I have a few questions. What char level gives the most vanilla and caramel flavor? Is it safe to assume that american oak would be the best to get vanilla and caramel flavors? How do you remove the harsh tannins from oak spirals/staves/cubes/chips? Does boiling oak cubes and dumping the water before adding the cubes to the beer really remove the astringent / tannin? I've made several "barrel aged" beers and always had an issue with the tannin flavors. Very harsh and astringent. Sometimes (after 2 or 3 years), the wood flavor and tannins would die down, but mostly it would stay. I would typically soak the unboiled cubes or chips in a pint of bourbon for no more than 2 weeks and dump the bourbon and cubes into the secondary with the beer. Recently, I read an article that talked about boiling the oak cubes and then discarding the boiled water (which is theoretically filled with the tannins). Then you add the boiled oak cubes to a container and fill it with bourbon and age it a week or two (based on flavor). Then dump it into the secondary to age with the beer. What are your thoughts on this process?