I brewed a hard root beer 2-3 months ago. Right from the start the beers have been way too foamy. I've had to pour each one into a pitcher in order to contain the foam. The basics of the recipe was a light ale with root beer concentrate and brown sugar added. The recipe called to mix the brown sugar cold. I didn't think that was right but did it anyhow. There is residue in each bottle that I think might be brown sugar that never dissolved. If it is brown sugar, could that be the cause of the foam. I want to do another batch, but want to correct the foamy issue.
No dissolved CO2 = no foam. Even the soapiest, lipid/protean saturated liquids don't foam if there are no included/dissolved gasses. So one thing to try is to reduce the amount of sugar added.
Dissolving the brown sugar in cold water is not unreasonable but dissolving it in (less volume of) boiled water and then diluting down will pasteurise the sugar to reduce the possible effect of other "wild" bacteria/fungi.
Unfortunately the question gives too little detail about process and ingredients to give a more accurate answer. How is this brew fermented? When is it bottled and what is the F.G of the bottled brew? What priming of the bottled brew (if any) is done?