There are two different ways that all-over printed shirts can be made. It can be done using what is called cut-and-sew, and then the easier pre-made shirt, which is sublimated as is. Both have their advantages, but like everything else, have disadvantages as well!
The cut-and-sew style has become more and more popular over the last few years. This application is done by designing the garment in pieces, meaning you will have your front, back, sleeves, collar, etc. Once they are designed, you then print your transfer. From this point, pressing is either done with cut pieces that are already cut to the correct shape, or with just a big piece of fabric that is sublimated and cut after the fact.
Sewing the pieces together this way eliminates any kind of crease marks you will see on shirts. These marks usually reside around the collar, or up the side and underneath of the sleeve. This method is more labor intensive because you need to have someone that can sew the pieces together in a timely manner, as they will be sewing a complete order from scratch and will be on whatever timeframe you gave your customer.
The other way to execute an all-over print is with a pre-made shirt. This way is definitely easier than the cut-and-sew style in our opinion, but you will have some imperfections that you and your customer will have to be ok with. To produce a shirt this way, you follow the same plan as the cut-and-sew option with just a few changes.
Your template will essentially be a T-shirt outline. You design within this template. You will have a couple different templates depending on the size of shirt. (These may be available through your supplier. It never hurts to ask!) You want to have a template so you can save a little money on ink as you won’t be laying down as much as if you were simply to have a big rectangle with the design and lay your shirt inside it.
To prepare your shirt for pressing, you will want to pre-press the garment. Lay it out as flat you can and then pre-press. This will get the shirt as flat and wrinkle free as possible. Pre-pressing can decrease the amount of the fold creases that you see on your shirt when you sublimate it. When you sublimate a pre-made shirt, you will never completely get rid of the creases, but you can minimize them depending on your press process and type of shirt you are using.
-Kevin Lumberg, Johnson Plastics Plus