Excess of foam in dispensed NitroBrew’d beer is generally indicative of excess residual carbonation. And it is not necessarily the nitro-style creamy foam you would want.
Insufficient mixing/shaking is a common problem because it is so counter-intuitive. Whenever folks see excessive foam, they tend to mix less vigorously because usually wild pours are associated with disturbed beer 🙂
Certain factors may interfere with NitroBrew’s carbonation adjustment function, for example: – if the beer is too cold (i.e., less than 38degF) – stock beer is over carbonated (more than 2.65 volumes) – improper equilibration, i.e., insufficient mixing/shaking after charging – use of beer gas (N2/CO2 mixes) to NitroBrew normally carbonated stock beer, etc.
Lastly, if you have a pocket of untreated beer in the NitroBrew kettle (due to incomplete mixing), that slug of higher carbonation beer will ‘explode’ when it hits the millions of nitro style microbubbles during dispense. Nitro bubbles nucleate CO2 release much like those coca-cola and mentos experiments 🙂
Good mixing is important- both for carbonation adjustment and nitrogen infusion. Also, we recommend holding the kettle by the body (not the handle) while shaking.