Inks can be mixed to closely simulate swatches from the Pantone Matching System. We keep a copy of both the Solid Coated and Solid Uncoated guides in our studio.
Once printed, the main type of inks we use are similar swatches from the Solid Coated book. The inks are slightly glossy and reflect a bit of light, so it's not possible to simulate Solid Uncoated swatches with our current ink process.
Both the Solid Coated and Solid Uncoated books contain inks printed onto paper. Screen printed inks applied to textiles behave a little bit differently due to difference in the ink and the texture of the garment, so it's important to note that it's not possible to perfectly match a Pantone Swatch, only to closely simulate it with the different ink type. There are optical differences due to the variables between ink and garment.
Ask your Account Executive for more details when exact colour accuracy is a concern!