Being new to heat printing means trying, learning, failing and growing. It is part of the job and every heat printer has gone through the Beginners course of heat printing where it seems so simple, until it’s time to actually heat print and then the questions start. How long do I press this transfer for? What type of transfer do I use? When do I peel the paper away? And one question that you don’t know you’re going to ask until you press for the first time, why is my shirt turning colors after I press it?!
It’s a concern every one of us heat printers had at a point or another. Most likely you were pressing a Red t-shirt, and when the press opened, the Red turned Maroon! A sudden panic comes over you as you think you ruined your shirt.
Since this question arises almost every day, we thought we’d explain what’s happening to your shirt so you don’t fear another ruined shirt.
Everyday t-shirts containing cotton is the most common apparel item you’ll heat print. Cotton, being a natural fiber, contains some moisture. Moisture is naturally in the air, so you’ll find it in fabric fibers too. Cotton fibers will hold the most moisture. When you apply heat to the fabric that contains moisture, the moisture is heated and turned into steam. This is the “smoke” you’re seeing come out of the side of the heat press when you’re pressing. It’s actually steam! As moisture is turned into steam and removed from the fabric, one thing that happens is that the color of your garment is it will darken where the heat press touched it. This change in color will be most noticeable on colors like mid-toned colors like Red, Royal, Purple, and Green. Other colors will have this effect also, but it’s less noticeable.
So is my shirt ruined?
Not at all! You’re probably glad to hear that. Since moisture was in your fabric naturally because of the moisture in the air, it will be naturally returned to your fabric over some time. This will all depend on your climate you’re in. If you’re in a dryer climate, it may take a little longer than if in a humid area. But generally you will start to see color returning back to it’s normal color within 10 minutes of your shirt cooling down.
Discoloration caused by moisture being removed from the fabric during heat printing.
What if the fabric you’re using is Polyester and not cotton? There’s still a mark where the heat press was.
Similar to cotton, polyester will hold some moisture, so a slight change in color will be normal. However, a different problem might be occurring. Instead of the fabric changing colors, your fabric looks shiny. And it’s a shiny rectangle in the shape of your heat press. What is happening is your fabric is “scorching”. The sheen that is created is telling you that the temperature you’re using is too hot for the fabric. Some Polyester is temperature sensitive and therefore, if using a heat transfer that applies at a high temp, you’ll start to melt the fibers. Most likely, this result is permanent or may fade slightly, however the fibers of the fabric have been altered.
The solution for this problem is using a heat transfer that requires a Low Temperature application to prevent the fabric from scorching. For screen printed transfers, use Elasti Prints® screen printed transfers that apply at a low 300 degrees. Or a Digital transfer like Stretch Litho™ that has an application temperature of 275 degrees.
Scorching caused by high temperature application on a temperature sensitive fabric creates a sheen on the fabric that may not fade.
For more information on the Advantages and Disadvantages of Cotton and Polyester Fabric, check out this blog post.
Advantages and Disadvantages of Cotton and Polyester Fabric
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