Is this a glaze?

[CactusPots]

I made a trip to Tucson Arizona last week to visit some friends, the Gem and Mineral Show and sell a couple of boxes of pots to a cactus and succulent nursery there.  The owner of the nursery showed me this pot and told me how much he liked it.  In cactus and succulent show presentation, like bonsai, the pot is frequently understated not to detract from the plant.  This finish looks for all the world to me like it was rolled in sand when either the clay or something else was wet.  I've got several options and tests in the next kiln load.

Any opinions or advice?

[liambesaw]

Looks like sandstone!  Maybe a heavily grogged slip wiped back at leather hard?

[CactusPots]

Looks exactly like sandstone and feels like 60 grit sandpaper.  Very even application.  Wouldn't wiping it back at leather hard tend to push the sand particles down, kind of like burnishing?

[liambesaw]

12 minutes ago, CactusPots said:

Looks exactly like sandstone and feels like 60 grit sandpaper.  Very even application.  Wouldn't wiping it back at leather hard tend to push the sand particles down, kind of like burnishing?

It would bring out the grog, don't burnish, just wipe with a wet sponge. Or even spray it off if you have a spray gun + compressor.  Just fill your spray gun with water and hit it at an angle maybe?  

[neilestrick]

I've seen glazes similar to that. They're melted just enough to get them to fuse to the clay, but not form glass.

[Magnolia Mud Research]

I would try adding 60 grit sand to a clear glaze and see what happens.

[liambesaw]

Looking at it again, it looks like maybe glue or epoxy, you can see a white margin at then bottom that fades back to a third color at the foot.

[CactusPots]

I think that white fade is the typical hard water deposits we get in the water challenged southwest.  I water my collection exclusively with collected rain water to minimize this.

I'm pretty sure it's fired on.  There are little iron spots and white glass (?) bubbles.  I can't tell from my picture if it's grog or sand.  My opinion when I was looking at the pot was sand.  I think the main question is whether the sand should be applied separately, after the glaze or slip or should be part of the wet mix.  I'm thinking now it should be mixed in some kind of glaze and dipped to get the super uniform application.  Sifting the sand onto the pot after it's glazed won't be that uniform.  Whatever glaze I can use, it has to add pretty much no surface to the final pot.  Simple is always complicated. 

[oldlady]

any way to find out who made it and ask how it was done?

[Magnolia Mud Research]

1 hour ago, CactusPots said:

I'm pretty sure it's fired on.  There are little iron spots and white glass (?) bubbles

Are these and/or your pots fired to maturity or to a semi-maturity?

iI have been using dry clay powder to wet green ware  for surface texture, using dry sand might also work, if you are interested in the not so smooth texture.

LT

 

 

 

[Babs]

White fade caused by watering plant in pot you write.

Has this pot had a plant in it?

Was the "sand" totally adhered to the surface?

[Rae Reich]

Is that surface only on the outside?

I would coat a leather-hard piece with a thick coat of slip, then place upside down in a tray and pour/press construction sand into the slip. Brush off excess sand when dry. 

I think mixing sand with glaze will make it too shiny.

[Callie Beller Diesel]

If it’s got glassy bits in it, it might be something like chick grit or decomposed granite. 

[CactusPots]

I do think the pot had been used.

The sand is tight on the pot, no amount of handling will cause sand to come off.

The sand is on the outside and halfway down the inner wall, not on the bottom.  I usually glaze my pots with the rim glazed down to were the soil level would be.  No need for glazed interior.  Could be dipped, single drain hole makes a nice handle.

The other other weird clue I noticed about the pot was that it was obviously a thrown pot, but the bottom texture was canvas imprint, not a wire mark.   No feet, flat bottom.   This might not be significant.

I'm thinking some version of Rae's suggestion.  That was my initial thinking of the application.  Question is how to apply the slip, not so thick, single layer of sand.  maybe with something to delay drying?  I couldn't see any evidence of a slip layer, only the body and the sand.  I'm also trying a shino as the binding agent.

I've actually got some very red sand supposedly from Sahara that I'm trying now.  Where I live I have a really nice decomposed granite that I screen for soil mixture for cactus.  I did try a melt test on it once screened to 80 grit and it melts nicely to a mat black all by itself.  Lots of ideas for material, questions about application.

[Min]

35 minutes ago, CactusPots said:

The other other weird clue I noticed about the pot was that it was obviously a thrown pot, but the bottom texture was canvas imprint, not a wire mark.   No feet, flat bottom.

My guess would be it was thrown on a canvas batt then the canvas peeled off when pot is leatherhard.

Do you have a compressor? I'ld be looking at spraying a very sandy slip onto the leatherhard pot using the kind of sprayer they use for exterior textured walls. Just the same claybody the pot is made with plus silica sand.

[CactusPots]

Yes, I do have a compressor.  I think I still have a sand blasting gun also, maybe try that.

I've never heard of a canvas bat.  Doesn't seem like the canvas would stay on the wheel head.

[liambesaw]

35 minutes ago, CactusPots said:

Yes, I do have a compressor.  I think I still have a sand blasting gun also, maybe try that.

I've never heard of a canvas bat.  Doesn't seem like the canvas would stay on the wheel head.

You put a little slip or clay under it, kind of like a felt bat

[Magnolia Mud Research]

Checkout the document for canvas bats on Vince Pitelka’s website www.vincepitelka.com 

[CactusPots]

 

Here's  the first try, rolling in sand with wet shino.  Different,  I think I'm on to something I can use here.

[Joseph Fireborn]

To me it just looks like someone wedged sand, grog and chicken grit into the clay and fired it like that. I have made results when I was testing clay to look very similar.

[CactusPots]

Yikes!  Have you ever thrown Peter King clay?  That's what you'd have if you tried throwing a clay that had this kind of "tooth".   Take your fingerprints off for sure.

[Joseph Fireborn]

On 2/17/2020 at 10:01 AM, CactusPots said:

Yikes!  Have you ever thrown Peter King clay?  That's what you'd have if you tried throwing a clay that had this kind of "tooth".   Take your fingerprints off for sure.

No I haven't, but I throw clay with course grog, chicken grit and sand. It just takes a different approach.

Did you ever figure this out?

[CactusPots]

I threw the peep holes for my kiln from Peter King.  As far as I'm concerned it's un-throwable.  It's 10x worse than Soldate 30 as I recall.  But an excellent, low shrinkage architectural clay.  I highly recommend Peter King's book on the subject. 

[CactusPots]

Second effort.  I tried dipping the pots in the same slip as the thrown pot.  I did both bisqued and bone dry.  Then covered in sand.  The big problem was that the slip and sand did not stay on the pot well.  Needs some kind of flux to continue with the slip approach.  Looked good going into the kiln.  I like the sand mix of white sand blast sand, red sand and black grog.

What I need now is something that will adhere the sand to the pot and not add any color.  It would be a plus if I could glaze and add sand bone dry, but most of the kiln load will be bisque, so adding a line of work that is once fire does add a complication.  Next fire, I'll try some different liner type glazes, I think.  Shino worked great but adds a red base color I don't need.  I do have a super white shino from Coleman that I'll try as well.

[oldlady]

if it is only wanted on the exterior, why not try the same thing you just said but put the pot on a wheel with a giffin grip and use a red sherril rib to press it into the surface.   it would be done at leather hard after trimming the bottom.   no scraping off your skin.