Inside a glazed pot

[cuwire]

I have heard 3 reasons why a bonsai pot - glazed on the outside should not be glazed on the inside.

The tree speaking.

1. The unglazed surface allows the plant to breath.
2. The unglazed surface allows the roots some grip.
3. Just does not feel right putting a tree into a glazed surface.

The pot speaking.

1. The inside glaze and pattern will detract from the outside when displayed for sale.
2. Why wast glaze if you are not going to see it.
3. Glaze will run out the bottom holes and spoil the kiln shelf.

What do you think?

Cheers David

[Joel]

Or you could go about it in the opposite way. What is one reason FOR glazing the inside? Are there any benefits?

Joel

[PaulC]

Hi David/ Joel,

I drafted this reply right after I saw David`s post, but refraind from posting it.

But Joel, seems you have asked a similar question to me, so thought I would post my thoughts.

David, Interesting topic, and thanks for raising it.

My first reaction was , well what about plastic pots ?

They would be the same as internally glazed pots, surely?

Perhaps there is not as much insulation against heat and cold as a glazed pot,
both internally, and externally, but are still waterproof, and smooth.

Which got me thinking.............

Obviously there is drainage required in any pot, plastic, glazed or otherwise.

Would the internal of a bonsai pot give any added benefit from being unglazed internally, yet externally ?

Sure there are lots of terracotta pots that are unglazed both in and out, but these do tend to be pourous.

I have noticed that my bonsai pots which are unglazed both internally and externally do not seem to be as pourous, if at all ?

I can only presume this is the quality of the clay ?

As for the pot speaking, I can see the practicality of the second and third points, but oddly enough I have noticed a trend toward everyday items being decorated internally.

My thoughts turn to clothing.

Look at the insides of shirts, and shoes, ( mainly womens ), manufacturers seem to want to contrast or add to the products appeal at any length, even though the articles interior will not be seen.

Thus not only standing out from other product, but obviously draw their item/s, and the consumer away from the next product on offer by adding a little added extra or appeal.

So I am wondering, has there been any pots produced with internal glaze only, yet an unglazed exterior ?

Or even both, yet in different colours ?

Rgards,


Paul.

[cuwire]

Yes Joel I think your point is right on the money.
Paul lots of interesting observations I wonder if a potter might contemplate decorating at least some of the inside - would look good on the shelf?
Paul earthenware is a clay fired at a "low" temperature and is typically your common garden pot. Bonsai pots are for the most part made from a clay type referred to as stoneware and is fired at a higher temperature and becomes more glass like and therefore water proof and stronger.

Still -- the first 2 points are the only ones I have heard before from bonsai enthusiasts and I wonder if they hold any substance.

Cheers David

[PaulC]

Hi everyone,

was just looking at the thread on when is a tree ready for a pot, and noticed something Bretts had posted.

[quote](As to the Japanese using bonsai pots for cuttings and the like, I think they use ordinary round clay pots mostly. It may have something to do with the price, or that they are porous and that it rains a lot over there and these pots help with keeping the roots less soaked.)

Seems an interesting point as well, as in regards to the amount of rain that is received in Japan.

Perhaps the insides of the pots are not glazed for this reason as well, for paracticallity as well as ecomonic reasons

Thanks Bretts for giving me even more to contemplate about this subject !!


Regards,


Paul.

[PaulC]

Just realised that I posted the wrong user for the quote on the pots.

The quote was from Handy Mick, not Bretts.

My appologies to both of you.

Paul

[Roger]

David
Good questions.
Here are some thoughts from a sometime potter:

The tree speaking.

1. The unglazed surface allows the plant to breath.
As said already, breathing by the pot depends on the temperature to which it was fired. Earthenware (low temp) does breath and soil will dry out noticeably in warm and windy weather. Stoneware (higher temp) is glassy and virtually doesn't breath as might be noticed by bonsai or bonsaiits. And yes, comparison with plastic pots for this characteristic is good.
2. The unglazed surface allows the roots some grip.
I haven't seen it tested, so can't really say.
3. Just does not feel right putting a tree into a glazed surface.
feelings are feelings.

The pot speaking.

1. The inside glaze and pattern will detract from the outside when displayed for sale.
Depends on how well it is done and on the individual buyer. Some will like it and some won't.
2. Why wast glaze if you are not going to see it.
This was certainly one of the issues put to us at pottery school. If you are paying a lot for expensive glaze materials, it is generally a waste if they are not going to be seen. However, glaze is generally at least carried over the lip of the pot so that the differently coloured clay is not visible when the pot is used for it's intended purpose. In a bonsai pot, it looks strange to see a nicely glazed exterior of a pot and then the clay showing on the inside because the 'soil'/'mulch' etc doesn't reach to the lip. I extend the oxide colours of the outside of my pot into the whole of the interior so that the whole of the pot looks good and integrated.
3. Glaze will run out the bottom holes and spoil the kiln shelf.
Not really an issue for a good potter. The same issue applies to the outside, and there are various techniques potters use to prevent this.

I personally think it doesn't make much difference to the plants whether the inside is glazed or not. It may be a positive or negative factor for the buyer/user, as well as the maker.

Cheers
Roger