Custom T-shirt Screen Printing involves a number of steps, all of which are essential to a high quality printed t-shirt. The first step is obviously preparing the artwork, then followed by screen coating, stencil/film printing, exposure of the emulsion on the coated screen, washing out and finally printing. Washing up the screens and emulsion removal for screen reuse are the final steps in the screen printing t-shirt cycle. If any of these processes fail the final product will be sub-optimal. A short video from fourambition illustrates all the steps.
1. Vector artwork. If possible supply the artwork in vector form (eps, ai, pdf, or cdr). The benefits are that file sizes are minimised and our rip (raster image processor) outputs a sharper film/stencil compared the same design submitted in raster form (jpg, png, gif). The reason being that if you rasterise the artwork in photoshop, our rip will rasterise the artwork again while printing. 2 levels of degradation. If you supply vector artwork, only 1 level of degradation occurs when the rip rasterises the artwork for t-shirt printing.
Besides producing a sharper stencil, vector artwork is much easier to separate than raster artwork for screen printing. If the design consists of multiple colours the screen printer has to make a separate screen for each colour. Vector artwork makes this step a breeze. If the artwork is a flattened png file, more time is required.
2. Use Black K=100 and not rich black if supplying separated artwork. We have calibrated our rip and film output printer to produce best results with K=100. There are many variations of rich black and some other screen printers may prefer a variation of rich black for film output but with us we need K=100 for best results. What black you need depends on the rip the screen printer is using. With K=100 our system lays down enough black ink to block ultraviolet light and just enough so that the black ink does not bleed into unwanted areas (also known as dot gain).
3. Outline text and have raster elements at 300 dpi. Remember to outline the text in case we do not have the font you have used installed and to keep the file sizes smaller. 300 dpi seems to be the sweet spot for film output for screen printing. Any higher and the resolution will not hold. Any lower and unwanted pixelisation may occur in the screen printed t-shirt.
4. Contrast. Have a lot of contrast in your design. It is very difficult to print fine gradients with the t-shirt screen printing process. You will not see a difference if your colours are C=100 and C=95 but you will if its C=100 v C=80. Screen printing is a mechanical process which is not very precise so we need a lot more leeway compared to offset or digital printing.
5. Other considerations. Provide a mock up if you have an unusual position for your artwork. A picture is worth a thousand words. Supply PMS colours if you need an exact colour match for corporate logos.
If you follow these guidelines, your screen printing t-shirt order will proceed more smoothly.