Pressing Concerns How to successfully image dye-sub ceramic tiles. By Cary Green The art of creating beautiful, personalized dye-sub ceramic tile products depends on using the right equipment and mastering some basic techniques. If you re new to this, I m going to share some of what I ve learned over the last 14 years to give you a head start. Old hands at dye-subbing tiles will find this a useful review of the basics, and may learn a new trick or two. First, the equipment: a heat press capable of pressing at least 1/2 thick material, dye-sub ceramic tiles, dye-sub printed transfers, Nomex felt pads and a Teflon sheet. Heat-resistant gloves are also recommended. Heat Press Selection It is imperative to use a heat press that is capable of uniformly pressing tiles and other thick products. Several manufacturers offer heat presses suitable for this purpose. Photo 1 We use a swing-away press for small, quick jobs, and a shuttle press for large murals. Newer clamshell presses may accommodate thick tile products, but older-model clamshell presses were only designed to handle T-shirts. While they may be able to press one small tile at a time, they don t reliably deliver uniform pressure, especially across several tiles at once. This is important when you are in production and trying to get consistent color. Ceramic Tile Selection The most commonly used dye-sub ceramic tiles are made in the U.S.A. or Southeast Asia. We will refer to them here as U.S. tiles or China tiles. U.S. tiles may be manufactured in the U.S.A. or Mexico. There are only a few dye-sub coating plants in the U.S. that coat U.S. tiles for the dye sub market. Most sell direct as well as through dealers. China tiles may come from China, Sri Lanka, Taiwan or other countries in Southeast Asia, and may be coated in the U.S. or overseas. U.S. tile is approximately 1/4 thick and is usually available in a gloss, satin or matte finish. The decision to pick one finish over another is best guided by personal preference. The two most popular sizes of U.S. tile, 4.25 and 6, have built-in spacers on the sides [See Photo 1]. Spacers facilitate grouting and save the tile installer time and money. Other sizes of U.S. tiles do not usually have spacers. China tiles tend to be about 1/16 thinner than U.S. tiles. They are usually only available in gloss finish, and they do not have spacers. The presence or absence of spacers is important if you are fitting the tile to a frame or box lid. A China tile may be too loose, and may sit too low in a frame or box designed for U.S. tile. Conversely, a U.S. tile may be too big, or may not lay flush with a frame or box designed for China tile. It is important to note that ceramic tile is manufactured for the construction industry, not the printing industry. Some variances, such as tiny pinholes, dust or voids in the glaze are normal, but most are so minor, they are overcome by the image. Tip: Check with your supplier to make sure the tile you plan to use will fit the product or accessory you have chosen. Printed Transfers Successful dye sub tile pressing starts with successful printing. To ensure optimal, consistent color output, keep your dye sub printer in good working order, including routine maintenance. Minimally, you should perform a head clean and nozzle check at the start of each 34 THE SUBLIMATION REPORT Spring 2013 a-e-mag.com printwearmag.com
day s production, with a second check in the middle of a long run. Printed dye sublimation transfers should be kept in a clean, dry place away from direct heat sources. Avoid using spray cans or bottles around printed transfers. Mist or overspray can travel several feet, staining your transfer. Even a sneeze can travel as far as 12 feet. You might not even notice that a transfer is stained until it is pressed. Handle printed dye-sub transfers carefully. Make sure your hands and fingers are clean, completely dry and free of any sweat, lotions, oils, powders or perfumes. It should go without saying that your production room should be clean, safe, dry, free of dust and neither too hot nor too cold. Make sure you have adequate space for air to flow around your heat press, as well as a clean, flat table on which to cool the tiles, and enough room to move quickly between the press and your cooling station. Tip: Keep all your supplies, including printed transfers and Nomex felt pads, clean and dry. Use Info # 918 The Process The dye-sub imaging process has a sweet spot an optimal combination of temperature, pressure and time. If your temperature, pressure and/or time are too low, you may end up with a faint image. The reverse is also true. If you press too hot or for too long, you can burn out your image, resulting in loss of color, diminished detail, and leaving edges of fonts and lines fuzzy. Temperature Ceramic tiles are commonly pressed at 400 o F. a-e-mag.com printwearmag.com THE SUBLIMATION REPORT Spring 2013 35
