It finally makes sense.
For years, I’ve been speculating about exactly what the numbers on the rim of Presto’s cast-aluminum pressure canners actually mean. I now have what I believe to be confirmation.
On the rim of the Presto-made cast-aluminum canners there’s a series of three two-digit numbers as show here:
![1969 Sears Presto Canner Markings, close-up](https://cookingwithjim.com/wp-content/uploads/2018/08/searsprestopressurecannerdatecodecloseup.jpg)
Or here:
![1971 21-B Presto Canner Markings](https://cookingwithjim.com/wp-content/uploads/2012/05/presto-21b-canner-open-close-closeup.jpg)
I was sure that these markings meant something – Presto wouldn’t have gone through the trouble otherwise, right?
The first set of markings always made complete sense. The 21-B is a 21 quart canner, and my Sears is a 16 quart. Having the canner bottoms labeled as such made perfect sense.
The last number being a year also made sense to me, but I figured could have been open to some interpretation. There are references out there on parts websites, for example, that refer to parts for the cast-aluminum canners as “made in 1971 or before”. I always thought that my 21-B pictured above would have been one of the last cast-aluminum canners Presto made. I did wonder if I was correct or not.
I didn’t have any idea what the middle number could be. Several years ago I had asked in an online canning group and they suggested it could be a week of manufacture. While this made some sense to me, I had a 1967 canner bottom that had a middle number of 51. I wondered if the factory was working right up until Christmas that year. I now think they were.
In 2018, I walked into a local Goodwill and found a Sears-badged cast-aluminum Presto canner. It was in great shape, had what I have no reason to doubt was the original manual, and I didn’t need ANOTHER canner, so I brought it home anyway. I scanned in the manual, did a blog post about it, and went on with my life.
Enter 2021.
I ran across the paper manual and picked it up, asking myself, “did I ever scan this one?” While I was paging through it I noticed this gem:
![Handwritten note in the manual of my 1969 Sears Presto Canner that confirms my dating theory.](https://cookingwithjim.com/wp-content/uploads/2021/01/1969-handwitten-note-Sears-Presto-canner-1024x281.png)
This canner has “16 14 69” on its rim. It’s a 16 quart. The manual has a copyright date of 1968. This handwritten note would likely be the date the previous owner bought it – 6-15-69.
If the “14” really is the week of manufacture, that would mean that the foundry cast this particular canner after the Easter weekend in 1968. I think it not only likely, but entirely plausible that a canner produced just after Easter in 1969 could have made it into someones hands by canning season in June.
Mystery solved.
I have a 21-B canner and bought the suggested replacement petcock 9978 but it doesn’t fit on top of the pipe vent (the hole on the weight seems too small). Do you recommend the 3 weight set or this one from Amazon Univen Pressure Cooker Canner Regulator Weight Replaces Presto 9913/9978?
Melissa,
I’d recommend replacing the vent tube with a 1058 and getting the three piece weight set for it. That’s what I have on all mine.
Jim
I am still using this same canner that was my mom’s. No numbers on mine that I can see. Only the “open” and “closed” writing. I have replaced seal several times and have to soak them good before each use and it’s a bit tough to twist open and shut but other than that, it is still going strong! Thanks for the information as I was on here looking for how old this thing is!
Erin,
Applying some petroleum jelly to the lugs on the lid and bottom where they rub together may help with that tough-to-twist lid.
Jim
I like your theory, but I have a Presto 7av that’s 16 quarts while the number on the rim is 21 34 60. 😕 Any ideas?
Bridget,
How tall is it? Could you stack two pint jars on top of each other in it?
Jim
Thanks for scanning in the man. I have a 620.46000 that was my grandmothers, used it today to can some pears.
David,
You are very welcome!
Jim