Short clay

[Babs]

The ladt tonne of clay I bought, red clay fires as high as c4-5 with a loss of the typical terracotta red, but I dont mind that.

It Is very short, handle making a nightmare. I add a splosh of vinegar to my throwing water and handle making which helps a bit. Company says no other complaint ...hmmm,

Any way let me know how you'd tackle this. I have an ancient Shimpo pugmill. I encorporatr the throwing slop.

So unbag, pug with bentonite or what?ad vinegar there too

[Hulk]

Wonder if Nerd's fixit would help?
I'll add maybe a quarter cup to three gallons of reclaim slop at mix/blend with the grout mixer stage. It doesn't take much to make a noticeable difference.
If I remember correct, it's eight parts OM4, one part silica, one part feldspar.
A bit more plastic, more slip-pery, takes longer to dry, feels nicer. I'm sure it can be overdone, heh.

[Babs]

OM4 a ball clay?

Got a few ball clays random ancient ones

 

So there you are! Got ball clay F .

So will play. 

Thanks @Hulk

[Hulk]

Didn't find the og post right away.

Here's from a thread that had it copied though:

"This is from GlazeNerd's comments on this forum awhile back...

Additive for Reclaim Clay
How do you determine the level of ball clay the recipe had to begin with?    The Slip Test

When you throw the original clay: how much slip comes up and on your hands?

Coats just the inside of your palms and oozes through your fingers over time.... lower levels.

Coats your palms, and oozes; have to clean a few time while throwing.... mid levels

Oozes quickly and constantly cleaning off hands....... high levels.

Most of the reclaimed scraps is from trimming; which has been stripped of the fines; which includes ball clay, silica, and feldspar. That would alter the properties of recycled clay: because it is the ball clay primarily that holds moisture in a clay body.

The fix:  blend 80% ball clay (Om4 or FHC), 10% silica, and 10% feldspar. Add 1 cup (dry) per gallon of slurry. The testing comes when you throw it after it has been reclaimed: how much slip comes up when you throw? Adjust to suit your taste.

Normally within 30 days there is a marked difference, which improves over the next 90-120 days. After about 6-8 months, the process begins to reverse because the clay is actually starting to loose water: dehydration."

[Babs]

Thanks @Hulk.

Annoying to have to do this with clay fresh out of the bag, but.

[C.Banks]

I remember helping a short clay with vee gum.

It was only a couple of weeks old and I was impatient. It worked well but I don't remember how little I used. It wouldn't have more than few percent or less.

I do remember it being expensive.

Hawthorn bond seemed to help surprisingly well once too and it was only something like 6%. *never mind all this I forgot you are at cone 5.

Edited September 4, 2022 by C.Banks

[Pres]

When working with short clay at the HS, which happened a few times, I would resort to older clay. I used to keep barrels of slop or pugged clay over the Summer. When the new clay came in one of the first things on my list was to throw with it. Long before the students would be using it, actually before they started school. If the clay was short, I would divide out the first 1000# and start pugging. . . half and half, half from the barrels, and half from the new boxes. The clay would be ready to use by the time I had finished my intros, and they had completed a series of wedging and pinch pot exercises. The rest of the clay would be fine by the second semester of school.

 

best,

Pres

[Min]

15 hours ago, Babs said:

Company says no other complaint ...hmmm

I don't think it's reasonable for you to have to fix a ton of unworkable short clay. I would show them it's short; roll out some coils about the thickness of a pencil and bend it around your finger, if it cracks badly it's short. Make a 1/4" thick slab and bend it at right angles and look for cracks. Take some photos and email them, offer to send them a sample. Take photos of the batch numbers on the boxes. Let them know it's unacceptable to work with and ask them what their solution is.

[Babs]

6 hours ago, Min said:

I don't think it's reasonable for you to have to fix a ton of unworkable short clay. I would show them it's short; roll out some coils about the thickness of a pencil and bend it around your finger, if it cracks badly it's short. Make a 1/4" thick slab and bend it at right angles and look for cracks. Take some photos and email them, offer to send them a sample. Take photos of the batch numbers on the boxes. Let them know it's unacceptable to work with and ask them what their solution is.

