Be sure that all loose or missing
mortar is re-tucked. Before any primer or paint can
be applied, mortar must cure for at least 30 days,
and we like 60 days. Test kits are available for checking
the alkalinity of mortar before painting. Get the
mortar joints repaired as soon as possible, so it
will have the most time possible to freely cure before
coating and caulking is applied.
Any contamination such as mildew, vegetation, dirt, etc. must be removed prior to coating. Power washing is sometimes an option, but must be used cautiously so as to not damage the brick or possibly water damage interior surfaces if large gaps and cracks exist around windows and between bricks. The advantage to power washing is speed and efficiency.
If we can't power wash, we substitute that power with manual labor, some stiff scrub brushes, long poles, and some specialized cleaning products. If you think you may need to wash the building by hand, you may want to break it into small projects one side at a time . The surface to be painted must be free of dust or powder, and may even require a dry stiff brush after the building dries. You'll want to wash the building and allow to dry for five days before painting , with an absolute minimum of three day's drying, so plan ahead. Just don't wash more than two weeks before you plan to prime.
For our projects, we recommend priming brick with an Elastomeric Primer. This is a water-based penetrating primer designed to tolerate the high alkalinity usually present in bricks and mortar. If the mortar or brick is extremely soft and powdery, you may have to consider one of OKON's siloxane/acrylic based sealers to help solidify the surface. We test an area by first trying the elastomeric primer and evaluating the result.
After the brick is primed or sealed, it will require caulking to seal any areas of possible moisture intrusion. Any visible cracks must be sealed with elastomeric or urethane caulk. Never apply caulking to an unprimed or unsealed joint. Your two finish coats will usually be a premium 100% ACRYLIC House paint. In addition, Siloxane/Acrylic blended additives are available to tremendously improve the water repellency of many traditional paint products.