Hi Sam,
I personally have not heard of anyone using high-pressure water to cut out mortar from brickwork. However, I would expect 20,000 psi could do it since mortar is usually pretty soft. Maybe a fixture to guide a hand lance along the mortar lines might work if the block is not too thick. How thick are the bricks and/or mortar?
We would also be happy to further discuss this application by phone. You can find a list of our regional branches at this link:
http://www.nlbcorp.com/branches.aspBest Regards,
Jenna Alder
NLB Marketing Asst.
alderjr@nlbusa.com(800) 441-5059