Thanks Min, I live on an Island, freight and fuel a bummer, I've fought in the past when huge chunks was in their fine throwing clay...filter blew out but to return about 10 yrs ago was over $200 freight each way.

Sorry for the moans, have done some bags re@Pres just extra disappointing labour for an aging body.

Was seriously thinking no more reclaiming, just spread over sandy paddocks..

 

Will send the photos to them . It may jolt them into action. It comes from a working pottery so their potters, garden pots and such ware, will have moaned and got it sorted I am sure.

Not sure how important the selling of their clay is in their business finances.

Any way, no miracle cure, will also try Nerd's stuff.

Think the vinegar just eases the surface.

[Min]

Not to sound cynical but perhaps they sold it to you knowing it would be difficult to return. Doesn’t seem fair that you should pay shipping to return goods that are not up to standards.

[Pres]

@Babs, In the day, I had enough energy, today it would be a chore. I often had students help with moving/reclaiming and storing the clay. We would start the year with a fireman's line passing boxes from person to person til we had it all stacked in the room. I was the first to pass, as I lifted off of the pallet and passed it to the first student. Doorway was too narrow for pallet, and we had no carts, besides this was faster and took up a little class time with exercise. Doubt if I could move a ton with them that way now days.

 

best,

Pres 

[Babs]

54 minutes ago, Min said:

Not to sound cynical but perhaps they sold it to you knowing it would be difficult to return. Doesn’t seem fair that you should pay shipping to return goods that are not up to standards.

Yip, my thoughts exactly. And 2x made me more convinced about it.

Doc told me to work out because of bone density. What a joke!!

He's the one I should be sending photos to:-))))

Anyway I'll keep that in mind when I pug and pack, dammitttt.

Sense of ironic humour helps most things

 

[Kelly in AK]

A ton of short clay, that’s a lot. I definitely understand the shipping situation though.

I’ve used Epsom salt with my local clay which is short and thixotropic. It made a noticeable difference, but not as much as I needed. Veegum is what I settled on. 1-1/2% allows me to throw it reasonably thin, which was impossible before. It has to be thoroughly mixed with (hot) water beforehand, I do that a day ahead. 

I haven’t tried bentonite, but it’s a time honored plasticizer for clay bodies.

Of course, you could also make a ton of tiles. When life gives you lemons…  

[Min]

Babs, have you tested that there is nothing else wrong with the clay? Tested absorption? If it's okay other than being short first thing I would try would be adding some bentonite as whiteness isn't an issue and it's inexpensive. If we go on the clay being moist enough and pugged with a deairing pugger it should be okay to throw without aging. If you go on the clay having approx 20% water (+/- 1 or 2%) try 4% bentonite. Example if you have 10 lbs of pugged clay it will be approx 2 lbs water plus 8 lbs dry clay materials. 4% of 8 lbs would be 0.32 lbs (or 145 grams). I would take the 145 grams of bentonite and sprinkle it on about 500 ml of hot water, let it sit without stirring until it sinks then use an immersion blender / stick blender and blend the heck out of it so it makes a thick gloppy paste, really mix it! (might need more water) I'ld then take your 10 lbs of clay and slice it up and spread the bentonite gloop between the layers. After letting it sit for a bit run it through your pugger a few times and see how it throws. Nerds mix could work too but it's adding more variables to the mix.

Edited September 5, 2022 by Min

[Babs]

@Kelly in AK, @Min @Hulk well yes a tonne is a lot but it is under a bench andso not in my face.

I pugged up with reclaim and slops and Glazenerd's magic powders,  left a few days and yesterday threw a few platters and a big cylinder or two.

Such a difference, going back down this a.m.!

Just watch my bone density surge!

And re Company  don't think I am that special that It would keep crap clay for me... if lived on mainland I'd prob have return it.

