Frost.....Proof?

[Sorcery]

I'm familiar with the tests as laid out on DigitalFire.com.

Seeking actual proof of things under 2% absorption surviving outdoors.

Open to all thoughts and comments.

I have some bonsai pots that are under 2%, they still ring nicely when struck, the ones that don't make me nervous, since they have broke.

Elder bonsai pot artists say one must guarantee pots Frost Proof, which I do and intend to continue to....

Looking on your take about how stressed that should make me, and any cautionary tales.

Say Hello to that Girl Tia!

Sorce

[Mark C.]

If the clay holds much  water after firing freezing will kill it outside. Just make sure you are using clay that  is under 2%. Seems straightforward .

[liambesaw]

If it thuds instead of rings I wouldn't trust it outdoors.  

I have oodles of outdoor pots, I can verify that under 2% absorption seems to do just fine 

[Magnolia Mud Research]

1 hour ago, Sorcery said:

I'm familiar with the tests as laid out on DigitalFire.com.

Seeking actual proof of things under 2% absorption surviving outdoors.

Open to all thoughts and comments.

I have some bonsai pots that are under 2%, they still ring nicely when struck, the ones that don't make me nervous, since they have broke.

Elder bonsai pot artists say one must guarantee pots Frost Proof, which I do and intend to continue to....

Looking on your take about how stressed that should make me, and any cautionary tales.

Val Cushing's book "Cushing's Handbook" has a section on the absorption for freezing conditions for fired stoneware.  

Keep in mind:  There are thousands of tons of ceramic roofing tiles and structural ceramic bricks that are used for buildings and housing in the areas where ice is normal in the winter and no ice the rest of the year.    The tiles and bricks  survive. 

If absorption is too much, the items will break, and if the absorption is too small, the items will break.  There is a region that is "just right".  

Look outside the studio art ceramics discipline,  brick and tile roofing technology would be a good starting point.  Also look in the ACerS Journals,  early and mid 20th century time frame. 

LT

[Min]

@Sorcery, have you done the open vs closed porosity test? Clay needs to be less than 0.78 (in products firing to more than 5% porosity) in order to pass CSA and ASTM specifications for outdoor use. A little anecdotal evidence that high porosity clay can survive freeze/thaw conditions if it has an open pore structure. I made several really large outdoor planters about 30 years ago, all of them are outdoors and unprotected year round. I made them with Fairey 78G clay and single fired them to cone 6. This is a really groggy cone 10 clay, at cone 8 it has a 10-12% absorption so even though I didn't measure it at the time I know at cone 6 it will be higher than that. We live in an area that can have many freeze/thaw cycles during the winter, none of the pots have cracked. There is a high amount of +35 grog in this body, walls of the pot are about 1/2 thick yet it can drain the water because of the open porosity of it. I'ld suggest doing the proper open vs closed porosity tests with your clay bodies and your firing conditions. Wouldn't go by the ring vs thud test alone.

[Sorcery]

2 hours ago, liambesaw said:

oodles of outdoor pots, I can verify that under 2% absorption seems to do just fine 

This is the type of verification of this "under 5%" that passes regardless of the...

1 hour ago, Min said:

0.78

Which I have tested on some, though I have been shooting for no absorption after 24hours, so I don't have to boil things.

I appreciate all the feedback!

I do have a couple things planted for tests this winter. That'll help me know know on a couple clays.

Sorce

[Min]

0.78 isn't an absorption figure its the target ratio for clays being less than that for closed vs open porosity.

Brick industry uses a figure of less than 5% regardless of open or closed porosity.

Example would be if you have a claybody that has a closed porosity of 2.5% and an open porosity of 2.75% then the math would be 2.5 divided by 2.75= 0.91 (rounded) so going by the ratio alone this would fail as an outdoor body as it is above 0.78  but since both closed and open porosity fall well below the 5% (open or closed) figure it would pass. 

Need to measure both open and closed porosity. Theory being that if there are capillary like tunnels within the claybody the expanding moisture has somewhere to go when it expands therefore won't crack the clay. Closed porosity can have some surface porosity but a tight vitrified body doesn't have the empty tunnels to allow expanding moisture to enter. The one scenario is why vitrified clay doesn't crack, other scenario is why bricks and roofing tiles don't. 

