Plastisol lined closures have struck a nerve with veteran and novice canners alike. Whether it's the promise of a smoother process, thanks to one-piece lids or the fascination with state-of-the-art sealing technology, plastisol is a hot topic. Come along as I explore the mystery and functionality of plastisol closures.
A quick refresher For the newbies in the crowd, plastisol closures are metal lids lined with PVC along the perimeter. These closures can be matched with glass jars to create a tamper-evident, vacuum seal. The process occurs as the solid plastisol material is melted (through heat transference from the product in the glass jar, no lid pre-heating necessary) and eventually cools along the landing of the glass jar, in turn creating the vacuum seal.
Real world application Meet Canning Carl. He's ready to make some of his world famous (at least that's what his mom says) strawberry jam. Previous canning posts explain the two canning methods, boiling water canning (recommended processing for high-acid food) and pressure canning (recommended processing for low-acid food). Strawberries and most other fruit are high-acid products. This means Carl should process his jam via the boiling water method. Though this isn't his first canning rodeo, he's never matched his glass jars with plastisol closures before. Where should he start? We'll catch up with Carl later.
To boiling water bath, or not to boiling water bath? An extensive discussion took place in the comments of our previous post on plastisol regarding the exact use of these lids. We know they're meant to form a seal with glass jars, but under what conditions? Are plastisol closures designed to be used in both boiling water canning and pressure canning processes? Maybe it's an either or situation, or maybe they aren't suitable for any type of processing. Whatever the definitive answer is, it's about time we've got to the bottom of this issue.
A message from the master of canning ceremonies I'm sick of the guesswork, aren't you? Numbers don't lie, so let's check them out. A boiling water canner functions at water's boiling point, 212 F. The boiling point in pressure canners is much higher. The question we seek to answer is whether or not plastisol can take the heat.
Plastisol lids can be used in canning, but it's important that you match your glass jars with the right lid for your desired process. For example, plastisol continuous thread lids should only be used in hot-fill (method that doesn't require any processing) canning. Lug/Twist caps are the closures you're after if you are looking to preserve food through boiling water canning. And finally, if pressure canning is on your agenda you're going to need a special high heat liner for that task.
The verdict The final judgment has been revealed! Glass jars and plastisol closures can take the heat! In levels, that is.
1. Continuous thread closures are able to sustain their form and function through hot fill procedures. 2. Lug/Twist caps stand firm under the piping hot conditions of boiling water canning (hot bath) processes. 3. High heat liners can tolerate the hottest of the hot, the pressure canning experience.
Putting all the pieces together... It's a good day. You learned something new and Helen the homemaker can now get to business (using lug/twist plastisol closures). Take pleasure in knowing that you're now equipped to use a variety of different plastisol closures through vastly different processes.
A quick refresher For the newbies in the crowd, plastisol closures are metal lids lined with PVC along the perimeter. These closures can be matched with glass jars to create a tamper-evident, vacuum seal. The process occurs as the solid plastisol material is melted (through heat transference from the product in the glass jar, no lid pre-heating necessary) and eventually cools along the landing of the glass jar, in turn creating the vacuum seal.
Real world application Meet Canning Carl. He's ready to make some of his world famous (at least that's what his mom says) strawberry jam. Previous canning posts explain the two canning methods, boiling water canning (recommended processing for high-acid food) and pressure canning (recommended processing for low-acid food). Strawberries and most other fruit are high-acid products. This means Carl should process his jam via the boiling water method. Though this isn't his first canning rodeo, he's never matched his glass jars with plastisol closures before. Where should he start? We'll catch up with Carl later.
To boiling water bath, or not to boiling water bath? An extensive discussion took place in the comments of our previous post on plastisol regarding the exact use of these lids. We know they're meant to form a seal with glass jars, but under what conditions? Are plastisol closures designed to be used in both boiling water canning and pressure canning processes? Maybe it's an either or situation, or maybe they aren't suitable for any type of processing. Whatever the definitive answer is, it's about time we've got to the bottom of this issue.
A message from the master of canning ceremonies I'm sick of the guesswork, aren't you? Numbers don't lie, so let's check them out. A boiling water canner functions at water's boiling point, 212 F. The boiling point in pressure canners is much higher. The question we seek to answer is whether or not plastisol can take the heat.
Plastisol lids can be used in canning, but it's important that you match your glass jars with the right lid for your desired process. For example, plastisol continuous thread lids should only be used in hot-fill (method that doesn't require any processing) canning. Lug/Twist caps are the closures you're after if you are looking to preserve food through boiling water canning. And finally, if pressure canning is on your agenda you're going to need a special high heat liner for that task.
The verdict The final judgment has been revealed! Glass jars and plastisol closures can take the heat! In levels, that is.
1. Continuous thread closures are able to sustain their form and function through hot fill procedures. 2. Lug/Twist caps stand firm under the piping hot conditions of boiling water canning (hot bath) processes. 3. High heat liners can tolerate the hottest of the hot, the pressure canning experience.
Putting all the pieces together... It's a good day. You learned something new and Helen the homemaker can now get to business (using lug/twist plastisol closures). Take pleasure in knowing that you're now equipped to use a variety of different plastisol closures through vastly different processes.
About the Author:
Glass jars make great product packaging. Read Kayla Holman's blog on using glass jars and plastisol lids for home canning projects.
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