Re moisture, I slit off top of bag, pierce, not to bottom of clay block,  the clay with a tent peg in a series of rows. Fill those holes with water.

Store in lidded polystyrene vegie box for a few days.

I double bags the vlay as I take it off the pallet to store in  potting shed.

 

[rfbceramics]

Hello all,

I've been working through clay bodies trying to find a cone 6 red body for working with soft slabs: highly plastic, workable, without grog, so I can maintain a smooth surface finish. 

I began with this Brown Clay Body: 60% Redart, 15% Goldart, 15% Ball, 10% silica. When mixed as homogenized as slip and then dried to workable, it behaves beautifully. However, when mixed dry, it is incredibly short and even after weeks of letting it sit, it is still unworkable for my purposes: unable to stretch and bend as a slab. When reclaiming the clay, if I do not blunger it, it remains short. 

I tweaked the recipe to 50% Redart, 15% Goldart, 17.5% Ball, 7.5% XX-Sagger, 10% Hawthorn 50 mesh. This seemed to give me slightly more workability and is still fully vitrified at cone 6 (0.25% absorption). When I mixed the recipe dry by hand in smaller batches to mimic the limited mixing of a Soldner mixer, it remained significantly plastic. However, I just mixed a 100lb batch in a Soldner mixer and it is unworkably short. 

Mixing in the Soldner: 27lbs water. Added Redart and mixed as I have found Redart to be a bit of a water hog. Then added goldart, ball, xx-sagger, and hawthorn. 

Any ideas on the materials or suggestions on a highly plastic, workable, vitreous, red clay body? 

Thanks in advance!

[Kelly in AK]

Hey there, 

Welcome. I appreciate your sharing what you’ve been doing and results. I can’t say I have an answer to the problem, but I’ve certainly experienced it. Inconsistent behavior from a single recipe. When this comes up in discussion concerning recycled scrap people will often say it’s about losing a percentage of the fines and suggest being careful not to discard any slip. I’m not convinced that’s the main problem. 

I believe it’s more due to particle wetting and ph. The conclusion about ph comes from the experience(s) of recycling a few hundred pounds of scrap that’s been sitting in a bin for months under a layer of water. Total slop, fully wetted. What went in was nicely plastic. What came out after dewatering and pugging was horribly short. So the thought is, after sitting so long, solubles in the clay leach out and change the chemistry. I’ve heard vinegar as a remedy for ph problems, but can’t speak to that with experience. Perhaps someone else can.

As to particle wetting, I think it’s a more complex process than it appears. Your description validates this. I’ll point to Veegum, a plasticizer I regularly use. The manufacturer states it will not achieve its true plasticity unless fully hydrated, and that is no mean feat. Hot water and a LOT of mixing. One pound will completely gel a five gallon bucket of water. If you just dump it dry into your clay mix it will never hydrate properly, even if well dispersed, and you’re just wasting it.

Those are my thoughts. Maybe mixing your clay on the more wet side, or perhaps slaking the more plastic ingredients (ball clay) overnight before any mixing occurs could make a difference. Good luck! 

[glazenerd]

9 hours ago, rfbceramics said:

Hello all,

I've been working through clay bodies trying to find a cone 6 red body for working with soft slabs: highly plastic, workable, without grog, so I can maintain a smooth surface finish. 

I began with this Brown Clay Body: 60% Redart, 15% Goldart, 15% Ball, 10% silica. When mixed as homogenized as slip and then dried to workable, it behaves beautifully. However, when mixed dry, it is incredibly short and even after weeks of letting it sit, it is still unworkable for my purposes: unable to stretch and bend as a slab. When reclaiming the clay, if I do not blunger it, it remains short. 

I tweaked the recipe to 50% Redart, 15% Goldart, 17.5% Ball, 7.5% XX-Sagger, 10% Hawthorn 50 mesh. This seemed to give me slightly more workability and is still fully vitrified at cone 6 (0.25% absorption). When I mixed the recipe dry by hand in smaller batches to mimic the limited mixing of a Soldner mixer, it remained significantly plastic. However, I just mixed a 100lb batch in a Soldner mixer and it is unworkably short. 