[neilestrick]

Also consider the form. If the soil is moist and freezes it needs to be able to expand, so the form shouldn't taper in at the top. Also no areas where water can puddle and freeze.

[LeeU]

Oh just ducky----it never crossed my mind (that being half gone anyway!) to concern myself w/absorbency regarding my plant markers!  

The stakes are 1"  x 7-8" length x 1" wide x  1/8-1/4" thick.  Glazed on front, unglazed sides & back. It did not occur to me to advise that people bring them in for the winter.  

The body is T6b,  listed to be .58%, fired to cone 5. They are being used in various U.S. locations and some are on their way to Europe. They  will be used outdoors and in soils that may freeze & may be left out over-winter in snow. .   Am I very likely going to have people experiencing breakage? In other word, should I contact people with a caution at this point or just let it go & pray?  If they contact me, I will make good on it of course.  The new body I plan on using is Rocky Mountain's Dover, absorption listed at +/- 1% . 

[Bill Kielb]

On 12/12/2020 at 12:27 PM, Magnolia Mud Research said:

There are thousands of tons of ceramic roofing tiles 

Waterproofing for clay tile roofs is in the underlayment. They do crack, leak and degrade in freeze thaw.. Not a bunch but they do. Picking the right underlayment forms the basis for your warrantee. Same is really applicable to cedar shakes as well.

[Sorcery]

15 hours ago, LeeU said:

-it never crossed my mind

(Tongue out emoji)

I brought it up slightly in my reply to one of those threads of yours, something about keeping the unglazed end at the top out of the water. 

I think 90% of people will "winter" them indoors. 

I only use clays said to be under 1% at maturity and haven't had a problem .... yet.

Sorce

[Min]

18 hours ago, LeeU said:

Am I very likely going to have people experiencing breakage?

Probably not. I agree with Sorce, I think most people would bring them in at the end of the season. At <1% absorption they should be fine. 

18 hours ago, LeeU said:

The new body I plan on using is Rocky Mountain's Dover, absorption listed at +/- 1% . 

I looked up this claybody, just to confirm it's this one right? Under the description it says it "fully vitrifies at cone 5, but will fire at cone 10 beautifully". And under the specs it has absorption at 1% +/- 1% but it doesn't say this is the figure for cone 5. I don't think it is, I think that is the absorption figure for cone 10. Before making a lot of plant markers with this claybody I'ld do your own weight absorption tests. (link here on how to do those if you need it, about 2/3rds the way down)

[LeeU]

8 hours ago, Min said:

o your own weight absorption tests

Thank you---I bet it is the percent for the high fire, and I will do the testing. 

[Sorcery]

11 hours ago, LeeU said:

bet it is the percent for the high fire

I've tested Amaco's #46 Buff vitreous from 6-10. Standards 101 is close, between hot 6 and 9.

I reckon everyone has their version of this wide range buff clay, Dover is probably their's.

Sorce

[oldlady]

lee, gardeners like to start each year with some kind of orderly disturbance of the soil in preparation for sowing seeds or setting out plants.   they have probably picked out the labels as part of winter clean-up.    so only worry about the few who might not have done so.

[Chilly]

On 12/14/2020 at 3:18 PM, Sorcery said:

I think 90% of people will "winter" them indoors.

Depends on what plants they are for, and where they are planted.

I have a couple of raised beds as herb gardens.  My herb labels live outdoors permanently, as do the herb plants themselves.

I also have labels in the soil by all my fruit trees and bushes, so I can remember which variety they are.

I'm not concerned with freeze/thaw, as one lot are fired to ^6, the other are copper labels, not ceramic.

Be prepared for some failures, although I doubt you'll get many.  I think the worst is when water sits in a hollow, not on/around a stick.  I made a ^04 door number that's been outdoors for 15 years and is fine.  I've also had ^6 plant saucers crack, in the greenhouse.  

Fingers crossed your labels will be fine.