Polyester printing can make you look bad even if you are taking all of the necessary steps to prevent dye migration. Why? Because your customers are often not following the washing and drying instructions printed on the inside of the shirt. Even if you print with one of the most bleed resistant inks by One Stroke Inks, ignoring this little tag can cause your bright white print to change into a dirty white, pink, or even green print. Screen printers need to do their best to educate their customers on the reasons the tag was sewn or printed in the garment in the first place. The fabric is not going to self destruct. It will, however, be much more likely to have dye migration problems once it has been washed in hot water and dried too hot. This makes you look bad, even though it is not your fault. It can also make us look bad as our ink may not be holding up as well as advertised. Quite simply, we all need the same thing. We need the end user of these polyester shirts, uniforms, bags, etc. to fully understand the WHY behind the tag in the fabric. I would prefer a neon sign over the box of printed polyester t-shirts that glows brightly with the text “Tumble Dry Low”. “Hang Dry” would be sufficient for most of the lightweight polyester as it dries in just minutes anyway. I know this is not an easy thing as you do not get to speak with every parent on every team to warn them about our industry and the nuances involved with polyester printing. However, the more you drive this into your customers ears, the more likely they will stop the problem before it starts. We will always keep innovating the polyester inks. We simply need you to help educate as many of your customers as you can. In the end, it will lead to higher quality prints and better longevity.
Would you want to have an ink that would cure at a significantly lower temperature? You really should want this but the reasons may not be as obvious as you expect. Let me begin by introducing the Smart LC Series to those who are unaware of it. This is an ink for all fabrics (cotton, poly/cotton, nylon, and polyester). If you print it and cure it like any other plastisol, it will act just like any of your other plastisol inks. Performance at these temperatures is fantastic as you would expect from One Stroke Inks. This is a very high opacity, low bleed ink designed to be universal (the only ink series in your shop). Knowing all of this, where does the low temperature come in?
Smart LC Series can cure as low as 260F (standard inks cure at 320-330F). This gives a crafty screen printer a variety of benefits. First, think of the materials that you screen print. Virtually every fabric has a few troubled colors or styles that really do not like the 320F cure temperature of plastisol inks. Fluorescent cotton t-shirts often scorch easily and even change color in spots when facing high heat. Poly/cotton t-shirts often experience dye migration problems. Nylon can shrink or even melt at higher temperatures. 100% polyester may be the biggest problem as it will do all of this, just in more extreme ways. The dye migration and fabric shrinking you will experience is worse. You can add ghosting problems to the color changing problems. Also, if you heat press polyester, you are at risk of leaving a glossy square where the heat press touched the shirt (this is a time for low temperature transfers).
Curing the Smart LC Series at 260F or 270F will rid your shop of every problem described here. The lower temperature keeps all of these fabrics in a much safer range. Other added bonuses that you may not think about include energy cost. Your large dryer (or many large dryers) are now running around 20% cooler. How has your electric or gas bill been treating you lately. Do you run the air conditioner in the shop? If you do, that will also be much less of an energy draw as well. Just a cooler shop in general may make the lives of the screen printers a lot better. A Happier worker is a more productive worker. The poor QC person at the end of the dryer with the constantly burnt fingers will be smiling. That you can count on.
The only argument against using a low temperature ink such as the Smart LC Series goes a little like this: “I don’t want to throw away all of my other inks so I can switch to this ink.” This is not a problem as the Smart LC Series will still work perfectly fine at the higher temperatures. The more inks that get switched to Smart LC, the more jobs you can run the dryers at lower temperatures. No problem. Think it over.
