small format oak , ie toasted chips and powders are used durring primary fermentation for a couple reasons.
due to large relative surface area , they are quick release so give up all their compounds in the fast time of a primary ferment,
they add some tannin , this rounds out the mouthfeel of the wine as the short chain seed tannins can bind into longer chains early reducing harshness.
they help fix colour compounds which can be full in the primary then fade as the wine ages . chips in the primary may be though of as a color stabilizer , helpfull with varieties like zinfandel which struggle to get nice colour , especialy with over cropped Central Valley fruit.
American oak chips and powders in the primary are the most effective way to reduce vegital character in underipe varieties of cabernet suav , cab franc and syrah. They also work very well with hybrid and native fruit , vegital character is minimised and fruit flavours shine.
chips and powders are intended for fermentation stage for these reasons and are not really intended as an aging stage oak addition. there are many compounds in the oak powder that are metabolised and buffered by the yeast in an active ferment . this is why oak in the primary doesn't add much oak flavour , NEWS FLASH its not supposed to . its the secondary benefits above you are shooting for.
this buffering of the oak results in good integration.
for a light red like pinot noir , 1g/litre is standard , for other reds like syrah or cab sauv , 2g/litre , for a hybrid red 4g/litre.
to get a good sence of this ( its harder to tell in a red wine , side by side batches , one control one with oak will highlight things ) also one might compare a chardonnay barrel fermented in a new barrel vs one simply stored in a new barrel.
one chardonnay is complex and smooth , the other , chateau plywood even if the time lapsed in a new barrel is the same ie 2 weeks .
for oak post fermentation , you want to use a larger format, slower release , less end grain character product , thats where cubes , spirals , staves and barrels come in. you are adding flavour and tannin at this stage.
