Bottles collapsing?

[GotSap?]

On several of my larger bottles (gallons and half gallons), the sides have collapsed some after the syrup has cooled, while the others have not. What causes this?

[happy thoughts]

The same thing that causes canning jars to seal. On cooling a vacuum is created so that pressure inside the container is less than the pressure outside of it. Guessing at the causes but you may have packed too hot, underfilled or your bottles were just very flimsy.

[red maples]

yep ...probably underfilled is my guess. 1/2 -3/4 inch head space is max really especially with larger bottles 1/2 gallon+ sizes. beacuse then as it cools there isn't much air to contract. The sugarhill bottles are a bit thinner plastic which I only had a problem with once. The Bacon jugs are stronger, and hold up better. especially when filling you don't get that bottom flex like the sugarhill jugs.

[GotSap?]

Underfilling is what I suspect, but if i fill a gallon jug (Bacon) enough to keep from collapsing, it seems to be a fair amount more than a gallon. I guess I'd rather have them a little overfilled and in shape than collapsed.

Thanks for the replies!

[Brent]

Gotsap
We used an accurate beaker to check our gallon jugs because our dealer tipped us off that they expand when hot packed and took more than the nominal volume.

Sure did. It took almost 1/4 quart extra. He says forget the gallon jugs. Sell two of the half gallons in glass at the gallon price and you make more without you customers thinking you're short changing them.

[TapME]

I wish that the bottle manufacturer would make the botlles hold the right volume in them. This has been a gripe I have had for years. I wonder if the juice you buy was sold in the same volume as these maple jugs. This is why I only pack in mason jars, they are the right measure. and yes I know thar syrup expands when hot, but 25% of the volume!!!!!

[michiganfarmer2]

they arent full enough. The air space contracts more than the liquid, and causes a vacuum

at least thats what I think

[Brent]

close but no prize. The liquid is not compressable. As the liquid contracts while cooling, the air bubble will expand.

[PerryW]

On several of my larger bottles (gallons and half gallons), the sides have collapsed some after the syrup has cooled, while the others have not. What causes this?

I always turn the plastic just upside down just after filling and capping, except the gallon jugs, which I lay on the sides. If you do lay any jugs on their sides for cooling, you need to flip them right side up after 5 or 10 minutes or they will develop a permanent dimple on the side.