Seal the knots of the wood with shellac sealer. This is necessary in the new wood is very dry yet for this story reforms . If the wood is light, use white shellac, is transparent. Areas treated with shellac will not accept the patina just as well that the wood smooth, so try to apply it only on the knot. To do this, pour on a rag and rub some solution either on the nodes. It will dry quickly.
