Huh... a little sediment may be visible after a while-- there _are_ some small particles in there from the coloring herbs-- but I've never seen a scum on top... Are you sure the bottle wasn't contaminated somehow (like, by direct-to-mouth contact)? Still, alcohol at that concentration is basically a disinfectant-- no critter should be able to live in there... If you send me the rest of the bottle, I promise to send you a full report on what I find...:)

@Salsa

I don't remember any direct-to-mouth contact... not saying that there wasn't any... just saying I don't remember any. ;-)

The only guess I might have is that the oils that produce the louche went rancid. ???

One question I might have is how you store your bottles. I keep mine on a shelf in a cool dark place and upright. Some of my absinthes are approx 10 years old now. I have seen some slight color changes, from a green to a yellowish green, or brown tinge, but from what Ive read, this is normal.

In the third photo, does it appear that this brown 'scum' is oily or of a dusty, moldy particular matter?

The absinthe was stored upright in a kitchen cabinet.

I don't think the scum was dusty or moldy, it didn't appear until after I added the water.

Did you shake the bottle vigorously before pouring a glass?
I would have done it after 1 1/2 year sitting opened.

>>>> Did you shake the bottle vigorously before pouring a glass?

I didn't shake it. While it was somewhat cloudy before I added the water, there didn't seem to be any solids in it before I added the water.

Do you think shaking it up would have helped?

Mebbe its from when U burnt the sugar.

An almost similar thing happened - and this may sound odd - to a louched verte sample I stored in the fridge for a couple of days, just curiosity, to find out what would happen. A comparable residue-like substance appeared, with only one slight exception to this phenomenon, a substantial amount of sediment was lying at the bottom of the sample bottle, though after a giving it a good shake al of it disappeared but returned again after another three days in the fridge, I’m sure there must be some simple, kind of a scientific explanation for it.

Some organic compounds tend to come out of solution and precipitate. Decreasing temperature decreases solubility (and possibly induces formation of crystals, e.g. anethole).

I have had a bottle of absinthe in the fridge for about a year -- is this a good idea or should it have been stored at room temperature? Just wondering!

i just bought a bottle of absinthe lucid, and i did the same thing put the original cork/cap back in it and i was wondering if i should keep it in like a cupboard or something cause im sure heat isnt best for it but i dunno i just dont want this 72 bottle of greatness to go bad what should i do for storage and is it even possible for absinthe to go bad?

I bought a bottle of Lucid that had been near a big window where sun was beaming in. The color wasn't right and the louche and effect was off so I spoke with the liquor store manager and she wouldn't return it and make good on it so I then emailed veridian(the good folks that bring you Lucid). They were very gracious and sent me a replacement bottle at no charge.