Tom Buck on sun 6 jun 04
Ron, others:
I attended the Indy conference, and one of technical sessions
featured Professor Carty of Alfred University. His "paper" amounted to a
discussion of the chief factors that cause wasters (pot losses). While
firing practice had a bearing on this, he voiced the view that claybody
preparation (especially mixing) had a dominant role in the behaviour of
pots made from a given claybody. As a researcher for whiteware
manufacturers, Dr Carty was mostly concerned with warping and cracking.
But clearly his studies tie-in to Ron Roy's concern over absorption and
body maturity to keep absorption within the limits generally accepted for
the holding of water.
Since Dr Carty's paper will be published soon in the NCECA 2004
Conference Journal, I will avoid "stealing his thunder" and stay to his
main point, namely, that the method of mixing claybody ingredients can be
directly related to warping/cracking in the firing process.
Ron, you noted that careful choice of raw materials will yield
a claybody that meets absorption target for a specified cone; especially
for mid-fire and high-fire bodies. You warned, however, that the common
claybody raw materials exhibited sufficient variability over time to
introduce a factor difficult to control and thus ensure absorption targets
are met without on-going testing of new batches.
Now, thanks to Dr Carty, you can also add the need for consistent
mixing practice. Dr Carty showed slides that gave a graphic demonstration
of how mixing affected slumping and cracking. Dr Carty's study gave
support to his view that "high-shear" mixing is essential for best
prepartion of a claybody.
If those Clayarters who mix/prepare their own claybodies want
more information on this factor, I recomend they seek a copy of Dr Carty's
paper.
In summary, a good claybody that fulfills a potter's need requires
a good recipe using raw materials of consistent analysis and the body also
should be mixed in the best possible way.
later. peace Tom.
Tom Buck ) -- primary address.
"alias" or secondary address.
tel: 905-389-2339 (westend Lake Ontario, province of Ontario, Canada).
mailing address: 373 East 43rd Street, Hamilton ON L8T 3E1 Canada
william schran on mon 7 jun 04
Tom wrote:> As a researcher for whiteware manufacturers, Dr Carty was
mostly concerned with warping and cracking.<
> Now, thanks to Dr Carty, you can also add the need for consistent
mixing practice. Dr Carty showed slides that gave a graphic demonstration
of how mixing affected slumping and cracking. Dr Carty's study gave
support to his view that "high-shear" mixing is essential for best
prepartion of a claybody.<
After reading this I wondered about the process of mixing clays and
how that clays are used. I would suspect in industrial applications
clays would be mixed, not allowed to age (just an assumption) and
used as a slip (for molds), moist clay for jiggering/jollying or
barely moistened clay for ram press process. Since the clay may have
no time to "age", complete mixing becomes critical, especially where
little water is used.
For studio potters, it's desirable to allow the clay to age for a
period of time and I would suspect this might compensate, to some
extent, for less than complete mixing.
Yet, at the same time, folks such as Mel take their "new" clay out of
the bag and run it through the pug mill. I would suppose the shearing
action in the pug mill would mix the clay more completely resulting
in a stronger clay body.
Just thinking out loud.
Bill
mailtoandrew@FSMAIL.NET on mon 7 jun 04
Dear Tom, Bil & anyone else,
The NCECA 2004 Conference Journal ....
Just a couple of points and questions:
Now I neither attended the lecture nor read the paper but.... intimate
blending of raw materials is of course essential. The type of mixing can
have a profound influence; such as overblunging of kaolin diminishes
casting properties. Anyway it sounds like it should be an interesting read.
The only widely used ageing Ive known in industry is that of casting slip
where one or two days are allowed for the rheological properties to
stabilise before use.
By far the most widely used method of body preparation is to start with
slip before de-watering by filter presses and vacuum pugged for both for
jiggering/jollying and ram press. Casting slip can be made directly or to
re-disperse plastic body, the latter being preferable. Granulate for
pressing methods can again be made either directly or directly before
spraying drying.
Pugs shouldnt really be thought of as mixers; whilst a certain amount does
occur within the barrel consider that in its most basic form its simply a
tube through which a body forrced.
My question ... for a body prepared from processed raw materials what does
ageing do?
Im aware that ancient chinese potters would leave clay exposed to the
elements for many years, apparently some for so long it was left for
following generations, but this weathering is not what modern potters are
doing.
