Oily residue

I bottled an Altbier tonight and as I was taking a gravity sample I noticed what can only be described as a thin oily film along the surface of the beer. I took a pic but you really can't see it unfortunately. I checked the other brew I have in secondary and It has the same thing. The beer tasted great and there were no signs of infection so I'm not stressed about it, I'm just curious if any one here has experienced the same thing or has an explanation.

Recipe? Sanitation/cleaning routine?

Yuri_Rage said:

Recipe? Sanitation/cleaning routine?

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1 lb. light DME (60 min)
6 lbs. Amber LME (5 min)
1 lb. Cara-Munich II
1 oz. Perle (60 min)
1 oz. Spalt (20 min)
1 oz. Spalt (5 min)
Wyeast 1338

I use PLC to clean all of my equipment, carboys and bottles and Iodophor to sanitize. I always soak my carboys for 1/2 hr. in an Iodophor solution before using. This is my regular procedure and it has worked well for me. I am fairly confident that the oily film was not related to my cleaning or sanitizing routine considering I haven't seen it before. It was in both carboys that were in the exact same place. I had a good seal on my rubber stoppers and I always keep my airlocks full of vodka. This one's got me puzzled.

Does it look alot like the oil slick that forms on top of a pot of cold coffee after about 12 hours? Lots of my beer has done this, I've always chalked it up to Hop Oil, and never given it much else thought. I sure would be interested in hearing what it really is.

BigKahuna said:

Does it look alot like the oil slick that forms on top of a pot of cold coffee after about 12 hours?

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Exactly. Hop oil crossed my mind as well, but I've made hoppier brews that didn't have it, or I just didn't notice.

There's been many times I've seen what looks exactly like a rainpuddle oil slick that rainbows across the top of my wort, but never had a problem with it. I just ignore it unless it smells funny.

An oily film is probably hop oils or fusel alcohols. If the latter, you'd taste them.

I just brewed a Porter a few nights ago. I noticed that right after I got everything in the fermenter. So in my case it's too early to be an infection or alcohol. Gotta be hop oil.

I came to this thread for the same reason...A slight, rainbowy slick on the the surface that I noticed when grabbing a sample. Smells and tastes fine, though. Kinda freaked me out.

Last Sunday I was doing an AG batch of porter and the "oil slick" was very noticeable as I was sparging the grains. I was somewhat puzzled but it provided with more amusement (hey honey, I've got a batch of motor oil for fermenting!) than concern.

No idea what it is but it was before I had put hops into it. Like I said, it was from the sparge water. Then again it was my first AG batch and my second batch of beer total.

Come to think of it....I've noticed it a lot more on AG batches than on Extracts. I wonder if there is just a bit of "vegetable Oil" in the grain that we are extracting?

I'm currently drinking this beer and all is fine. I'm sticking to the hop oil theory until I hear something different (they were both extract recipes). The pale ale I'm drinking had it too and it turned out phenomenal.

I've also heard that the surfactant in Star San can give you the same oil slick appearance from the residual amount of Star San that's left in the fermenter when you rack into it.

to many rainbows in here