I’m not going to start this article with the cliché definition of sublimation. It’s eye catching, but not very helpful. I’m going to give you my definition of the process of successfully applying a sublimation transfer to a coated mug:
Apply just enough pressure to make the transfer come into intimate contact with the mug while raising the temperature of the coating to the point it will accept the sublimation dyes.
In the early days of photo mugs, the printers most commonly used were still video dye sublimation printers. These printers used polymer “paper” that received the dyes from ink ribbons. This paper was not porous, and it had a relatively low melting point. Mug coatings were developed which would accept the sublimation dyes just below the melting point of the paper. Mug presses were built so that the mug and transfer could be removed halfway through the pressing cycle to allow the decorator to remove any air pockets that developed between the paper and the mug. The result was an acceptable novelty that wasn’t very dishwasher durable.
Along came inkjet printers and sublimation ink with paper that could withstand higher temperatures and was more pliable and porous. Innovative coaters responded with “harder” coatings that accept dyes at a higher temperature and are more dishwasher and scuff resistant. Mug wraps were introduced that overcame a mug press’ inability to easily accommodate varying diameters of mugs and allowed the decorator to more consistently transfer all the way to the bottom of a mug and get closer to the handle.
Why the history lesson? Many distributors of sublimation products are stuck in the old days or enjoy the profits from expensive mug presses. I’m here to show you how to use today’s tools to make you a better mug decorator and maximize your profits.
There are many combinations of graphics programs, printers and inks, so I’m going to focus on how to properly apply the transfer.
The Right Mug
The success of your transfer is largely dependent on the coated mug. There are a half dozen or so manufacturers of coated mugs, and not all mugs are created equally. Here are some guidelines to help you select the best.
Find the whitest mug available. There is no white dye available for sublimation printing. The whiter the mug, the more accurate color reproduction you will get and the better contrast or “pop”. This is why the premium photo printing paper is so white.
Check the taper at the bottom of the mug. All mugs are tapered at the bottom to allow it to easily slip out of the mold, but an excessive taper will cause wrinkling of the transfer paper and a ruined finished product.
Make sure the mug is “hard coated”. There are still mugs out in the marketplace that will fade after a dozen or so dishwashing cycles. A hard-coated mug will take longer to transfer, but the added dishwasher durability is well worth a few more minutes of production time. Try to scratch the coating with your fingernail. If you can mar the finish, it likely won’t hold up under repeated dishwashing cycles.
Look very closely at the gloss of the mug. A super bright, glass smooth glossy finish is often an indication of a very thin coating. You will get a good transfer if not overheated, but it will not have the dishwasher durability of a heavier coating. A mug with a thick enough coating to properly hold the dye will have a slightly cloudy and wavy finish.
Examine the surface of the mug. The coating in the image area should be free of any debris stuck in the coating or deep pinholes in the ceramic. Any small indentations should be completely filled with coating.
Look at the interior of the mug to make sure that there isn’t excessive overspray of coating where the coffee will likely reach. Most coatings will also accept the dye in coffee and a mug that has coating on the inside will look dirty after a few uses.
The Right Mug Wrap
There are several different types of mug wraps on the marketplace. Some of the wraps are advertised as “Quick Wraps” and use some type of buckle, clamp or rings to fasten the wrap. These wraps don’t accommodate varying diameters of mugs accurately. The best wraps are those that were designed to be tightened with a drill with a slip clutch. You’ll hear lots of advice on how to best tighten these wraps, but the absolute best way is to use the Ryobi 3/8 inch VSR Clutch Driver set at clutch setting #4. It’s available at Home Depot for $40. The model number is D46CK and Home Depot’s store SKU is 839977. Using this drill at this setting will ensure that you are applying optimum pressure regardless of the mug diameter.
Take care not to over-tighten the wraps, as it will shorten their life, and periodically lubricate the threads with Teflon or high-temperature lithium grease. Don’t set your oven above 400 degrees, as the adhesive used to laminate the wraps will degrade above that temperature.
The Right Transfer
The mug transfer should be sized so that the paper covers the mug from top to bottom and handle to handle. If you leave areas exposed, you may experience transfer of the dyes where you don’t expect it. This phenomenon, called blowout, is hazy blotches of unwanted color that appear after you remove the wrap and transfer. If you want to conserve your transfer paper, you can make a cover sheet of copy paper that has been trimmed to a size that will completely cover the mug and tape it on top of your smaller transfer. Your transfer should not be more than about 1/4” taller than the mug or it may introduce wrinkles.
Take a moment to inspect the mug prior to taping the transfer. Ceramic mugs are susceptible to static electricity, and dust may be on the surface. Wipe it clean with a lint-free cloth and check for any imperfections in the coating. A few seconds of inspection may save you the added expense of ink and labor applied to a mug that won’t properly accept the dye.
