The canning season is in high gear and we have received many questions about choosing the right cover for your canning.
We have put a basic guide that will help you determine the correct CT cover (continuous line cover) for your can needs.
Do not know what is a continuous line cover? CT is a Mason type sealing mechanism. The tank and cover are open around the whole circumference of a continuous bead thread;
Also known as "screw on". Both the two-piece and one-piece can caps will have a plastisol pad - a rubber gasket attached to the cap.
Here are some things you should consider when choosing a lid.
1. 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.
2. 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.
1. If you are going to be in & out of your jar often, you may prefer to use a 1-piece lid.
2. 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.
3. 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.
4. 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 saucepan, preheat your lids in a simmering water for 5 – 10 minutes.
Pour HOT contents into the pre-heated jar, cap immediately with a 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.
For Water Bath:
If the 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,
onsult 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.
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.
What impacts your canning lid sealing rate?
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.
1. JAR QUALITY: Are your jar rims clean & smooth, crack-free and food safe?
2. 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.
3. TEMPERATURES: Abide by temperature guidelines (for filling and/or water bathing) and make adjustments for altitude as needed.
4. PRE-HEATING: Does your process recommend preheating of jars and/or lids?
5. HEADSPACE: Have you allowed enough headspace for the proper expansion, clean venting and sufficient vacuum?
6. PROPER LID: Are you using the recommended lid for your process?
7. 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