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What is ghosting?

Screen printers struggle to prevent a problem known as ghosting. It simply is very difficult to predict exactly when the problem will occur. Luckily, we have tested enough fabric to know what causes ghosting and how to prevent it. If you give us the chance, we will stop ghosting problems from affecting your production.

What is ghosting? See the picture above. What is that exactly? Ghosting is a term we coined as we had to call it something. Perhaps reverse dye sublimation would be a better name. Dye sublimation is the process of dying polyester fabric. Ghosting is basically the reverse process as some of the dye is leaving the fabric. This is why you may be left with some strange colors. For instance, a navy tee which ghosts may look magenta as the blue has disappeared. The magenta dye was not harmed during the screen printing process so magenta is what you see. Sounds simple, right?

“Why can’t you invent an ink which stops ghosting?” This is a question I hear often.  We already have created an ink (a few actually) to prevent ghosting, but it is not as simple as that. Ghosting has more than one cause. I will explain. Physical ghosting is caused by heat. You may have seen this when decorating a light color of polyester. If the tee is not layed flat on the dryer belt, the folds of the fabric which are closer to the heating element may change color. The heat alone is ghosting the fabric. Screen printers who decorate apparel know there is no way to take heat out of the process. You can certainly limit the heat as I will discuss later in the article. You simply cannot remove it from the process.  Ink needs to flash cure. Ink needs to fully cure. Heat is going to happen.

Chemical ghosting is when the ink formula itself is causing the ghosting. Keep in mind chemical ghosting is most often found when screen printing white ink. Ghosting is not a problem exclusive to white ink but it is far more common in white ink due to a variety of necessary additives. These additives may help white ink cover better on dark fabric, print easier through fine mesh, or prevent dye migration on polyester and polyester blend fabrics. Even a simple black ink is capable of ghosting fabric.

Now that you know what causes ghosting, there is just a little bit more to know. Your ghosting troubles can be a combination of physical and chemical ghosting. One common occurance of this happens while hot stacking. Hot stacking is exactly what it sounds like.  You snatch a garment off the dryer belt and place it on a table. You snatch the next garment and place it directly on top of the previous garment. Both of these garments are hot. The ink is hot. If you are printing the wrong fabric with the wrong ink, you may have a ghost image on the back of every garment. Heat in addition to ink formulation is the most likely ghosting culprit.

OK, give me the magic fix already! Hey, no problem. First thing is first, let’s remove a factor. Get rid of the excessive heat. That’s right! We have low temperature ink for a reason. Ghosting isn’t the only purpose for low temperature ink but it certainly is near the top of the list. ELT Series, ELT-S Series, and Smart Series are the three low temperature inks we currently offer. ELT and ELT-S will cure as low as 250ºF. Smart Series will cure as low as 280ºF. All three offer a nice cushion below the typical 320ºF to 330ºF cure temperature of most plastisol inks. Choose one of these three inks and you will have the ability to remove excessive heat from the ghosting equation.

If you have been keeping up, we need more than just low heat to prevent ghosting problems. Let’s talk chemistry! OK, we are not going to talk chemistry. Why? Well, lets just say we have our secrets. Do we know what causes ghosting? Sure. Are we going to get into the chemical formulations of our inks? Nope. It’s not really our thing to give away our secrets. However, when it comes to our inks we have the safest possible option which is ELT Series. We are highly confident that you will not ghost any fabric with ELT white and colors when kept at a lower temperature (270ºF and below). ELT-S Series and Smart Series are also ghost-free formulas and only slightly behind the ELT Series in this regard, but they really need to be cured at the lower temperature. At high temperatures (280ºF and higher) we get nervous on some of the most ghost-unfriendly fabrics. Cure this ink properly and we have no worries.

Yes, I did say ghost-unfriendly fabrics. No, I do not have a list of problem brands and style numbers. The reason I cannot provide this is not because there are tens of thousands of styles out there. The problem is that all styles are not created equal.  Consider a typical “moisture management” tee. They wholesale for around $3.50 to $4.00 each. If you order a dozen of these tees today, will they be the same as a dozen from a few months ago? Is the fabric from Honduras? El Salvador? China? Who dyes this fabric certainly matters and it changes not only from style to style, but within the style. There is just no way to know what you are printing before you print a few.