Before explaining how to print a low temperature transfer, I think it best to explain when and why you should use this technique. It began as a method to prevent 100% polyester digital camo shirts from bleeding through white ink. If you have printed the digital camo, you know what I am talking about. One Stroke Inks introduced the OSI Poly Transfer System which included white ink, paper, and adhesive powder to prevent these problems. Once this started to gain traction, many screen printers realized that printing on paper is easier than printing directly on top of most uniforms. If they messed up a print, they simply threw out a piece of paper instead of a $40.00 moisture management uniform. Since it was so simple and easy, it became necessary to use this technique on more fabrics with more colors. Our customers needed a soft feel with good stretch ability and a less glossy appearance. Bravo Flex Series became the go to ink for non-sublimated low temperature transfers as it fits the role very well. Now screen printers have the ease of printing on cold peel transfer paper and heat pressing onto uniforms, t-shirts, hats, bags, and jackets. It allowed them to print difficult locations without slowing production.
With that information out of the way, here is step-by-step instructions for low temperature transfers:
*You will require Bravo Flex Series inks, T-75 cold peel transfer paper, and OSI Poly Transfer Powder.
1. Expose an 86 or 110 monofilament screen with the art work in reverse. It must be a mirror image as it will eventually be flipped over to heat press the garment.
2. Run your cold peel paper through the dryer to pre-shrink it and to remove any excess moisture. Moisture will cause problems later as you powder the print.
3. If you only have t-shirt platens, apply just a little bit of mist adhesive. You do not want it too sticky as it will transfer to the back of the paper. This can cause storage problems as well as get the adhesive on your heat press. If you want to avoid all of this, order a vacuum platen. This is a platen made for paper printing. It has many little holes and sucks the paper down to the platen as opposed to using adhesives.
4. Print the ink on the paper. You get one pull of the squeegee. One pull. This may sound odd to an experienced printer but it is the deal when screen printing on paper.
5. Take the paper off the platen and apply adhesive powder. This can be accomplished many different ways. The simplest way involves a large bin of the powder and simply sprinkling or pouring the adhesive powder over the print. Shake off the excess back into the bin.
6. This is very important. Tap the paper on a table to remove any powder that is attached to the paper. You can also use air if available to blow off the excess powder. Any powder on the paper where there is no ink will leave a residue on the shirt. It will come out but it is time consuming.
7. Send the paper down your conveyor dryer at normal temperatures for curing a cotton t-shirt. 320F – 330F will be perfect when using a thermo label.
8. You are ready to press. If the transfer was specifically for sublimated polyester, 275F for 10 seconds is perfect. Otherwise, try 300F for 10 seconds on most fabrics.
9. Peel cold. If this sounds like a pain, it isn’t. Simply press everything and then come back and peel everything. No time wasted.
10. Stretch it. Wash it. Abuse it. This is a very durable print.
*Please keep in mind that not all inks, powders, and papers can combine to make this system work. We have tested the Bravo Flex and obviously the OSI Poly Transfer System white ink with this paper and powder and it works. We have seen this fail when other combinations have been attempted.
If you have not experienced the “ghosting” phenomenon yet, be very aware of it. This problem seems to come out of nowhere to ruin moisture management uniforms and tees. Ghosting can occur in a couple of different ways. The first is what we call physical ghosting. Physical ghosting is when the dyes in the fabric are damaged by the heat of the plastisol curing process. Is this avoidable? Maybe. It really depends on how much heat is causing the problem. Low and slow is the best rule in these situations. Slow down your conveyor belt and lower the heat so the curing process is not as dangerous to the fabric. The second way ghosting can occur is what we call chemical ghosting. Chemical Ghosting occurs when there is a chemical reaction between the ink and the dyes in the fabric. One Stroke Inks has identified the chemicals involved and has created numerous series of ink to combat this problem. Smart Series is the most popular. When trying to avoid this problem, it is critical to know ahead of time when this may occur. Without knowing the intimate details of how the fabric was dyed and where, you can be proactive by taking extra precaution when screen printing 100% polyester fabrics of the following colors: light gray, gray, charcoal, light blue, royal, vegas gold, natural, tan, and pink. I am sure you have picked up the fact that gray fabric and lighter colors are most of the problem. Always get an extra shirt to test. Another precaution you can take if chemical ghosting exists would be to line the inside of the shirt with a piece of transfer paper or something similar. This will prevent the ghost image from appearing on the other side of the shirt when in the conveyor dryer.
