Does Burying a Pot in Compost Create Patina?
When he was an apprentice here Andrew Robson puzzled over guidance we hear frequently: ‘Bury a new ceramic pot in compost and in a few months you’ll see patina on it’. Well, he took a new, unused pot and buried it in compost for fully two years. He watered it every day (true story). We just took it out, carefully washed it down, and here’s our results:
The difference is…drumroll…negligible. Or less. We actually could not identify any patina buildup whatsoever.
And here’s our pre- and post- photos of Andrew’s experiment:
Andrew took this pre-experiment photo of a new Roy Minarai pot, fresh from the kiln, before burying it in compost for exactly two years.
And this is after two years buried in nursery-bought compost. Granted, the lighting is a bit different making everything look yellower, but that’s deceptive. It’s just the bad lighting here with a warm bulb. The pot is also as shiny as the day it was made. In fact it’s eerily unchanged. There was a scant amount of residue on the inside, where the potter’s making marks held some of the dirt. But dirt is not patina, and there was no patina whatsoever visible on the glazed surface. Patina is the buildup of a residue that dulls the shininess of a pot, even changing the color of it to a more subtle hue, and is very desirable for making the pot look old. We didn’t see any of that. Although we can’t call this a myth on ‘one data point’, as Andrew says, we nevertheless remain unconvinced of the technique.
Just so we’re talking of the same thing…here are two images of VERY heavy patina buildup on old pots. These are over 100 years old. The actually glaze color of these is not a grayish cream, but the bright cream that is revealed in the scratch marks. So, we’re talking about residues that build up over a very long time, slowly, and they are quite durable (but can scratch! Hence in Japan, I was taught to be Very careful about repotting a tree in an old pot). Patina is not an acid that etches the surface (the glaze underneath is very shiny) and they are not lime buildups, which are white and are the result of hard water.
Scratches through the patina reveal the true glaze color, a light cream. The dark olive / gray over that is the patina buildup over decades. Most pots have nowhere near this amount of patina, but even a light buildup makes the pot dull, and infinitely more wabi-sabi. I’ve seen some lovely patina buildup in about 20 years; it’s a light wash but it’s there.
In this example the thick patina buildups have actually flaked off the bottom edge, causing it to reveal the light cream colored glaze underneath. These is NOT lime deposits, and though that is a common problem it is not generally referred to as patina.
Patina is a very valuable surface for a bonsai container, and yet in our first attempt to replicate it at a much faster speed, we utterly failed… But hope this clarifies what we were after in the first place. Pots with this surface are revered and highly valued and should be carefully handled.