Slightly astringent aftertaste

I finally got my ale pipeline flowing again after a 2 month hiatus. My last two batches of ale have a slightly astringent aftertaste. Not enough to ruin my beer, just enough to piss me off and give a complex. They were both brewed in the summer or late summer, but I don't think the temps got that hot. Both were fermented with WL California ale yeast (recycled) with a starter. I always shake the hell out my grain bag to get the dusties out before steeping. I think it could be either a mild infection from adding 2 gal of cold tap water to my chilled wort, the recycled yeast could have picked up something along the way, or who knows what. I just brewed my pumpkin ale with fresh WL0001, we'll see how that one turns out. Maybe I'm just spoiled from drinking bottled craft brew.

Did you do anything to remove the chlorine or chloramine from the tap water? I was getting a nasty taste that was described as astringency, before someone mentioned that I should be treating my water for chloramine. I have been brewing with distilled water since then, and bought some campden tablets for getting the chloramine out of other water that I use.

If that isn't it, you can get astringency from steeping grains. I have been attempting to follow the so-called Colby method of steeping, copied and pasted to many threads, from a PM written by user Saccharomyces:

"- Start with 1 gallon of Campden treated RO water and 1 tsp of 5.2 pH stabilizer in the kettle. Stir in 1 lb of dry extract while heating to 165*F. At 165*F remove from heat. Drop in the steeping grain bag, tea bag it to get the grains wet and let it sit 30 minutes. Steeping in a small volume with pH stabilizer and extract keeps the pH around 5.2 which will prevent extracting tannins from the grain husks, which is the most common off flavor in extract beers.
- Drop a strainer over the pot and move the grain bag to the strainer. Run your top-off water slowly over the grains to rinse them until you get to your desired boil volume. Stir in 1/3 of the remaining extract for a partial boil, or 2/3 if doing a full volume boil, and bring to a boil. Add your bittering hops.
- With 15 minutes left in the boil, add a whirlfloc tablet, yeast nutrient, and the rest of your extract (do this off the heat so you don't scorch of course!).
- Stir continuously while chilling until the wort drops below 140*F. Chris uses an immersion chiller in his sink and then moves to an ice bath until he gets down to pitching temp. I already gave you my method, while more hands-on it works too."

Here is some info from Howtobrew.com:

Astringent
Astringency differs from bitterness by having a puckering quality, like sucking on a tea bag. It is dry, kind of powdery and is often the result of steeping grains too long or when the pH of the mash exceeds the range of 5.2 - 5.6. Oversparging the mash or using water that is too hot are common causes for exceeding the mash pH range. It can also be caused by over-hopping during either the bittering or finishing stages. Bacterial infections can also cause astringency, i.e. vinegar tones from aceto bacteria.

The brown scum that forms during fermentation and clings to the side of the fermentor is intensely bitter and if it is stirred back into the beer it will cause very astringent tastes. The scum should be removed from the beer, either by letting it cling undisturbed to the sides of an oversize fermentor, or by skimming it off the krausen, or blowing off the krausen itself from a 5 gallon carboy. I have never had any problems by simply letting it cling to the sides of the fermentor.

+1 on the chloramines....a very miniscule amount is perceivable on the pallet.

I really don't know how to describe the yucky taste my beers had before I started using a carbon based filter but I really disliked it so much I almost put all my stuff on Craig's List. Now I really enjoy my own beer and love sharing it with my friends and neighbors. Amazing difference in taste just by ditching the chlorine.

It's now about 10 days later and the same batch of brew appears to have lost the astringency. I had a six-pack in the fridge and over the course of 4-5 days the aftertaste is no longer perceivable. I just threw a room-termperature six-pack in the fridge last night, we'll see how this one tastes. This has been a very "slow" batch to ripen from the get go. In spite of the fact that I used a 1L starter, fermentation was very slow and less than vigorous. It also took the two full weeks to carbonate, and another 3 weeks to lose the astringency, which I didn't expect to lose. I bottle my pumpkin ale this weekend, we'll se how that one tastes.