Although I am a devout traditionalist and prefer to keep the use of portland cements to a minimum, the patching process of mortar repair, when dealing with natural stone buildings, should allow for a strong and durable patch. All patching and pointing shall be installed utilising soaking methods; working with optimal moisture content in both substrate and mortar. This basically means that substrates remain dampened before and after pointing/ patching has occurred.
While the colour may look darker now, the patch will dry lighter to match the colour of the surrounding stone. The skill of the original mason from many years ago has been highlighted again by this restoration.