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French oak (''Quercus sessilis''/''Quercus petraea'' and ''Quercus robur'') contributes comparatively more [https://en.wikipedia.org/wiki/Trans-3-Methyl-4-octanolide trans-3-Methyl-4-octanolide] while American oak contributes more [https://en.wikipedia.org/wiki/Cis-3-Methyl-4-octanolide cis-3-Methyl-4-octanolide] to beer .<ref name='Review of oak aging for wine'>[http://www.sciencedirect.com/science/article/pii/S092422440600015X Review of quality factors on wine ageing in oak barrels. Garde-Cerdan and Ancin-Azpilicueta (2006)]</ref>. These lactones both contribute a coconut character but the cis-lactone has a much lower flavor and aroma threshold ,<ref>[http://www.sciencedirect.com/science/article/pii/S0023643805000150 Effect of oak barrel type on the volatile composition of wine: Storage time optimization. Garde-Cerdan and Ancin-Azpilicueta (2006)]</ref>, therefore American oak barrels may give more of a lactone flavor and aroma impact. ''Q. sessilis'' is more common in wine aging and ''Q. robur'' is more common for cognac barrels .<ref name='Review of oak aging for wine'/>

(''Quercus petraea'', or commonly Sessile Oak .<ref>[https://en.wikipedia.org/wiki/Quercus_petraea ''Quercus petraea''. Wikipedia. Retrieved 06/16/2018.]</ref><ref>Brandon Jones. Private correspondence with Dan Pixley. 06/16/2018.</ref>)

Chestnut (''Castanea sativa'') can be a cheaper alternative to oak for barrels. Chestnut barrels are used by some lambic producers (though generally most lambic barrels are oak). Chestnut allows more gas permeability than oak, and therefore will allow more oxygen transfer than a comparable barrel made out of oak.<ref>[http://link.springer.com/article/10.1007/s00217-010-1292-9 Effect of aging in new oak, one-year-used oak, chestnut barrels and bottle on color, phenolics and gustative profile of three monovarietal red wines. Gambuti et al., 2010]</ref>

Oxygen ingress will vary greatly even between the same type of barrels .<ref name="amaral_barrels">[https://www.facebook.com/groups/MilkTheFunk/permalink/1988872771140927/?comment_id=1989673027727568&comment_tracking=%7B%22tn%22%3A%22R0%22%7D Justin Amaral. Milk the Funk Facebook post on measuring oxygen in barrels. 02/15/2018.]</ref>.

Sherry barrels typically have the most oxygen ingress .<ref name="amaral_barrels" />.

Spirit barrels typically have less oxygen ingress than sherry barrels, but more than wine barrels. This also depends on the condition and char level of the spirit barrel .<ref name="amaral_barrels" />.

Wine barrels typically have less oxygen ingress than spirit and sherry barrels .<ref name="amaral_barrels" />. A standard 60 gallon Bordeux Chateau barrel weighs around 100 pounds (50 kg) empty, and about 600 pounds (275 kg) full .<ref>[http://socialvignerons.com/2016/06/27/anatomy-of-a-wine-barrel-parts-sizes-infographic/ Julien Miguel. "Anatomy of a Wine Barrel: Parts, Sizes, Infographic". Social Vignerons website. 06/27/2016. Retrieved 07/31/2018.]</ref>.

French wine barrels will have their hoops secured into place by nails. If the staves need to be tightened during swelling, then the nails must be removed. The nails can be removed with pliers or a hoop driver so that the hoops can be tightened. After tightening, the nails can be hammered back in, although some brewers just leave the nails out permanently. Justin Amaral recommends buying nails from Barrel Builders as they are reportedly easier to remove . <ref>[https://www.facebook.com/groups/MilkTheFunk/permalink/1963764150318456/?comment_id=1963786806982857&comment_tracking=%7B%22tn%22%3A%22R%22%7D Joseph Kearns, Justin Amaral, and Andrew Zinn. MTF thread about tightening hoops on French oak barrels. 01/23/2018.]</ref>.