A fine day for taking mortar and salt analysis samples for testing to help inform our clients as to the most sensitive way of conserving the Kings Gate at Caernarfon Castle, as part of the most recent proposals for enhancing the castle and roofing back over areas that have previously been exposed to the elements for a long time. We will test for the type of mortar using dissolution, heat loss and petrographic analysis and determine the types of the salts and residues found on the stone and in the mortar and make suggestions how the salt crystallisation can be controlled once the climate around some of these walls changes in the future.