This is a legitimate question and for educating the bigger masses and for those that are interested I will outline the distinction between the printing system and how they might apply to your project. There are for the most part four printing methods, they are screen printing, heat transfer press, and weaving well this is not actually printing but I place it there as you still need to put a picture on a t shirt. The last and the latest technology are direct to garment. This cycle can create some fantastic high resolution photographic printing but it is at a cost.
Screen printing is most probable the most famous method of printing promotional t shirts, the set up process is like offset traditional printing methods where you want to give your pictures in to detachable variety documents, for instance assuming you have a four variety record you really want to supply a CMYK record which the print production firm can separate each tone and isolate them from one another creating, four separate print pictures, one for the cyan tone, one for magenta and one each for the yellow and K being dark or dim scale. Now that the CMYK documents have been separated a separate screen is delivered for each variety in total four screens a C screen, M screen, and one each for the Y and K screens. So each tone has its own separate screen.
What this implies is that each tone is printed separately on the promotional T shirt. Since the screens have been set and have been tested we can start the printing the t shirts. In summing up screen printing we note that there is quite a bit of setup work to be finished, you really want to permit a hefty lead time for the turnaround of the promotional T shirts, this content likewise as the setup cycle is so intensive there is a substantial cost required about 70 to 150 per variety so in a four variety print it would be between 280 and 600 relying upon the print, and you presently cannot seem to print one great promotional T shirt. Fortunately the setup is the costliest part of the screen printing process and from this point forward every t shirt is at an insignificant cost. To summarize, screen printing is the best interaction for delivering a lot of promotional T shirts, a base request of a couple hundred and upwards.