Repointing 1930's mortar.
Mortar from the 30's is most likely a high lime portland mortar. For tuckpointing, aside from the color match, you need to use a soft mortar, especially in a freeze/thaw climate.
Grind the joints to the same thickness of the joint, use a Type N mortar, and make certain to tool the joints.
For matching color, use powdered pigment and make proportional sample batches. Start light and add pigment. Smear the mortar onto a piece of plywood and dry it with a hairdryer, this way you can test samples in seconds.
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