Glass bottles syrup shrinkage and “floaties”

[KJamesJR]

This is a two part question...

I’ve been bottling in 12oz glass. When I reheat the syrup to bottle I fill it to the threads. Then once it cools the syrup shrinks down almost an entire inch leaving what I would consider, too much head room. I’m trying to bottle around 180 degrees but feel as if I’m going to hot and pouring expanded liquid. Is this normal?

Secondly I’m getting some really fine floaters in the syrup. They look like strands of fiber too thin to be your average hair. I am using a new synthetic filter and wash it before and after each use. I can only assume these fibers are coming from the filter. It’s not in every bottle but I have a few with these hairs in them from different batches. Can I empty these bottles, refilter and fill with new caps? I read somewheres you’re not supposed to reuse bottles but these are brand new bottles and I’d hate to waste them.

[ecolbeck]

I can only speak to the first question. Syrup does shrink significantly as it cools. This causes an increase in the density which is why there are two lines on a hydrometer (211 and 60 F). My understanding is that you should be bottling at 180 or above so I wouldn't lower the bottling temperature in an attempt to moderate the "shrinkage." Are you already filling the bottles as full as possible? Perhaps the bottles you are using have too long and thin a neck so the shrinkage is more noticeable.

[maple flats]

Filling the bottle with hot (180-190F) syrup to the bottom of the threads is proper fill, as the syrup cools and contracts, that helps form the seal, just like with canning jars and any bottle you buy with anything that was hot packed, the top is held down by a vacuum, then it pops up when you start to open the cap. Opening the cap on syrup will not pop because as you turn the cap the vacuum is lost slower and besides the cap did not pop down, just the seal.
Concerning the fibers in the finished syrup, How are you washing the filter, How do you expel excess water and how do you dry it? My thought is that the filter has been damaged. Try double filtering to see if the filter catches everything the second time, or even better, mix in about 1/4-1/3 cup of filter aid to each gallon of hot, unfiltered syrup. Then the filter aid is the filter. Then if you see fibers after that, they did not go thru the filter aid, the filter itself has been damaged and is shedding fibers.

[Michael Greer]

I bottle in glass jugs and fill to about 1/4" of the lip of the jug. They shrink down quite a bit, but still have a proper-looking level when cooled.

[KJamesJR]

I’m using the standard 12oz glass from Bascom. Kind of flat with the hoop. I have some folks in line to purchase some but I don’t want them to feel cheated.

I’m washing my filter with hot water from the tap. Until the water runs clear and the filter is mostly white again. I’ve never rung it out. I use black metal clips to air/drip dry.

[drewlamb]

And to your last question, I reuse containers all the time, including glass, so long as they're clean. Occasionally if I don't get perfect filtering, there will be a thin layer of fine nitre on the bottom of a container that is very difficult to clean. Certainly if that's the case I recycle them. Obviously make sure they're clean and think of the hot packing as a kind of disinfectant. Along with the vacuum effect maple flats mentioned, the high temp is primarily done to do a final kill of any microbes in syrup, container, or cap. Don't forget to tip your containers on their side for a few minutes while hot to sterilize the cap.

[Rangdale]

Maybe throw a pre-filter over your final filter? That should let the hot, filtered syrup flow right thru but would catch any stray fibers I would think

[Daveg]

You can re-use glass bottles and jars. You SHOULD NOT re-use caps or Mason-style lids (10¢ each).
I find it strange your fibers are floating. They should be dispersed throughout the syrup if they contaminated the sample through the filtering process making me think they entered your sample AFTER you bottled but before you capped or they were in the containers before you bottled. Is your bottling environment dusty? Are the containers "open" for long periods before filling?