Ok so a few questions about them.
1.) Sanitising them first, how do you do it ? For my brett porter I soaked my oak chips in rum for a week, then added them in. How would I sanitise the dominoes?? I guess I could soak in vodka, which would stop any flavour addition. The chips contributed some slight rum flavours to the porter, which was great, but for say, an oud bruin I'd like to keep the flavour all about the oak.
2.) How much per litre?. I think I used 15g total in my brett porter. I ended up straining them out, rinsing off and adding straight into an oud bruin ( I plan on adding a domino to one half of this beer ).
3.) How long? I guess longer = stronger.