Sublimation requires a tight marriage between the sublimation transfer paper and the blank product during pressing. If the paper shifts or is not firmly planted against the substrate, then the result will be ghosting or gassing out.
Ghosting is when you end up with a blurry image, typically characterized by a shadow effect along or outside of the edges. Gassing Out is when you end up with a “burst” of ink outside of the image area.
The key here is a tight fit between the transfer paper and the substrate. It’s a good practice to use heat resistant tape to secure the transfer to the product. Use care not to tape across the image area as this can often damage the image quality. In addition, use only a minimal amount of tape, as you will need to be able to easily and quickly remove the transfer after pressing.
When sublimating apparel, you can use “repositionable” spray adhesive instead of tape. Apply a very light mist on the image side of the transfer paper from about 12-18" away. Do not spray the shirt. Then press the transfer paper to the product. If you position it incorrectly, you can lift it off and reposition it.
Regardless of how you adhere the transfer paper to the product, it’s important that when you remove it, it doesn’t slide along the surface of the substrate, as this may spread sublimation dye into unwanted areas, and cause ghosting. Ideally, with hard substrates, the transfer will be lifted off the surface, quickly and cleanly. With apparel, it may work better to grab one end of the paper and pull it away slowly, while firmly holding the garment down.
If your teflon blowout sheet becomes stained or dirty, it can also cause ghosting. You may want to consider using newsprint or butcher paper instead of teflon. Be sure to use a fresh sheet on every pressing cycle.