I recently acquired a Presto pressure canner model 01781 (23-Quart) which comes with a weight designed to regulate it to 15 lbs of pressure. I also purchased a variable weight regulator (part 50332) which allows pressure to be 5, 10 or 15 lbs. After leafing through the recipes in the instructions I found that they are almost all invariably written with some odd pressure like 6 lbs or 11 lbs.
Can anyone explain how to achieve a stable pressure at one of these odd pressures? Why would the recipes provided all be written for pressures other than what this cooker is designed to produce? Should I simply can at the next highest pressure, e.g. 10 lbs if the recipe calls for 6?
I considered possibly adding a washer to the weight regulating at some in-between pressure but I'm just a bit confused about why I would even need to do that.