2-piper,
Yes that was a tried and tested method of sealing the pores, also they have used sil-glass.
Before using these mixtures they would 'bone ' the wood.
This involved vigorously rubbing the wood all over with a well dried cows rib bone to cause the pores to close by compression.The burnishing effect to the wood had a remarkable effect upon assisting to promote a splendid hard smooth finish.