astringency from over crushed malt

[Cestrian]

Just wondering if anyone has ever had a problem with astringency from over crushed malt. I didn’t even know this was a thing until quite recently, since doing a bit of research after problems with astringency. I am quite lucky in that my alkalinity is 20mg/L and calcium is only 20ppm, so as I mainly make pale ales, I have never worried about water chemistry, just thrown 3 or 4g of calcium chloride or gypsum in the mash and that’s that.
But the last 4 or 5 brews have been a nightmare. High pH on the sparge and low efficiency and a bad astringency in the finished beer to the point that it is undrinkable. So I went back to basics, checking everything water chemistry, pH, calibration of temperature probes. I tried adjusting sparge pH and reducing temperature. I have been brewing AG for 10 years and never had this problem before. Then all of a sudden it stopped. The last brew was fine.
I checked back through my brewing notes and all of the bad batches seemed to come from one sack of golden promise. Previously no problems then 5 dodgy brews with this sack and as soon as I started a new sack the problem has gone away. I can only think that the problem was caused by over crushed malt or I’ve been unlucky and had a sack of husks from the bottom of a silo off the maltster. I don’t know, anyone ever heard of this before?

 

[MyQul]

Never come across this problem before. I sometimes mill my own grain and the cheapo mill I have mills it pretty fine. I've never had that problem (from crushed grain at least)

 

[foxy]

Just wondering if anyone has ever had a problem with astringency from over crushed malt. I didn’t even know this was a thing until quite recently, since doing a bit of research after problems with astringency. I am quite lucky in that my alkalinity is 20mg/L and calcium is only 20ppm, so as I mainly make pale ales, I have never worried about water chemistry, just thrown 3 or 4g of calcium chloride or gypsum in the mash and that’s that.
But the last 4 or 5 brews have been a nightmare. High pH on the sparge and low efficiency and a bad astringency in the finished beer to the point that it is undrinkable. So I went back to basics, checking everything water chemistry, pH, calibration of temperature probes. I tried adjusting sparge pH and reducing temperature. I have been brewing AG for 10 years and never had this problem before. Then all of a sudden it stopped. The last brew was fine.
I checked back through my brewing notes and all of the bad batches seemed to come from one sack of golden promise. Previously no problems then 5 dodgy brews with this sack and as soon as I started a new sack the problem has gone away. I can only think that the problem was caused by over crushed malt or I’ve been unlucky and had a sack of husks from the bottom of a silo off the maltster. I don’t know, anyone ever heard of this before?

Yes fine crush is known for causing astringency, your high pH on the sparge wouldn't help either.
Three good reasons for milling your own grain.
1. You can check the freshness of the grain you have purchased.
2. Control over the crush of the grain.
3. Intact grain when purchased will last far longer than ready crushed grain. Especially when buying in bulk.