One place I worked had an established practice of standing extruded body
for 24 hours before making. During a particularly busy period this became
a problem, mainly lack of space and a bottle neck, so a trial was
undertaken to investigate the difference between fresh and aged body? The
difference? None .. nothing in the making characteristics and nothing in
the level of losses.
Can anyone present a plausible explanation why ageing can be necessary?
What improvement does it give?
What happens if its not done?
What is the mechanism that changing the body?
Has anyone done any controlled trials?
Im interested in peoples experience on this.
Regards,
Andrew
Brant Palley NMCLAY.com on tue 8 jun 04
Aging allows the water to completely coat the clay particles, unless you
blunge and filter press (mix into a thin slip and then dry in a press or
on the floor on absorbent material). The way we (NMCLAY) mix clay is to
dry blend in a ribbon blender, mix the powdered clay body in a pug mill
with water and then extrude in a vacuum extruder. This process only takes
one hour and allows very little time for the water to contact the clay.
The hardness (Pentrometer) reading for the clay changes over time,
fireclays like Hawthorne take a week to absorb the water completely making
the clay harder. Water amount is critical to get the firmness of the clay
correct when it is sold. Nepheline Synite has the opposite effect of
deflocculating the clay over time making it softer.
The extruders (Pugmills) themselves do a lot of particle sorting by
accelerating the inside of the extrusion faster than the outside creating
a shear or auger memory in the extrusion. Aging may help cure this auger
memory as does varying the particle size of the ingredients
Brant Palley
nmclay.com
Ivor and Olive Lewis on tue 8 jun 04
Dear Tom Buck,
You say ". Dr Carty's study gave support to his view that
"high-shear" mixing is essential for best preparation of a claybody "
In this context, what is meant by "High Shear". Is this concerned
with the degree of shredding during mixing or is of the nature of
spreading thinly and reforming under pressure? To what extent was
time a factor in his
I have always thought that clay, put through any form of pug mill, is
not processed for a long enough period of time to attain uniform or
homogeneous properties. What is your opinion on this point?
Best regards,
Ivor Lewis. Redhill, South Australia
Potters Council Member
Jim Murphy on tue 8 jun 04
Hi again Andrew,
Since you probably haven't yet read my first post - due to time-zone
difference - let me clarify part of what I had indicated in my previous
post:
"Some of the latest research, including Dr. Carty's, suggest(indicate?)
divalent cation (Ca2+, Mg2+, Na+, K+) concentrations change with time and
correlate with the associated rheological swings in a plastic body."
To be more precise, Na+ and K+ are, of course, NOT divalent. A Carty study
monitored the concentrations of all the cations mentioned above in specially
prepared, mixed & centrifuged (to remove the particles) suspensions. It was
ONLY the divalent cation concentrations, i.e. Ca2+ and Mg2+, which appeared
to correlate strongly with the rheological swings.
The implication of this and further studies suggesting the greater influence
imparted by divalent cations on cohesion/plasticity over time (aging).
Also, for porcelain bodies, cohesion will decrease rapidly with increasing
water content. Carty noted the typically low water contents (19-22%) for
jiggering and ram pressing porcelain bodies. Due to these low water
contents, the bodies have extremely low cohesion. During the jiggering or
ram pressing forming process, more water is removed from the body, causing a
substantial increase in the cohesion of the body - the body stiffness
increases dramatically during forming while keeping pressure dependence
nearly constant.
Additionally, per Carty, "In the case of extrusion (as would be observed in
the manufacturing of electrical insulators), the water contents are
generally lower, much closer to the peak cohesion values, so the removal of
water is less critical."
So Andrew, perhaps "aging" may be less important for certain bodies used in
extrusion.
Best wishes,
Jim Murphy
David Beumee on tue 8 jun 04
Pete Pinnell told our class at Anderson Ranch some years back that 99% of aging was getting the clay completely wet to begin with. In regards to one generation of Chinese potters leaving clay for the next, I remember him saying that moist (buried) clay would probably not have been particularly workable due to leaching of soluble alkalis over time.
I've always noticed a big difference in workability between "dry mixed" commercial clay and wet mixed recycled clay. I save trimmings and dry them out and slake them down in plenty of water and screen the slurry, then dry out the slurry in a rack, saving wetter clay for plates and platters and drier clay for vertical forms. I run all recycled clay through a deairing pugmill. I'm now working with Dr. Carty to find out why tiny bloats appear in the (cone 10) fired recycled clay only, not the original commercially clay.
