The typical postcards are printed on a 300gsm paper with a high gloss front and an uncoated back.
To achieve a briliant UV high gloss varnish front please select under "Finishing –> UV gloss varnish 1-sided”.
Due to the UV gloss varnish the colours seem to be more vibrant and also reflecting the light better.
Furthermore, the gloss varnish protects the surface of the printed card and gives it more stability.