I have head retention problems in an extract bock, and I've been working my way through the potential issues. It's in a keezer.

• Line length is 8ft
• Pressure is 14psi (I live at 5,000ft)
• Pour time is 8-9 seconds
• Fan circulates air
• Keezer is 38F
• Lines are coiled on top of keg, no CO2 breakout in the lines
• I'm confident in the carbonation levels, it has been slow-carbing for months

Once the beer hits the glass, the CO2 rapidly breaks out, forming glassy bubbles instead of white foam, and it sounds like a soda. A strong head of these glassy bubbles appears, but quickly dissipates leaving the beer completely flat.

• I've experimented with chilling the glasses, which helps but does not solve the problem.

• I've worked on "beer clean glassware", scrubbing with a brush & baking soda/salt. They might not be "beer clean", but commercial beer has good head & lacing in the same glasses vs my bock.

At this point I'm thinking I must have some detergent traces in the beer- I used to clean my kettle and a few other elements for the boil with soap. I stopped a while ago, but there could still be residue.

Any ideas of other possible causes?

If it is detergent in the beer, is there anything I can do to save it?