Canning season is in high gear and we’ve received a lot of questions about selecting the proper lid for your canning jar. We’ve put together a basic guide that will help you determine the proper CT lid (continuous-thread lid) for your canning needs. Not sure what a continuous-thread lid is? A CT is the Mason-style closure mechanism where the jar and lid are both threaded in one continuous bead around the entire circumference of the opening; also referred to as “screw-on”. Both the 2-piece and the 1-piece canning lids will have a plastisol liner – a rubbery gasket that is attached to the lid.
Here’s some things you should consider when choosing a lid.
What are you preserving?
Find the recommendation for that type of product or combination of products. If you are selling your product, you will want to get in contact with your local Ag Extension office to see what additional guidelines or requirements are in place. These recommendations will help to determine what type of process(es) you will want to follow. The National Center for Home Food Preservation is also a good resource for general canning guidelines.
Which process will you use?
Your process may determine which type of jar and/or lid you use. (See the 3 basic processes below.) If you find that you have a choice of processing options, this may open the door for you to use something other than the traditional 2-piece lid. This may also give you the option to use a jar other than the traditional mason jar.
Once you determine your process, you may then have some other things to consider.
- If you are going to be in & out of your jar often, you may prefer to use a 1-piece lid.
- If you are selling or gifting, many folks leave the bands on so that the lid doesn’t get bumped off in transit. Using a 1-piece lid with a button is a nice option. The button will be an easy indicator that the seal is intact.
- If you are planning to enter your goods in a state sponsored fair or competition, they will likely require you to use the 2-piece lids. Check out Blue Ribbon Country Canning for some helpful timetables, tips and guidelines for safe canning in compliance with the USDA.
- If the person opening the jars has arthritis, you may want to consider sticking with the 2-piece. Sometimes, it’s easier on the hands & wrists to pop open a jar than to twist off a 1-piece lid.
For Hot Fill:
Preheat your jars (either in a large water bath or in the oven); and using a small sauce pan, preheat your lids in a simmering water for 5 – 10 minutes. Pour HOT contents into pre-heated jar, cap immediately with pre-heated lid. As soon as it is capped, the plastisol (already softened in the simmering bath) begins to form a seal around the rim of the jar. As the contents cool, the vacuum is created, the lid becomes concave. Whether or not you actually hear a “pop” will depend on the type of lid, but you should be able to tell visually if the lid has created enough vacuum and a seal. Some folks still feel the need to water bath these jars…which can affect the vacuum and cause them to NOT seal properly. Our CT jars and Lug jars are compatible with this method, so your lid choices will depend on the jar that you choose.
- Suggested lid: Standard plastisol
For Water Bath:
If product is already hot, the jar should be preheated as well to avoid thermal shock. The necessity, time, and temperature of preheating lids is subjective here depending on plastisol type, fill temperature and process time; again, consult your process authority. The standard plastisol lids are compatible with shorter water bath processing (such as hot-pack jams/jellies). Longer water bath process times may require the Hi-Heat plastisol.
It is important to follow the guidelines for your particular food as they can vary greatly.
- Suggested lid: Hi-Heat 1-Piece OR 2-Piece
For Pressure Canning:
Whether contents are raw or cooked, the jar should be preheated to avoid thermal shock. The need for preheating of lids is subjective as the heat created in the pressure canner will be sufficient to soften the plastisol and the temperatures in the canner are sufficient for any microorganisms present on the lid. It is important for these jars to vent properly, so be careful to not over-tighten.
- Suggested lid: Hi-Heat 1-Piece OR 2-Piece
REMEMBER: There are many variables that may impact your sealing rate. Whenever a process is performed by hand, there are variations. Here are a few things to consider as you preserve…whether you are starting out, or trying your hand at a new process, new foods or a different style of lid or jar.
- JAR QUALITY: Are your jar rims clean & smooth, crack-free and food safe?
- CONTENTS: Some foods contain more air than others; especially whole foods. It is important to follow guidelines for minimizing the “extra” air (trapped in foods OR bubbles from filling). Be sure you are heeding any specific guidelines for those particular foods.
- TEMPERATURES: Abide by temperature guidelines (for filling and/or water bathing) and make adjustments for altitude as needed.
- PRE-HEATING: Does your process recommend preheating of jars and/or lids?
- HEADSPACE: Have you allowed enough headspace for the proper expansion, clean venting and sufficient vacuum?
- PROPER LID: Are you using the recommended lid for your process?
- TIGHTNESS of LIDS: Only finger tighten…if your lids are too tight, they will not vent properly! Sometimes you will see the metal buckle (obvious failure) or sometimes the seal is compromised…which you may not see, but still causes seal failure.
Compatibility of jars and closures with product and process is the responsibility of the user. Please consult your process authority and test packaging components for suitability.