I have a kegerator that holds two, five gallon kegs. The kegs are charged at 25 psi CO2 for two weeks at 70°F (21°C). When I place a keg in the kegerator I release the pressure on the keg. Once placed in the kegerator the kegs are set to 8 psi at 40°F (4°C).
When I pour the beer a head of both stiff and soft foam forms. The soft foam eventually dissipates into beer. The stiff foam holds it's shape. I generally remove the stiff foam with a spoon and then pour more beer into the glass to fill it.
I have tried various levels of CO2, as low as 6 psi in the keg (40°F) and 20 psi to charge (70°F). This has not changed the fact that there is stiff foam. This happens consistently across multiple styles of beer.
The lines from the keg to the tap are 1/4 inch wide (id), and 10 feet long. They are stored coiled, horizontally, above the top the kegs.
How can I prevent the stiff foam from forming?