In simple terms a screen printed heat transfer is simply plastisol ink that is printed on a special “release” paper first and then partially cured in standard T-Shirt dryer, flash unit and even under a partially closed heat transfer press. This paper print is then transferred or applied to a T-Shirt or garment using a heat transfer press. If the transfer is made as a special “hot split” the print on the T-Shirt will have the same feel as a direct screen print. If the transfer is made like the “old” way (let’s call it retro), the final image has a rubbery feel – now often called an “athletic” transfer.
Types of Heat Transfers
Hot Split - This is also known as a “hot peel” transfer. It is the most popular type of transfer because it has a very soft direct screen print feel when applied to the shirt. The term “hot split” is used because after this transfer is applied with a heat press for 10 seconds, the paper is quickly removed while hot and the ink actually splits in half. Part of the ink stays on the shirt and part of the ink stays on the paper. This gives the transfer it’s soft feel (figure 1). I still vividly remember my good friend, Richard Labov, former owner of Union Ink Company calling me back in 1980 to say they had accidentally made a soft feel transfer by playing with the plastisol ink formulation and by accident peeling the paper too soon.
Cold Peel - These are still somewhat popular and are being used mainly for athletic uniforms and when you want to apply Foil to a shirt. In fact if you make a transfer correct you can either hot-split it or you can cold-peel it.
Cold-peel and hot-split transfers look and are made the same way. The only real difference is the paper you use and the heat press application. When you apply a cold-peel you let the transfer cool down for about 30 seconds before you peel the paper off. This leaves all of the ink on the garment and gives the transfer the heavier “rubbery” feeling.
Cold-peels are not as popular for large T-Shirt designs because they are hot to wear and don’t let the shirt “breath.” They also will not wash as well because the top, rubbery, layer of ink may crack and start to wash off the garment. Cold-peels have made a comeback as a “retro” type of imprint.
Puff Transfers - Puff ink is special ink that expands or puffs up when the ink is heated. It is very popular on direct printed shirts and can also be used on transfers. The transfer puff ink is a special ink that puffs up after the heat press is opened.
Why Make a Transfer? - Since printing directly on a garment is so easy, people often wonder why they should go to the trouble of making a heat transfer. It’s a good point, so let’s look at the applications for heat transfers.
Baseball Caps - Heat transfers are great for baseball caps. They produce a very sharp print on both light and dark from caps – especially when printing multi-color prints on a cap. With direct printing it is hard to hold fine lines and detail on the soft surface of the cap. With a transfer the image will always be sharp and clear. And, with the new popularity of the white front “truckers” caps, transfers are perfect! It is also very hard to flash-cure between multiple colors on a cap making transfers the natural imprinting method.
Small Orders - Heat transfers are also perfect for the customer who wants to be able to order small quantities on a regular basis. All you have to do is print up extra transfers on the first order and then hold these in stock. When they want another shirt or two you just pull the transfer from the box and print a shirt! If the order is just a small over-the-heart print you can print a number of images on each sheet.
Event Shirts - If you work fairs, festivals or events then you already know the value of a heat transfer. If the event is not successful, it is much easier to throw away printed paper than it is to take home pre-printed shirts! You can just take your heat transfer press, transfers and blank T-Shirts and print souvenir shirts right on the spot. People can pick out the size and color of shirt and you can charge extra if they want another design on the other side of the shirt.
Stock Designs or Preprinted Shirts - This is where the transfers (especially the Hot Peels) really shine! If you make your own line of T-shirts (called “preprints or stock designs”) for either retail application, mail-order, or small order wholesale business, then this is the way to go. You can make up all the designs on paper and then as the orders come in just match the proper shirt and size to the proper design.