Here is the good news…I know many of the common offenders! I have a nice list of colors and fabrics which may lead to easy ghosting. Of course, if you were listening earlier you are already sold on our low temperature inks and you will not have to worry about much. Regardless, here are many of the “problem children” out there which will require a skeptical eye:

  • Light colors of 100% polyester including: charcoal, light gray, silver, light blue, columbia blue, pink, tan, vegas gold, royal blue, all fluorescent colors, and sometimes black (I know, that one surprised me too).
  • Fluorescent poly/cotton tees. All of them. Keep a close eye on these tricky kids.
  • Pale colors of cotton and poly cotton including: ivory, off-white, tan, khaki, light blue, light pink, you get the idea.
  • Stone-washed tees.
  • Pigment-dyed tees.
  • Any tee which states “vintage” in the description.
  • Tri-blend tees. I would like to state colors here but it is sporadic at best.

This list is specific but don’t think for a second we haven’t seen ghosting on the common fabrics such as a black or navy poly/cotton. I trust zero fabrics unless I am printing with low temperature inks. That’s all there is to it. If you read this and you understand the importance of dryer temperature, give One Stroke Inks a call and ask us about our ELT Series inks. This is a universal ink so it can be printed on virtually any fabric. Make the change and this will be the only ink you need to stock.

 


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How To: Low Temperature Transfers

Low temperature transfers are becoming more important as delicate fabrics invade the apparel decoration industry. If you have not experienced any heat-related damage by heat pressing fabrics such as 100% polyester or fluorescent tees, you will. It is unavoidable at the high temperatures required for hot split, hot peel, and cold peel transfers. Luckily, we have developed a method of transfer printing which only requires a 10 second press at 280ºF. This will prevent most heat-related damage. This will also provide better bleed resistance for use on polyester fabrics.

Here’s what you need to get started:

  1. Cold peel transfer paper. We offer the T-105 paper for the job.
  2. ELT Zip Transfer Powder. There is a “fashion” and “performance” version of this powder. A good rule to follow is apply performance powder for bad bleeders and fashion powder for everything else.
  3. Any plastisol ink. Select the ink depending on the fabric. Polyester fabric will require a polyester ink.
  4. Multi-color tranfers will require a vacuum platen. Otherwise, you can make this work on your standard press and platens.
  5. Conveyor dryer.
  6. Thermolabels.
  7. Heat press.

Step 1:  Art work and screens

Your art work should be set up to be “mirror image” as you are screen printing transfers now. It will be backwards until you turn the paper over and heat press it to the fabric. For most ink transfers, we highly recommend 86 count screen mesh. 110 is also very effective. For all other screen mesh counts, you will need to test and see if you can achieve effective coverage, bleed resistance, and release from the paper. Expose the screen with the art work as you always do.

Step 2:  Printing

If you are printing one color art, simply register your screen so the print is near the middle of the transfer paper. Many transfer printers will gang up designs so every pull of the squeegee is actually printing multiple transfers. This will lead to less pulls of the squeegee and less paper use, saving time and money.

One item to forget about is the flash cure unit. It is not required, expected, or even recommended to print, flash, print ink onto transfer paper. Flash curing ink onto paper is a time consuming, paper curling process. This is another reason for the coarse mesh count. Without the ability of flash curing and printing a second layer, ink deposit is critical. If opacity matters, ink deposit matters.

Once you have given the print a flood stroke and a couple of pulls of the squeegee, you are ready to powder the transfer. This must be completed while the print is wet so the powder will adhere to the ink deposit. Everybody has their own method for powdering the print. Some decorators simply pour powder out of a small cup over the print and then they shake off all the excess powder. This is pretty quick and efficient. Others have a small bin and they gently lay the paper face down into the powder. Again, they will have to blow, or tap all of the excess powder off the print and paper.

Important note: Any excess powder left on the paper where it does not belong will leave a clear/white stain on the fabric. This is hard to remove so you want to take great care in preventing the powder from sticking to the paper. One way to help this is to send the transfer paper through the dryer prior to printing. This will remove moisture which tends to be a problem.

Step 3:  Dryer Temperature

Low temperature transfers are just that…transfers that can be heat pressed at a low temperature. However, the ink must be fully cured to the transfer paper with the low temperature adhesive powder applied for this process to work properly. Most plastisol inks are fully cured at 320ºF. This means you must cure the ink to the paper at this 320ºF temperature. We recommend the use of a #5 Thermolabel to ensure 320ºF was met.