Mixing in the Soldner: 27lbs water. Added Redart and mixed as I have found Redart to be a bit of a water hog. Then added goldart, ball, xx-sagger, and hawthorn. 

Any ideas on the materials or suggestions on a highly plastic, workable, vitreous, red clay body? 

Thanks in advance!

1st. understand that hand mixed clay, or even clay mixed in a Soldner will take a week to ten days before plasticity is achieved. 2nd Adding kaolin or Hawthorne will lower plasticity, not increase it: both of these have very low plastic values. The original recipe is 50% Redart, 15% Goldart, 15% Om4, and 10% silica. OM4 is a medium plasticity clay, and it is common to see recipes with 25% OM4 for that reason. C&C ball clay is about 40% more plastic than OM4; and is readily available and cheap. Use the original recipe, and simply change out OM4 for C&C. I dry mix all the ingredients before mixing. Both Redart and Goldart have higher sulfide content, which produces your brown clay at cone 5/6. The final issue would be “soft slabs”? Slabs for tile, or slabs for hand building? High plasticity in clay bodies intended for tile can come back and bite you in the form of warping when drying, and excessive shrinking.

Tom

[C.Banks]

I've waited up to 3 weeks for clay to come around.

If you let your most plastic clays slake overnight your clay will come right sooner than if mixed up all at once from dry.

[rfbceramics]

Thanks all,

I'm using the clay for working in soft slabs for handbuilding.  Trying to balance a smooth finish, workability, and the lack of warping. If anyone has a recipe that is truly a midrange body, less than 0.5% absorption at temperature, I'm here for it. Ideally a body not relying on neph sy to get there. 

Changes to the original recipe:

1. I added the Hawthorn and XX-Sagger which dramatically reduced the warping of the body.

2. Removing Silica: Found that it was contributing to the strange behavior of the body. Removing it reduced the unworkability to some extent. 

3. Reduced the Redart % and increased the % of Ball clay (both XX-Sagger and Old Hickory)

I assume the problem has to do with particle packing and evenly distributed wetting. However, that is where my test of hand mixing workable clay should have gotten me to a less reasonable mix than the soldner. 

Edited November 12, 2023 by rfbceramics

[Min]

Have you tried adding blunged bentonite to the original recipe? What is the goal here, soft slab building for functional wares?

[glazenerd]

RF

You want soft slabs for a particular forming process I assume? Yet, you also have to understand that “soft” clay equals higher water content, which adds to the warping issue. The more water in the clay; the more dried shrinkage, and increased risk of warping. As to your other listed issues:

1. Kaolin and fire clay have very low plasticity: but they have some. If you work centers around slab building/forming: then adding molochite 325 would be advisable. Molochite is a grog, and 325 is used when you are trying to maintain low absorption bodies. Unlike kaolin, molochite adds no plasticity, and actually will reduce plastic properties if used in high %. Start at 5% in small test batches. Molochite 325 is used often in slab/tile bodies to control warping. Do not fall into the trap of: if a little works good, then more will work better.” Adding too much will actually cause cracking when drying. 

2. 10% silica additions in stoneware/red body is the industry norm. If you use a glaze calculator: aim for a 5:1 SiAL ratio (5 parts silica to 1 part alumina)Like all things clay: too much silica can lead to cristobalite formation. Cristobalite will dunt your pieces during the cool down, usually around 400-450F range. 

3. Ball clay is the primary plasticizer in most all clay recipes. Slab/tile bodies need just enough to make it malleable, and too much adds to warping/shrinking issues. Secondly, not all ball clays are the same. 8% Taylor, 15% C&C, and 25% OM4: will all impart roughly the same level of plasticity. Ball clays absorb water, as their plasticity levels increase, and as their % in the recipe increases: likewise total water content increases.  

