A Neutral barrel has been used several times and no longer imparts color or flavor. wine or liquor stored in neutral un-coated barrels which don’t impart color and flavor and is stored in the proper temperature and humidity, like a wine cellar, that evaporation can take place through the pores of the wood and the ingredients may come out denser and have a more intense flavor but new mini barrels impart so much color and flavor so quickly that the ingredients cannot be left inside long enough for evaporation to take place, there would be too much flavor from the oak, at least not until the barrel has been used several times, and there isn't much color and flavor left.
MILAGRO SELECT BARREL RESERVE SILVER, according to their web site “ is mellowed in both American and French oak barrels for 30 days”; I have not toured their distillery and don’t know any of their workers but if this is true, they use 200 liter barrels not 5 liter barrels, (5 Liter barrels provide each liter of spirits with a great deal more oak character than a larger barrel due to the ratio of surface area to tequila volume. Because of this the same degree of flavor change is observed in a far shorter period of time, perhaps only a few weeks. Spirits in a small barrel requires constant monitoring to ensure it does not become over oaked) and the barrels would have to be completely neutral, even then I don’t see it coming out so clear, no color at all. Seems to me they would have to use some kind of filtering process to make it come out so clear but like I said, I haven’t toured their distillery, I have not heard of their distillery, don’t know where it is, but have a suspicion that they are buying from another distillery and putting it in their bottles and I think I know from who. I’ll ask around some of tequila distillery tour guides and distillery workers.
I do know one of the other well-known distillers is taking 3 or 4 year barrel aged tequila and then filtering it back to clear tequila, I’ve tasted it only once but was very impressed, next time I see a bottle of it in the store I try it out. At your service Clay Johnston