John,

On the exterior I recommend clean off either by scraping by hand or w/ a 
pressure washer. Remove loose/deteriorated mortar from joints. Repoint 
w/ a mix of 1 part gray Portland, 1 part hydrated lime (NOT agricultural 
lime), 6 parts mason's sand.

On interior.... remove Thoroseal that comes off easily. Don't worry 
about what does not. Trying to remove what does not come off easy will 
create more damage than good. I doubt that the Thoroseal is the problem.

Do not repaint the exterior.

Ken

> A friend sends this. Can you offer a suggestion?
>
> >>Before I knew up from down, I coated the interior of a painted red 
> brick foundation with thoroughseal. Stopping the wall from breathing 
> has caused major mortar failures on the exterior bricks. I know 
> Portland cement will destroy the bricks because it is so hard. What 
> mortar mix should I use? How should I remove the interior sealer to be 
> able to repaint the exterior side in spring? Help is needed to fix 
> this mess. Thanks, hugely.
> Skip <<

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