Preparation

Before I can apply a coat of paint to the basement wall there's a bit of prep work required.  All the joints between the blocks that are white have already been skim-coated with plaster.  The 100 year old original mortar has broken down at it's exposed surface and the plaster will work as a shield between the mortar and the open air.  The joints that still look dark are more deteriorated so I will be filling them with replacement (modern) mortar.