How to Hide Masonry Patches: Solving this Common Restoration Issue in the Field [Part 2]
In a recent post, I shared a story of a stone-patching restoration that was underway at the magnificent Ansonia, located along Broadway in New York City’s Upper West Side. On that project, we opted for a stain to get a color match between the patches and the substrate. We mixed our Potassium Silicate Coating and Liquid Silicate on-site to create the stain.
Note that our Potassium Silicate Coatings are opaque coatings/paints. A stain is made by adding clear Liquid Silicate to the Potassium Silicate Coating. More or less Liquid Silicate will determine how transparent the stain will be.
Two other options for color matching patches are: an opaque Potassium Silicate coating and a custom color mortar (which you can get with a laboratory color match or by tweaking mortar colors on-site).
The Coating Solution
If you know ahead of time that you’ll be using a coating, you’ll be less dependent on selecting a mortar that results in a perfect match. This approach saves time and money (especially if you avoid a custom color match) because the coating approach is intended to completely cover the surface, i.e., the mortar color will not be seen. And there are long-term cost benefits of using coatings, such as: added UV stability and added water resistance.
Before
After with a coating applied
The Mortar Solution
Custom color matching is is always an option (albeit an expensive option), but sometimes this custom match is not perfect for every part of the structure. That’s why I most often suggest that tweaking colors on-site is the best approach.
Tweaking mortar colors on-site (i.e., creating your own custom colors) is the ideal method when you will not be using a coating to finish your project. But you’ll want to avoid having too many colors to choose from. Instead, select two or three colors that get you close and use these as-is or combine the colors to tweak in one direction or another.
For example, you can start with three colors and end up with many more options. Label the different mix ratios as Color A, Color B, and so on. You’ll likely need to get these colors approved, so limit the number as much as you can.
Now when you walk the building with the approved samples, you can identify which color variant works best for each area.
Here are some great videos with master mason, Dennis Rude (CSP’s founder), demonstrating how to make your own custom colors on-site and techniques specific to limestone and brownstone.
In Conclusion
Color matching mortar patches is part skill and part planning. Whether your plan is to stain, coat, or tweak the actual mortar color, knowing ahead of time is critical. Contact me (tech@cathedralstone.com) if you need help in deciding which path is right for your project and budget.
Check out our complete YouTube channel here.
Here’s a link to our Potassium Silicate Coatings and Liquid Silicate.
