Tallow based soaps are the gold standard for lathering, and Cella is awesome. I use it occasionally. This is what your lather should look like.
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As Larry mentioned, try stropping on the balsa wood, then back to your leather. How many passes on the leather strop are you doing after a shave? As you shave your beard will dull the razor, improper stropping technique or an inadequate number of passes will not bring back the level of sharpness you want. If that doesn't do it, then send it to Larry. A few strokes on a barber's hone will bring it back if you rolled it on the strop.