Press Tile Face-Down Ten years ago, most dye-subbers pressed tile face-up, wrapping the printed transfer around the tile, taping it to the back, and covering it with a thermal rubber mat. While the faceup method produced good results, it was time-consuming, cumbersome and required more supplies. Today, most dye-subbers press ceramic tile face-down through the bottom of the tile. This method is faster, easier and more accurate than pressing face-up. You can quickly register the image in a glance; there is no need to wrap transfer paper around the tile or fuss with heat tape, and you don t need an expensive rubber mat. Tip: Do not stack ceramic tiles. Stacking tiles will scratch the coated surface and ruin your product. If you must stack tiles, use foam slip sheets between each tile. Photo 2 Photo 3 To Press Ceramic Tile Face-Down 1. Cover your press bed with a Teflon sheet. 2. Place the heat-resistant felt pad insulation (Nomex) on your press bed. Nomex is available in different thicknesses from about 1/8 to 1/2. For ceramic tile, we recommend using a minimum 1/4 thick layer of felt. You can use one 1/4 pad or two 1/8 pads. The felt pad facilitates full contact of the transfer across the surface of the tile, and over the edges or shoulders, for a nice bleed. Nomex pads are durable and usually last a long time. 3. Place your printed dye-sub transfer face-up on the felt pad. 4. Place your ceramic tile face-down on the transfer. You should be able to see 1/8 or so of the printed image all the way around the edge of the tile [See Photo 2]. Most ceramic tiles have a pattern or grid on the back. The grid aids adhesion to the cement or grout during installation. Different tile manufacturers employ different grids. Most grid patterns are not a problem. However, some grids are so deep, they 36 THE SUBLIMATION REPORT Spring 2013 a-e-mag.com printwearmag.com
hinder heat absorption, leaving a large void in your imaged tile [See Photo 3]. This is particularly true on certain 4.25, 6 and 6"x8 U.S. tiles. Do not try to reduce a grid void by increasing the dwell time or temperature. That could result in a loss of image color and detail. Instead, we recommend placing a penny (a dime with pneumatic presses) in the center of the grid [See Photo 4]. This will amplify heat to the center of the tile so the image develops evenly. Tip: The penny trick only applies to tiles that have a grid pattern that allows a penny to rest comfortably between the ridges. If you place a coin on the back of any other tile, the tile could break when you press it. 5. If you wish, you may put another Teflon sheet or plain piece of copy paper Photo 4 Use Info # 919 a-e-mag.com printwearmag.com THE SUBLIMATION REPORT Spring 2013 37
Photo 5 over the back of the tile to keep the heat platen clean and scratch-free. This will not affect dwell time. Tip: Do not put a rubber mat over the back of the tile. Doing so will needlessly increase your dwell time and could result in a loss of color and sharpness. 6. Set your pressure. The correct pressure for ceramic tile should be mediumfirm. To get that, put your press in the down position on a tile. Tighten the tension knob until you can t easily turn it any more. Then lift your press and add an extra 1/8 turn of the knob. You now have medium-firm pressure. If you re using a pneumatic press, the pressure setting for most ceramic tiles should be about 60 pounds per square inch (PSI). On a manual heat press, check your pressure during the first two minutes of pressing. The rubber press bed softens in the heat, and your felt pad gets compressed. If the press feels loose, turn the knob an additional 1/4 turn to firm it up again. You should only need to make this adjustment once in the beginning of your production run. 7. Set your dwell time. Most dye-sub suppliers sell ceramic tiles, but they may carry brands with different coatings, and recommended settings may vary. Always check your supplier s directions first. Suggested Dwell Times For Ceramic Tile Size Dwell Time 2 x 2 4 min 3 x 6 5 min 4.25 x 4.25 6 min 6 x 6 6-6.5 min 6 x 8 7 min 8 x 8 8 min 8 x 10 8.5-9 min 12 x 12 10 min Suggested times are based on U.S. tile. Deduct 30 seconds to one minute for China tile. If you have trouble achieving full-color strength and clarity with your supplier s directions or with the chart above, you might need to fine tune your dwell time to match your equipment. See Fine- Tuning Your Dwell