Why would you want to use a screen printed transfer that uses extra materials, extra labor, and more equipment when you can print directly onto the garment? There are several situations where transfer are more efficient, economical, and profitable than direct printing.
For example, if you have a once a year event that you print for but you have no way of knowing how many shirts will be sold. If you print too few shirts, you will limit your sales. If you print too many shirts, you take an expensive loss. However, if you print the design on transfer paper, you can take the transfers, heat press, and blank shirts to the event and press the shirts as ordered. If you have any transfer left over, you can throw them away and not be losing the money that you would if you were throwing printed shirts away.
If you do the same design over and over for a certain customer and they only get a small number of shirts everytime. It is cheaper to go ahead and print enough transfers to last a while, than it is to set up the job on the press and run a dozen or two shirts at a time. You save a lot of time and labor by using transfers for this customer.
Equipment Needed for Transfers
Transfer paper, Transfer powder( if necessary), Heat Press, Conveyor Dryer, Flash Unit (if doing multiple color design)
Types of Transfers
There are two most common types of transfers, Hot Split and Cold Peel. The main difference in the two are the way they are applied. When applying hot split transfers, the transfer paper is removed immediately after pressing the garment. This method will give you a softer feel but will take away the opacity of the print, especially on dark garment.
cold peel, the paper is not removed until the ink and garment have
cooled off. This method will allow all of the ink to adhere to the
garment, making it a more stiff, opaque, glossy look.
In transfer printing, fine detail causes trouble because it is hard to print enough ink and control the temperature of the ink closely enough to insure that the fine lines will adhere to the t-shirt. Lines should be no thinner than 1/16th of an inch and half tone dots should be no finer than .33-.38 millimeters. If you have to print fine lines or small half tones, you should always print an underbase over the entire design, making it the last color down. The underbase will adhere to the garment and the other colors in the transfer, including the fine detail.
Large areas of solid colors may cause problems because they require a very even layer of ink, very evenly gelled. Any imperfections in the thickness of the ink layer or degree of gelling of the transfer may result in an uneven thickness of ink transferred to the t-shirt and an obviously defective design.
Avoid Trapping Colors
Trapping colors creates different thicknesses of ink on the transfers, making is complicate the gelling process, and when using a hot split, it may cause the wrong ink to split when applying it to the garment. It is always better to use butt registration.
Allow for Paper Shrinkage
Since the transfers cannot be printed wet-on-wet, the paper is getting heated in between every color. Making the paper shrink. Always run the paper through a dryer at 180-220 degrees to insure that you will get minimum shrinkage.
You can use many types of inks when transfer printing, but you will get the best results when using an ink that is formulated for transfers. The most common ink that w carry is Union Ultrasoft Series. It can be used as a hot-split or cold peel. But keep in mind, it will not be as opaque when using it as a hot split on a dark garment. I recommend the Maxopake series from Union, and adding transfer powder the the image, before senfing it down the dryer.
Typically you will press your transfers for 10-18 seconds, 35-50lbs of pressure, at 350-400 degrees. Hot splits can run at higher temperature, shorter time, and less pressure. Cold peels should be ran at a lower temperature, longer time, and higher pressure.