my clay pot ignorance (and importance) - Orchid Board

VickiC · #1 03-03-2011, 11:52 AM

Hi everyone,
I plan to repot some orchids in the Spring and I want to use clay pots (for catts) with aeration holes in the sides as well as one on the bottom, of course. I have several 4" pots that I have bought locally and 2 6 1/2" pots from the same bigbox store. Other than that, there are no sources nearby. I would like some 5" (or so) pots. In the past when I have had to break a pot to remove an orchid, I have sometimes noticed that the inside layer is another material rather than clay....what, I don't know!?! Does anyone know if the fact that the entire pot is not clay make any difference in air flow? Is this actually important or am I making something out of nothing? I found a vendor online that I called to ask this question to and he didn't know.....same as me. By the way, he said that his clay pots have 3 side holes.

I would appreciate it if someone will advise me and comment if I'm being too picky or not. If you know of more sources that I can order from, I will appreciate knowing that, as well.
Vicki

Orchid126 · #2 03-03-2011, 03:28 PM

Did the "other" material look like it was painted on?

You can buy regular pots and drill holes into them if you had a good drill. Soak the pots first to prevent cracking.

ryrycochinco · #3 03-03-2011, 03:32 PM

maybe the outside of the pot was treated with a chemical sealer or stain, and your just seeing the untreated clay

neb · #4 03-03-2011, 08:39 PM

All of the material in the starts out the same. The difference is from when they fire the pots the outside layer color is from oxides that form. Since the oxygen only penetrates a little the middle stays the original color.

VickiC · #5 03-05-2011, 12:06 PM

I couldn't tell. All I could see was a layer of something between the inner and outer surfaces of the pot. That it's there is probably no big deal, and many of you probably think I'm being silly, but I was just wondering if it was the same situation with all clay orchid pots and that "middle" layer interfered with the clay pot breathing. I guess I must have a heavy watering hand (even though I try hard not to be) because root rot has been a problem for me in the past. I thought maybe there are clay pot "wanna-bes" which were inferior. By the way, my husband has drilled holes into them for me in the past, but he didn't really like to....but maybe I'll talk him into it again. Oh, and thanks for the tip....we didn't know to soak the pot first to prevent cracking.

Thanks for your reply,
Vicki

Quote:

Originally Posted by Orchid126

Did the "other" material look like it was painted on?

You can buy regular pots and drill holes into them if you had a good drill. Soak the pots first to prevent cracking.

VickiC · #6 03-05-2011, 12:17 PM

Ahh, good point. I never thought of that. I would have thoutht a "sealer" would prevent clay being breathable, but what do I know.....I'm the one asking the question.

.

Thanks for your reply,
Vicki

QUOTE=ryrycochinco;384054]maybe the outside of the pot was treated with a chemical sealer or stain, and your just seeing the untreated clay[/QUOTE]

britbloke · #7 03-05-2011, 12:23 PM

Most of the pots I get have that gray layer in the middle, occasionally I run across a couple that seem thinner and have no gray layer, but I don't experience any difference between them. The same BigBox store I have been buying 4.25" & 6.7" pots from has suddenly started carrying 5" pots. Not only a nice size but about 1/2 the price of even the smaller 4.25" pots.

I use an angle grinder to put four slits in my clay pots. The lower 1" of the sides and about 1/2" to 3/4" into the bottom. Much, much easier and quicker than trying to drill them...

VickiC · #8 03-05-2011, 12:24 PM

Thanks for your explanation. I'll mark my question off of my list of things I've been wondering about. As far as "breathability" goes, I need all the help I can get.

Thanks for your reply and again, your good explanation.
Vicki

Quote:

Originally Posted by neb

All of the material in the starts out the same. The difference is from when they fire the pots the outside layer color is from oxides that form. Since the oxygen only penetrates a little the middle stays the original color.

Ray · #9 03-05-2011, 01:30 PM

As Ned said, it has to to with oxidation state of the iron in the clay body.

If the firing is done with the stoichiometrically correct air/fuel ratio for complete combustion, the kiln atmosphere will not have "extra" oxygen, and the iron will be reduced, turning it gray.

Once the hot clay comes in contact with the outside atmosphere, the surface will oxidize (turning it the "orange" color we recognize), but the interior of the wall may- or may not, depending upon the temperature and porosity of the clay body.