing on silicone, with silicone ink.
If you are not sure if your product is actually made out of 100% silicone watch the video: Silicone Printing: How to Test if your Product is actually Silicone.
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