What you will need
An old set of cork backed placemats
Glue (I used self adhesive photo paper and did not need the glue)
Spray or brush on varnish or lacquer (I used the spray on variety as that was what I already had)
Step 1: Sand the old varnish and wet
You could use the sandpaper to remove the old image but I did not bother to go that far, I just removed the existing varnish.
Once the varnish is removed then I quickly placed the placemat under running water and then set it aside while I sanded the next placemat. I DID NOT soak the placemat or place a wet cloth over the top of the placemat as I only wanted to cause the image to lift off and did not want to risk causing the placemat itself to warp from getting too wet.