METAL is our adhesion promoter for specialty substrates such as metals, glass, aluminum, HDPE, PVC, Polystyrene, and Coroplast. When applied properly, METAL helps ensure strong UV ink adhesion to these tough surfaces. For glass applications, only promote and print on the “float” or “tin” side of the glass. (Float/tin side of the glass will glow when illuminated with a black light.) Disclaimer: The promoter should be tested on the specific printing substrate using the specific printer chemistry prior to printing your project. For best results, apply the promoter to a small sample of the substrate prior to printing to ensure the promoter will not damage the substrate surface. Print a small test print on the promoted surface to ensure the specific ink chemistry used in your printer is compatible with the adhesion promoter. Allow minimum 24 hours after printing before testing adhesion.