Softer prints are often requested, especially when screen printing on cotton and poly/cotton. How do you achieve this while still having the coverage necessary for black and navy tees? Some printers will attempt water-based inks. These are difficult to work with in warm months and they really do not cover well. Other screen printers will try discharge inks or a discharge base. These are also difficult and provide very unpredictable results. An easier option is Aquasilk ink by One Stroke Inks. This is a plastisol ink and will print and cure just like any other plastisol ink. Unlike other plastisol inks, it will feel very soft once cured. Similar to plastisol inks, the Aquasilk white and colors have very good opacity for screen printing dark fabrics. Stretch ability is also very good with this ink for printing cotton/lycra or cotton/spandex blends. 158 monofilament mesh or finer is recommended to ensure a soft print. If you have too thick of an ink deposit, this ink may feel more rubber-like as opposed to the soft print you desire.
Screen printing 100% polyester can be very difficult if you do not have the best inks. Even with the best inks by One Stroke Inks such as the Bravo Flex and Smart Series, there are a few guidelines you will want to follow to ensure the best results. First, do not over-flash cure your inks. The flash unit can be a big factor when it comes to how much dye migration you experience. Try to limit how many times a print goes through the conveyor dryer. If you are printing the front, back, shoulders, and so on, every time the uniform goes under the heat again you open yourself up to more dye migration. Avoid fine mesh screens. To be successful, you will need a decent ink deposit. Thin prints will simply bleed faster. Finally, make sure the ink is fully cured. Run a thermolabel and see that it is indicating 320F. An under-cured print will lead to more bleeding. I know the old school approach was to cure at a lower temperature and keep the heat to an absolute minimum. However, if the print does not get fully cured, it is much more likely to have dye migration problems in the short term and long term.
With the 222 Series from One Stroke Inks, you can screen print untreated 100% nylon without the use of a nylon catalyst. Untreated nylon is nylon without any sort of waterproof or water resistant coating. The 222 Series is unique for more than just its great adhesion, it also tells you when it is cured. The print will be glossy once it is fully cured. If the print comes off the conveyor belt and is not glossy, it is simply not fully cured and you should send it back through your dryer at a higher temperature.
You must be very careful when heat pressing 100% polyester tees and uniforms. If the press is too hot or the pressure too high, you are likely to leave glossy areas on the fabric. You may also experience indented lines on the shirt where the edges of the transfer paper or heat press material meet the fabric. The best option to avoid all of this is to use kraft paper as a cover sheet and limit the time and temperature as much as possible. Heat press material such as Siser Easyweed is applied at a lower temperature than most. Also, new cold peel ink transfers can often press at much lower temperatures.
The OSI Reclaiming Powder is the most economical emulsion reclaiming chemical per gallon once mixed. For the standard solution, mix 2 ounces of reclaiming powder with 1 gallon of water. If you would like a stronger solution, try mixing 1 pound of the powder with 5 gallons of water. This is great for tough-to-remove emulsion.
When ink is drying in the screen during a production run, it is most likely caused by the platens heating up excessively. This is a tricky problem as you may be underbasing with white ink or even two screens of white ink. A cool down station may be necessary cool the print and stop the ink from heating up in the screen. If you want to continue with a very fast production, you can try the Production Series inks by One Stroke Inks. These inks will flash and lose their tack in half the time of normal plastisol ink. This keeps the platens cooler and allows production to keep moving. Production Series can help you on cotton, poly/cotton, nylon, and polyester. If you do not want to change inks, test the flash and get it to the quickest possible flash time that you can without the ink remaining wet or tacky. If the ink drying problem is not related to production and you are simply leaving ink in the screen overnight, simply clean the screens at the end of the day. Most inks will clog the mesh when left for this long. Also, you open your screens up to the risk of excessive hazing problems.