Ribbon Pointing
To follow up on the crack in the stone foundation of the house with the improper slope. I want to discuss the ribbon joint that had to be pointed to match the existing ribbon joint. We always first remove the old joint and clean out the dust and debris from the stone joint. I even like to vacuum out the debris and dust to ensure a great bond. Good mortar bonds occur when there is a clean base and enough moisture in the new mortar to pull the moisture from the new into the old. This is where the bond first occurs. If a contractor is not cleaning out the joints properly, then a proper bond will not happen. It may look like it has and you’ll pay them for the job but sooner then later it will begin to unbond and fall out. I see it all the time!!
With the ribbon joint ,you have to first pack out the stone joint with your mix. When your going to cut a stone joint then a bar sand must be used. Don’t let anyone use any other sand to do ribbon joints. Using bar sand will allow the person to cut the joint properly as required, without the small pebbles that come in concrete sand.
Look at the existing stone joints and see if the stone joint comes out past the stone face or is recessed in towards the stone face. Either case, in stone pointing restoration your job is to match the original at all cost. After packing out the joint I’ll grab my one inch margin trowel and put a tight steel trowel finish on the joint. this gives the stone joint a nice smooth finish.
Each joint will vary in the size of the ribbon joint. Most ribbon joints are in the one inch wide range but will vary alot. Grab two razor blades and find a object that is one inch wide that you can hold in your hand. Tape the two blades on either side of the object so that razor part is flush with the object and even with one another.
If the stone joint is a level one then you’ll need a small two foot level to keep things straight. Some ribbon joints follow the contour of the stone. Either way, do what is original. Grab your mortar cutter and level and lightly run the razors across the top of your level. Lightly make the two lines into the stone joints. Don’t go to deep into the joint or you’ll have a problem cutting. All your doing is making lines to follow. Use your margin trowel now to cut back away from the lines. The top line in the mortar joint will need you to scrape upwards, the bottom line you’ll scrape downward. Once you have both lines scraped you’ll reveal the nice straight Ribbon joint you just created.
This stone joint is by far the hardest one to learn but once you got it down you can do all of them. After the joint has dried ,please give the ribbon joint a light brush. Good luck from john the mason and help with masonry.com