[dee]

I've been getting some astringency in my darker beers lately.  It's not overwhelming and maybe it's in my head since I've been tweaking my brewing water.  I've had my water tested and I have soft water(Ca 12, Mg 2, Na 7, Cl 9, S04 5, CaCO3 26).  I make great 3-14SRM beers with very small additons but I'm not as pleased with my 25+SRM beers.  I've used several different water spreadsheets and shoot for the midrange of RA for the given color.  I add chalk and baking soda to my mash for these dark beers with a bias toward chalk but still taste some astringency.  My ph checks with strips indicate that I'm in the correct mash ph range so what else could I be doing?  Is it just me?  Is it the roasted and chocolate malts that I tasting in these dark beers?  Could the grain be too old?  None of my friends seem to taste it but I'm not sure they are sophisticated enough to know.  Should I aim for the high end with my mash additions.  My beers seem to come out a little darker than Beersmith calculates but I edit the SRM values to match what my grain bags say they are in each recipe.  I batch sparge and do a mashout with 190df water and usually end up 168-170df after adding all of my sparge water.  I'm considering going 5 degrees lower or just warm water sparging just to make sure I'm not getting tannins.  Thoughts?    

[a10t2]

Is it the roasted and chocolate malts that I tasting in these dark beers?

It sounds like you're doing everything else right, so that could be it.

One other thing I've noticed is that for extremely dark beers, the mash chemistry calculators tend to overestimate the RA needed. You may be able to cut back on the carbonates and still get your pH in range.

[MDixon]

Let's be clear, astringency is not something you taste, it is something you FEEL, a sensation.

[dee]

I understand what you're saying.  To me it is a drying sensation that I would associate with coffee.  I may try mashing higher or going with a little more crystal and see what I taste.  Maybe its just me trying to second guess my adjustments.  Nobody else seems to taste anything unusual.  Most of my beers have turned out exceptionally dry and well attenuated lately so maybe that's it.   

[yaleterrace]

maybe its just me, but i never go above 175 on the high-end for mash-out with a batch sparge.  the closer i get to 170, the less tannic and astringent my ales are.  then again, i did a one step decoction for my last pale, and that 212d didnt hurt anything.

[nyakavt]

Kai's recent post on polyphenol concentration based on crush method may be worth looking at.  I don't know if you could have a significant effect with it, but you could try crushing your roasted grains less fine, conditioning your malt, or use a dehusked version like carafa special.  There's also things you can do like a cold steep of roasted grains the night before (just use the water in the mash, and you may need more roasted malt), or you can add your roasted grains late in the mash to prevent extracting a lot of the harsher stuff from them.  I haven't tried any of this stuff, just things I've read about.

I had the same issue with my dark beers and went through all sorts of stuff trying to adjust the water.  I've come to realize that I don't like really roasted beer that much.  I'm also not a coffee drinker, probably the same set of tastes.  Is this a flavor you are getting, like harsh roast, burnt coffee?  If so, then that is not astringency.  Astringency is a mouthfeel that gives a puckering sensation like tea or dry red wine.  You could have a combination of astringency and acridness going on. 

An excessively low mash pH can cause an excessively harsh roast character, so make sure to check your mash pH with a reliable method no matter what spreadsheet you use.  If your mash pH checks out in the correct range then you aren't extracting excessive polyphenols from the grain, and water adjustments are not going to do much to fix the problem, at least in my experience. 

[dee]

Thanks for all of the suggestions guys.  I'm thinking maybe the combiantion of roasted malt, low mash temps and high attenuation may have me confusing dryness with astringency.  By no means is it at a mouth puckering level but reminded be more of coffee acidity.  I think I'm going to raise my mash temps and see if that is it.  As far as crushing, I had considered that but I've never moved my Barley Crusher off of the factory settting and get about 75% efficiency.  I've never had a stuck sparge so I don't think that's it.   

[denny]

maybe its just me, but i never go above 175 on the high-end for mash-out with a batch sparge.  the closer i get to 170, the less tannic and astringent my ales are.  then again, i did a one step decoction for my last pale, and that 212d didnt hurt anything.

pH is far more of a factor than temp.  As you pointed out, you can boil the grain for a decoction as long as the pH is in line.