Step 4:  Heat Pressing Instructions

Preheat the fabric with a short 2 to 3 second press to remove excess moisture and smooth out any wrinkles. The heat press should be set to 280ºF for 10 seconds, medium pressure. The transfer should be peeled once it has fully cooled down as the paper will not release the ink until then.


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ELT-S Series: Let me convince you.

One Stroke Inks is the innovator of true low temperature screen printing inks. First, we pioneered the ELT Series (ELT = extreme low temperature). This ink put an end to so many heat-related screen printing problems. However, this was only the beginning. We needed ELT-S Series.

What does the “S” stand for? The “S” is for stretch and softness. ELT needed an upgrade to handle compression tees, running pants, and singlets. We invented a special S-Additive to allow for these extreme screen printing situations and incorporated it into the already successful ELT Series formula. Obviously, we did not want to compromise bleed resistance or opacity by adding the S-Additive. We had to make some adjustments and improvements as we wanted this new ink to be an amazing improvement. ELT-S Series was born.

With the history out of the way, why should you be screen printing with ELT-S Series inks? The better question is why not? This ink will cure as low as 250ºF. This low cure temperature will prevent so many heat related screen printing problems. These problems include:

  1. Ghosting.
  2. Dye migration.
  3. Fabric discoloration.
  4. Scorching.
  5. Shrinking.
  6. Melting.

How about some other non-traditional benefits? Think about the incredible energy savings you will pocket by turning your conveyor dryers down so dramatically. In my opinion, the energy savings alone makes ELT and ELT-S our most environmentally friendly inks. Your production team won’t mind either. The amount of heat in your shop will be far less abrasive.

ELT-S Series inks don’t just cure at a lower temperature, they flash cure very quickly. Compared to most inks, the flash time will be about half as long. This provides another set of low temperature benefits in which most other plastisol inks cannot compare:

  1. Longer-lasting platen adhesive.
  2. Prevents shrinking which leads to poor color registration.
  3. Prevents dye migration.
  4. Prevents fabric discoloration so common with fluorescent tees.

We also wanted a plastisol ink to replace silicone ink as it is such a hassle to work with. For those not keeping score, here is a list of reasons you don’t want to screen print with silicone inks. Keep in mind all of these statements are found on the silicone ink technical data sheet or sell sheet.

  1. Silicone ink requires a catalyst.
  2. Silicone ink often requires a retardant to improve on-press life.
  3. Silicone ink has on-press life of up to 6 hours.
  4. Silicone ink is only recommended to add enough ink to the screen for 2 to 3 hours.
  5. Silicone ink is not available in a selection of colors, you must custom mix them.
  6. Silicone ink must be cleaned from the screen immediately as it will cure with time.
  7. Silicone ink is not recommended for automated equipment.
  8. Silicone ink is not recommended for “fuzzy” fabric.

As excited as many screen printers were about silicone ink when they first found out about it, these facts inevitably sent them searching for an easier alternative. This is where ELT-S Series comes in. Here is a list of reasons ELT-S Series is a better choice when compared to silicone ink:

  1. Soft/stretchy feel.
  2. Impressive opacity on dark fabric.
  3. Excellent bleed resistance on polyester.
  4. Universal ink. ELT-S will screen print on virtually any fabric.
  5. No catalyst required unless you are screen printing waterproof nylon or waterproof polyester.
  6. It’s plastisol. ELT-S Series can be left in the screen like any other plastisol ink.
  7. Huge color selection with custom color matching available.

Now that I have compared ELT-S to silicone ink, explained the benefits of a quick flash and a low cure temperature, let me tell you why you are really going to make the change. The fact is, you are tired of worrying about expensive fabric. Whether it is a name brand polyester hoodie or an inexpensive neon yellow tee, you don’t want to order one or two more pieces for a screen printing snafu. You don’t want to set that job up again tomorrow for these few replacements. You really don’t want to replace hundreds or even thousands of $65.00 uniforms due to dye migration that did not exist when they left your shop. All of these problems cost you far too much money to keep using high temperature, often ineffective inks. This is a better way. ELT-S gives you the ability to sleep at night. Nobody knows how the next shirt is going to react to your ink or dryer. ELT-S will always give you the best chance at success. I won’t sit here and tell you there will never be a problem with ELT-S in your shop. However, I will tell you there is not an ink on the planet that can do what this ink can do.

Heat Pressing Polyester


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Heat press damaging polyester shirts.

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.