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What is ghosting?

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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.

 

Author: Robb Mears

Director of Product Development with One Stroke Inks.

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