Time, which is further down in this article. Tip: Different types or sizes of ceramic tiles may require different dwell times. Do not press different sizes of tile at the same time. 8. Carefully lift the press and turn the tile over. 9. Check the color and detail of your tile. If the image is good, keep pressing. If not, you may need to fine tune your dwell time. * If your printed tile is too light, and there is still ink on the transfer paper, you may not have pressed long enough. Increase your dwell time in 30-second increments until you get rich colors. * If your printed tile is too light, but the ink on the transfer paper is spent, and image details are indistinct or fuzzy, you may have insufficient pressure or pressed too long. First, check to make sure you have medium-firm pressure and try again. If the image is still too light and edges are blurry, reduce your dwell time in 30-second increments until you can see that the edges of fonts are distinct. * A light haze on the surface of your tile is usually an indication that the coating is a soft formulation. You may be able to mitigate the haze by reducing your temperature to between 385-395 o F. * Paper sticking to your tile is almost always an indication that the coating is under-cured. In some cases, you might be able to post-cure the tile yourself. For best results, stop pressing and contact your supplier for help. * White lines or spots on an imaged tile [See Photo 5] can be caused by many things a clogged print head; poor registration; uneven pressure, dust, hair or other particles that got lodged between the transfer paper and tile during pressing; fingerprints on the printed transfer; over spray from a can or spray bottle; as well as a problem with the raw tile. Save the used transfer paper, the printed tile and 1-2 unused transfers, and call your supplier for help. 10. Place the hot tile face-up on a table or cookie rack. The ideal way to cool ceramic tile is with a fan blowing across the surface. Never dip tiles in water to cool. Do not stack ceramic tiles. Stacking 38 THE SUBLIMATION REPORT Spring 2013 a-e-mag.com printwearmag.com
tiles, especially hot, will scratch your tile. Tip: After ceramic tiles are pressed and cooled, spray and wipe Pledge furniture polish onto the tile for additional scratchand scuff-resistance. How Many Tiles Can Be Pressed At Once? That depends on the size of your heat press. I recommend leaving at least 1/2 between tiles, and at least 1/2 between the edge of the platen and the edge of the tiles, in order to get sufficient pressure along all four edges of each tile. For best results, cut the transfers apart before arranging them on the press bed. A large, continuous sheet of transfer paper acts like a board, reducing pressure along the edges of each tile, and resulting in faint edges or an incomplete bleed. If you are pressing a bed of tiles at one time, add an extra minute to the single tile dwell time. If you are making a mural, remember to mark the backs of the tiles so your client knows how to put them together. We use an alpha-numeric system. Columns are labeled with letters, rows with numbers. When you ve finished pressing a mural, assemble the tiles face-up on a table or floor to make sure the image is complete and the color is uniform before you ship it to the customer. Tip: If you are pressing multiple tiles at one time, cut the transfers apart before arranging them on the press bed. Fine-Tuning Your Dwell Time Print several transfers using an image that is 1/2 the size of your tile. The image should employ CMYK colors and possess a paragraph of text, such as black on white, and white reversed out in a black box. Print one-half of one tile with this image. Allow the tile to cool and check the image, particularly the text. Is the image and text bright and crisp? If the white text is filling in with the black background [See Photo 6], you have pressed too long. Reduce your dwell time by 30 seconds. Now press the same image Photo 6 on the other half of the same tile. Allow the tile to cool and check the text again. Continue reducing dwell time in 30-second intervals until the white text is clear and the text edges are sharp. Always document your results. Decorating ceramic tile with dye sublimation can be easy, profitable and fun when you use the right equipment and follow some simple techniques. Now, go press tiles and make some money! Cary Green is president of LRi/Laser Reproductions, Inc. in Skokie, Ill., a leading supplier of dye-sub inks, systems, supplies, blank imprintables, dye sublimation equipment, and custom coating services. SR a-e-mag.com printwearmag.com THE SUBLIMATION REPORT Spring 2013 39