It’s a very simple solution to a problem that pops up just often enough to be annoying.
This is the problem of the broken or misfit lid.
Like I said… annoying.
I generally limit my lids to just a few sizes to minimize the confusion but, for whatever reason, sometimes things don’t work out as planned.
A quick note for non-mudheads… Clay shrinks as it dries. With some types of clay it shrinks just a bit, (it’s still a fairly noticeable bit though), sometimes it’s quite a bit… and when work is fired in the kiln, it shrinks a lot! So pulling a measurement straight off a dried or fired piece of work can be problematic.
My fall back plan is the “Clay Ruler”.
This is a clay slab impressed with a ruler with its measurement markings raised. As the slab dries to bone-dry, it shrinks.
Now when I take a measurement with my calipers on the opening of a bone-dry green ware canister, I can get the measurement directly from my clay ruler.
Both are already shrunk so there is no guesswork math, I just note the measurement on my shrunken ruler and readjust my calipers using a regular ruler...
and throw a new lid.
(If you want to see my lid throwing process, click here...)
No problem… I throw a set of 3, bracketing a hair up and a hair down just to hedge my bets. Usually one of the three works out to be a perfect fit.
Now like I said, each type of clay body shrinks different amounts, so I’ve got different clay rulers for each clay body I use. I also have clay rulers that have been fired as well. A set of bisque fired rulers, and a set of rulers fired to cone 6 and cone 10.
As the old saying goes… He who dies with the most tools wins.