Seals on glass bottles keep leaking

[javahill]

We bottle in 500 ml glass Folia bottles, which look great after we nailed the clarity issues. Customers love the bottles and we can charge more than enough to cover the price difference over plastic bottles. But we've been having problems with leakage as the sap cools. We can at 180 degrees and preheat the bottles in a hot water bath. We've always had some issues with leakage, but this year has been especially bad.

I've noticed that if I fill a bottle to the top, when it cools, the syrup has contracted about an inch down the neck of the bottle.

Hypothesis 1: I need to leave more headspace (air gap) rather than less. How much headspace should we leave at the top of the bottle?
Hypothesis 2: Bottle at a cooler temperature to reduce contraction of the syrup so the vacuum isn't strong enough to break the seal.
Hypothesis 3: Plastic screw-on caps suck. Just get used to recanning a lot.

Anything else? How have you beaten the leaking glass bottle problem?

[Big_Eddy]

We've always had some issues with leakage, but this year has been especially bad.

I've noticed that if I fill a bottle to the top, when it cools, the syrup has contracted about an inch down the neck of the bottle.

Hypothesis 1: I need to leave more headspace (air gap) rather than less. How much headspace should we leave at the top of the bottle?
Hypothesis 2: Bottle at a cooler temperature to reduce contraction of the syrup so the vacuum isn't strong enough to break the seal.
Hypothesis 3: Plastic screw-on caps suck. Just get used to recanning a lot.

Anything else? How have you beaten the leaking glass bottle problem?

Define leakage.

• You lay them down to sterilize the cap and there is syrup all over the counter?
• The bottle was full when you capped it, now it doesn't look full?
• You can see/hear air leaking into the bottle?

Syrup shrinks when it cools. The hotter the syrup when it goes in, the more it will shrink. The air above the syrup will expand to fill the gap, creating the vacuum you want to keep the lid sealed but making it look less full.

I'm not using the folia bottles, but my experience has been that 1 in 50 lids will leak when first tightened. When the bottles are laying down, I see the leaks as a trail of small bubbles moving from the lid to the air space. Stand it up, give it a quarter turn, and lay it back down - the leak is gone. Very rarely I will have a lid "pop" from overtightening once hot. Toss it and replace.

[happy thoughts]

What Big_eddy said but also re your Hypothesis 2: "Bottle at a cooler temperature to reduce contraction of the syrup so the vacuum isn't strong enough to break the seal."

180*F is the minimum temp recommended for a good seal and longer keeping qualities. That temp is measured in the bottle when the cap goes on not the temp in the pan as syrup will cool slightly on transfer. You may find you get a better seal (better vacuum) if you heat the syrup a little higher to say 185-ish* before pouring.

[happy thoughts]

One other thing assuming your definition of leakage is syrup that's actually leaking out of the bottle and not just the normal shrinkage you're seeing. Are you wiping the tops of the bottles before capping to remove any spilled syrup? If not, you should because a clean glass to cap contact surface is needed for proper sealing.

[javahill]

Thanks for your advice. I made two changes - wipe the top of the bottle before putting on the cap and snugging the cap down after it has been on a couple minutes. Today, there were no leaks.

[delivron]

I trust you allow the cap to contact the hot syrup after tightening down the lid and you are using the proper cap not one designed for induction sealing. If it is an induction seal then invest in the induction sealer to get a good tight seal.

[Indiana-Jones]

I had the same problem in the past with the black plastic caps leaking. Some appear to have melted a bit and slipped the threads. I started using metal caps and the problem stopped. This year I ordered caps and bottles from two different places. The caps came from http://sugarbushsupplies.com/ and bottles from SKS.

Good Luck

[javahill]

Just caps sold with the Folia bottles - white plastic. How would I tell if they were designed for induction?

[Super Sapper]

I have been having an issue with my quart bottle seals leaking. I use decantor bottles for quarts and pints and the same caps for each but only have problems with the quarts. On the ones that do hold their seal there is a loud pop when you break the seal and it gets sucked down into the syrup. I am getting about 15% failure rate on the quarts and none on the pints. To be honest the I am more carefule of wiping the rim on the quarts than the pints.