Tape the transfer to the mug with a single piece of tape applied horizontally on each end of the transfer and centered vertically. If you tape off-center or apply the tape vertically, the transfer may not conform to the mug properly. If the mug has a known excessive taper, moving the tape a small amount in the direction of greater diameter can remedy wrinkling problems. Use your fingers to stretch the paper as tightly around the mug as possible. If the transfer is not snug to the mug, it may shift or wrinkle when you apply the wrap.
Center the wrap around the mug and taped transfer, leaving an equal amount of distance from the ends of the wrap to either side of the handle. Use caution that the wrap doesn’t touch either side of the handle while tightening, or the wrap will have uneven tension around its circumference. Uneven tension causes uneven pressure against the transfer and mug, which can result in unwanted dark and light areas throughout the image area.
The Right Heat
Convection ovens are the best choice for applying heat to your wrapped mug. The baking space is evenly heated, and the moving air conducts to the mug easier, which shortens transfer times. Choose one that has plenty of height to accommodate various shapes of mugs and allows some distance away from the heating elements. My favorite of the small ovens is the Hamilton Beach 31197R. It’s widely available online for about $95 and accommodates four mugs at a time. The small convection ovens don’t have quite the horsepower as large commercial ovens, so my rule of thumb is to find the perfect time and temperature for one mug and then add an additional minute for each additional mug you wish to bake at the same time.
Your mug supplier should be able to give you a ballpark time and temperature to start off. Each oven behaves a little differently from the next, so it’s up to you to dial yours in. Place the mug in the oven upside down, and evenly space the mugs if transferring more than one at a time. Start at the suggested time and temperature and then look closely at your first result—I use a magnifying glass or jeweler’s loupe. If the image seems too light and the transfer you pulled off appears to have most of the ink still on it, increase your time in one-minute intervals. If you exceed three minutes beyond your supplier’s recommendation to get good results, increase the temperature about 20 degrees and start back at the recommended time.
If the image looks fuzzy, has shifted colors, the transfer paper is scorched, and has most of the ink gone, you are baking for too long, or too hot. Decrease the time in one-minute intervals, and if you have to cut back three minutes or more, decrease the temperature 20 degrees and start back at the recommended time.
Ideally you want to push right up to the edge of fuzzy. This is where the magnifying glass comes in handy—check your image for sideways migration of dye. It’s easiest to see on fine, dark lettering. When you begin to see the dye migration, back your time off thirty seconds. This ensures that you are reaching a maximum depth into the coating, and your finished mugs will be as dishwasher durable as possible. It’s tempting to use a higher than recommended temperature for a shorter time, and your image may look great, but all the dye is on the surface of the coating and will be very vulnerable to the heat and chemicals of a dishwasher.
The Right Way To Cool
I hear many suppliers telling customers to quench the unwrapped mug immediately in water. This practice invites disaster down the road. Back in the day of softer coatings and lower transfer temperatures, I was guilty of this bad habit. The softer coatings allowed the dyes to continue sublimating (into the air) if the temperature wasn’t lowered rapidly. The solution was to dunk them in warm water to stop the process. In my defense, I would “ring” the quenched mugs with a metal object to check to see if the mug body was intact. A cracked body makes a muffled thunk rather than a nice ring.
As coatings got harder and transfer temperatures got higher, I could hear occasional pings and pops when the mugs were quenched and found a much higher percentage of thunks when ringing the mugs. I studied the mugs closer (out comes that magnifying glass again) and found that almost every quenched mug (even those that ring true) had hairline fractures in the glaze. The cracks can widen over time, and the cracks on the inside of the mug will stain over time and look like spider webs. The cracks are hardest to see on the outside of the mug because the coating bridges the cracks. If you don’t believe me, test it yourself. Quench a 400 degree mug in room temperature water. Pour some shoe dye inside the mug and use a cloth to rub the dye all around the inside of the mug, or better yet, let an inch or so of dye sit in the bottom of the mug overnight.
The right way to cool a mug is to use a fan. The fastest way to cool a mug with a fan is to angle the fan down at about a forty-five degree angle. The air will rush by the sides and displace the air inside the mug, cooling it to the touch in just a few minutes.
There you have it—the right way to transfer a mug. And when you have problems, there is a right way to troubleshoot.
Walk away from the problem for a few minutes.
Look carefully at what may have changed.
If it’s a color issue, too much or too little, look at the transfer paper to see how much ink is left and if the color of the paper itself looks normal. Oven elements do go bad, and it is possible to forget to set the oven to convection mode.
If it’s a wrinkle issue, check the mug for excessive taper and make sure you sized and taped the transfer properly.
If it’s an absence of color somewhere, check the sides of the mug with a straight edge for excessive dip and make sure the mug wrap didn’t hit one side of the handle while tightening.
If one side of the mug is darker than the other, make sure you left adequate space between the mugs for air flow.
If you quenched the mugs and your customer complains of stains or the handle falling off, I told you so.
If the solution doesn’t come quickly, contact your supplier before ruining a bunch of mugs. Few of us use the same language for all scenarios, so take a few digital pictures to best communicate your problem. Your supplier should have the experience to get you back on track; if they don’t, contact and send the pictures to another supplier.