Tom

[glazenerd]

RF

back for an add.  I understand the dislike of sodium based fluxes in a clay body: not a fan of them myself. However, some flux needs to be present for several reasons. I would recommend potassium in the 10-15% range. I also assume your goal of “less than 0.50” absorption is meant to meet TCA specs for vitreous wall tile?  I can have the long detailed discussion about why fluxes, but for now you get the short form.

Tom

[Pyewackette]

As for "aging" clay - I think a big part of the problems I've had with the studio clay I've been struggling with for years now is the fact that it gets mixed and pugged and is on the studio floor in bins the next day.  Now that they're switching away from it to bagged clay for many purposes, I've noticed that the stuff that has sat around for 2 or 3 weeks between class sessions actually throws a lot better - and its drier.  It is very wet, soft, and short straight out of the pugmill and until recently (like the last month) that's exclusively what we were provided with. When classes are running that's still largely what students get.

My own "reclaim" so far hasn't seemed to suffer much from my method of handling it.  Right now all I have access to is porcelain.  I'm a dry thrower - I don't lose a lot of fines when I throw.  I don't have a lot of water to "reclaim" and I often add it to the bag of my "reclaim", that includes dry trimmings and squashed rejects. Often my "reclaim" is pretty wet.  I'll knead it to mix whatever I have, arch it to dry it out, and when its "dry enough" I wedge it back up and reuse it.  I sometimes mix in some new clay.  Wire wedging really helps when mixing clays of different moisture content as long as its not so wet it sticks to your wedging surface too much.  In which case I didn't wait long enough for it to dry out in the arch.  Otherwise it gets consistent pretty quickly when wire wedged.

I keep about 2 or 3 cups of "throwing" water and then all my slop goes in, well, my slop bucket.  Everybody else just seems to throw their slop in their throwing water.  I can throw about 10 to 15 lbs of clay on that.  Keeping my slop (including failures directly off the wheel) separately from my throwing water just seems easier and more efficient to me, but then everybody else around me is used to using the studio clay that was reclaimed and mixed by studio minions.  They often just dump ALL the throwing water and there goes the fines.  Probably contributes to the studio clay always being short.  When using the studio clay, I usually scooped throwing water off the top of the reclaim bucket which is usually relatively clear/settled when I get there before classes or at the beginning of the day.  Similarly I would scoop "rinse" water out of the reclaim buckets if its not too stirred up to rinse my slop bucket and tools, and add that and my (by then pretty goopy) throwing water back into the bucket.  I don't use a lot of water out of the faucet when cleaning up.

Edited November 13, 2023 by Pyewackette

[Morgan]

SUCH a timely post so thank you!

This may sound naive and I hope I am (not) wrong but I am finally getting around to recycling a ton of laguna frost. frost has its own issues as we all know so I am pretty worried about reclaim. I do it the old fashion way just buckets, plaster etc. I save ALL slurry and it is super duper slippy. After say, a half day of throwing my water bucket is already full and needs to be emptied into the slop bucket, usually dump it twice if its a true cranking it out throwing day. I throw semi dry and have never been used to this much slip but alas here we are.

Anyway, my point/question is...am I wrong to simply assume that if you truly keep ALL the fine particles from the throwing slurry and mix that in some proper ratio with scraps/trimmings you could technically get it proper? Seems like nothing is really lost...how else could you be losing all the goodies? I am testing a small batch now, was not aged at all, for just handles (literally drying now) and crossing my fingers. I don't even wanna think about frost cracking issues with reclaim but I am sure it will be a nightmare. Given where I live and cost of materials being what they are reclaim is that much more important financially. To put it in perspective I got 50lbs of reclaim from around 400 lbs of used Frost. I have no idea if that is a lot or a little but sure as heck seems like quite a lot (I also am a minimalist when it comes to trimming/feet etc) compared to my other reclaiming clay bodies.

Thanks!

EDIT: I take that back I have been slowly pouring out clear water into a new throwing container so maybe that contains some of the original magic?

Edited November 14, 2023 by Morgan