Due to the translucent quality of ink, when printed over a transparent stock, the colors will be see-through and will look a lot lighter than they do when viewed on screen.
The surface which your transparent sticker will be placed on will greatly affect the overall appearance of the printed image. For example, when a transparent sticker is adhered to a white surface, the colors will appear more vibrant, opaque and closer to how they look in your proof. If the sticker is placed over a dark colored or patterned surface , it will reduce the visibility of your printed design. Additionally, when a transparent sticker is placed on a clear glass or a window, the colors can appear very light and will be the most see-through.
Overall, we recommend using dark colors when designing for transparent stickers and to avoid light colors as these will appear more translucent when printed and reduce the visibility of your printed artwork.
Alternatively, consider adding a white ink underlay to enhance the colors and visibility of your design. White ink is only available on our Super Matte Transparent or Super Gloss Transparent stocks.
See: How do I prepare files with white or metallic silver ink?