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Stuck Mash - Preventing and Dealing With a Stuck Mash

A Stuck Mash Should Never Ruin a Beer


Dealing With a Stuck Mash

Sometimes mashes get stuck anyway. It’s not over, though. Remember, a stuck mash should never spoil a beer.

Is It Really Stuck? The first thing to do is make sure that it’s really stuck. It is better to wait another hour or so for a slow mash than to start mucking around with the situation. Actually, you can wait quite a while without seriously affecting the quality of the beer. Once I was making a brown ale and things were simply not going well. I got started late, had trouble crushing the grains, and had to rush out to replace my propane tank when I was trying heat my strike water. By the time I was ready to start sparging the sun was beginning to set. I would have finished up but my mash started draining excruciatingly slow. It was down to drips. By this time I was too tired and frustrated to try to deal with it so I emptied all over my sparge water into the lauter tun, covered everything as much as I could, left the drain open and called it a day. The next morning, my boil vessel was full. I went ahead with the boil and the beer turned out just fine.

So, if you’ve got the time and patience you can let a slow mash go at it’s own pace. I would never recommend emptying all of the sparge water as I did. Sparge at a slow enough rate to match the drain.

But, if you truly have a stuck mash or you simply don’t have the patience to wait it out here are a few ways that you can get it unstuck.


The first thing that you can try once you’re committed to the problem is to stir the mash. This advice is in direct opposition to what I said earlier but once the mash is stuck there’s no need to try to maintain the grain bed. If you’re trying to correct a slow mash then this step might stop it completely.

When you stir, try to scrap the top of the wort collection manifold to loosen any grains that may be clogging the holes. If this works it could be a temporary solution as whatever it causing the problem will likely repeat itself. You might have to occasionally stir and scrap until the mash drains completely. This could cause some of the grains clogging the holes to be pushed through and wind up in your boil vessel. A few grains won’t hurt but if it continues grab a colander with fairly fine holes and run the wort through it. Too many grains in the boil can affect the character of your beer.


If stirring doesn’t help the problem more drastic measures may be in order. Gravity drives the drainage system so any clog is held in place by the constant pressure of the wort and grains trying to get past it. A quick shove on the other side of the drain can fix the problem.

Open the drainage valve all the way and blow into the tube with a quick sharp burst. Remember that drainage tube could be quite hot so use caution. If this works, the hot wort will start flowing again quite rapidly so be ready to aim the tube away from your face and into the boil vessel. Once it’s flowing nicely, turn the valve back down to a trickle.
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