I did not seal the horn. Per web post by Two Feathers--inside scraped and loosely smoothed, one day bleach, .38 cal. rifle bore, 210 shotgun bore, bottle brush, one day denture tablets, 3 days bleach and a lot of scrubbing to make sure it was no longer slick, but was very clean inside. Outside of horn was scraped, sanded, steel-wooled, compounded, and waxed.