The soldermasked panel is now ready for photoprinting the image.
Laying the following on top of each other.
Soldermask Phototool Side 1
Soldermasked Panel
Soldermask Phototool Side 2
Then a vacuum is created, which then creates close contact, this is then exposed  to Ultraviolet light (500mj @ 365nm), this then polymerises the soldermask under the clear parts of the phototool, making that part of the image insoluble in the subsequent developing solution.