I just finished brewing a series of 5 Belgian beers, and at least 3 of them have exhibited problems with head formation and retention. I haven't tried the last 2 beers yet, so I can't say if those have the same problems.
In the Blonde, Dubbel and Tripel, I'll get a rush of carbonation after pouring and then a thin head that dissipates quickly. And I'm getting little to no lacing.
All of these beers used Belgian Pils as the base grain (following the recipes from 'Brewing Classic Styles') and were brewed using a partial mash approach, where about 50% of the beer's OG came from grain, the rest from pilsner DME and other fermentables.
The first two beers were bottle conditioned, while the tripel was force carbonated.
Other beers I've made have not had a head problem, so I don't think it's a water problem or something in my brewing system.
Any ideas on what could be causing this problem?