I use Irish moss in my beers, but I still get chill haze. Could it be my mash time? Typically my beers spend 20 minutes in a protein rest at 120–125 °F (49–52 °C) and 40 minutes mashing at 150–160 °F (65–71 °C). then I lauter and boil. I have chill times around 30 minutes using a coil.
Jesse Kuiper
North Wales, Pennsylvania

Chill haze is the product of protein and polyphenol (tannin) interactions in beer and occur when beer is chilled, hence the name chill haze. There are various methods aimed at chill haze reduction and they all either are based on reducing the content of chill haze proteins and/or polyphenols. The first thing brewers can do to minimize haze is to begin with low protein raw materials. This is one of the reasons that the protein content and degree of modification of proteins in malt are of importance. Although some brewers frown upon the use of adjuncts, protein dilution of wort is beneficial to a certain degree when higher protein barley is used for malting.
   
Irish moss added in the kettle reacts with hot break to form larger trub flocs that settle more quickly than smaller flocs. Many brewers today use silica gels prior to filtration to remove even more protein. Polyvinylpolypyrrolidone (PVPP) can be added alone or in conjunction with silica gel, and PVPP is used to remove the polyphenol component of haze. In all cases, a cold aging step prior to packaging allows chill haze to form and permits its removal by gravity sedimentation or filtration. Ale brewers often add isinglass finings to remove yeast, but isinglass also removes some haze forming proteins.
   
In my opinion neither mash time nor mash profile are significant contributors to chill haze. It is certainly true that longer mashes remove more protein in the mash than shorter mashes, but long mashes and those mashes using low temperature protein rests are not commonly used to specifically address chill haze.
   
I have a Teutonic view of chill haze control and it seems to work for most of our beers. We begin with high-quality 2-row malt that tends to be on the lower end of total protein (10.5–11%). In the brewhouse we use the mash profile that works for what we want in terms of beer flavor and no special concern is given to haze control. During boiling we evaporate about 6–8% of the kettle full volume and no finings are added. We use no finings before filtration, but we do hold our beers awaiting filtration at 30–32 °F (-1–0 °C) for several days to allow chill haze to form. This works for all of our beers except beers that are dry-hopped as well as those that begin with under-modified Pilsner malt. If I had to correct the haze in these two beers I would use PVPP to go after tannins in dry-hopped beers and silica gel for the haze forming proteins associated with under-modified malt. But a little haze is not a bad thing in some beers and I prefer to let the flavor express itself without excessive meddling.