David Beumee
Earth Alchemy Pottery
Lafayette, CO
> Dear Tom, Bil & anyone else,
>
> The NCECA 2004 Conference Journal ....
>
> Just a couple of points and questions:
>
> Now I neither attended the lecture nor read the paper but.... intimate
> blending of raw materials is of course essential. The type of mixing can
> have a profound influence; such as overblunging of kaolin diminishes
> casting properties. Anyway it sounds like it should be an interesting read.
>
> The only widely used ageing Ive known in industry is that of casting slip
> where one or two days are allowed for the rheological properties to
> stabilise before use.
>
> By far the most widely used method of body preparation is to start with
> slip before de-watering by filter presses and vacuum pugged for both for
> jiggering/jollying and ram press. Casting slip can be made directly or to
> re-disperse plastic body, the latter being preferable. Granulate for
> pressing methods can again be made either directly or directly before
> spraying drying.
>
> Pugs shouldnt really be thought of as mixers; whilst a certain amount does
> occur within the barrel consider that in its most basic form its simply a
> tube through which a body forrced.
>
>
> My question ... for a body prepared from processed raw materials what does
> ageing do?
>
> Im aware that ancient chinese potters would leave clay exposed to the
> elements for many years, apparently some for so long it was left for
> following generations, but this weathering is not what modern potters are
> doing.
>
> One place I worked had an established practice of standing extruded body
> for 24 hours before making. During a particularly busy period this became
> a problem, mainly lack of space and a bottle neck, so a trial was
> undertaken to investigate the difference between fresh and aged body? The
> difference? None .. nothing in the making characteristics and nothing in
> the level of losses.
>
> Can anyone present a plausible explanation why ageing can be necessary?
> What improvement does it give?
> What happens if its not done?
> What is the mechanism that changing the body?
> Has anyone done any controlled trials?
>
> Im interested in peoples experience on this.
>
> Regards,
>
> Andrew
>
> ______________________________________________________________________________
> Send postings to clayart@lsv.ceramics.org
>
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>
> Moderator of the list is Mel Jacobson who may be reached at melpots@pclink.com.
mailtoandrew@FSMAIL.NET on tue 8 jun 04
Dear Ivor,
Whilst acknowledging I neither attended the lecture nor read the paper I
wondering whether the "high-shear" mixing refers to certain types of
blungers which are often referred to as such.
Traditional designs are sometimes known as =93Dolly blungers=94 and have a
small number of angled, horizontal blades on the shaft rotating at around
60 rpm. Whilst high speed, or high shear, blungers have a single impeller
at the bottom of the shaft that rotates at extreme high speed, producing a
vortex in the slip, and generates a highly energetic action.
I would agree that pugging does not ensure a homogeneous blend ... rubbish
in rubbish out sort of thing. Simplistically its a tube down which body
forced: Shearing occurs, which can modify the body=92s properties, .....
with a vacuum box the body can be deaired .... but as a mixer its an
ineffective mixer.
Regards,
Andrew
Jim Murphy on tue 8 jun 04
Hi Andrew,
For plastic bodies, an article of interest to you may be "The
Characterization Of Plasticity" written by none other than Dr. Wiliam Carty
and Cheol Lee, published by The American Ceramic Society in the book
"Science of Whitewares" (c. 1996).
The above referenced article presents some "aging" data on muller-mixed
prepared samples of a variety of clay mixtures including a 30/14/23/33
Porcelain Body (Ball Clay, Kaolin, Quartz, Feldspar).
I'm working right now mostly with casting slip, so I'll make NO claim
whatsoever to having personal "experience" with lots of plastic bodies. I
have, however, read the above referenced article and I'll follow with my
comments to your questions based on my understanding - however limited that
may be... you have been warned !
Briefly, to paraphrase from the article, plasticity of a clay body may be
characterized based on the underlying principle of a Bingham fluid whereby
the "Shear Yield Stress" will increase with increasing "Applied Pressure".
Also, the pressure dependence of samples changes as a function of water
content. For a plastic body, if one were to plot "Shear Yield Stress"
(y-axis) vs. "Applied Pressure" (x-axis), the Cohesion would be the y-axis
"intercept" and Pressure Dependence would be the "slope".
What is very important to understand is the "changes" both Cohesion and
Pressure Dependence undergo over time (aging). Varying Cohesion and Pressure
Dependence affect claybody performance.
With respect to your specific questions, then, Andrew:
> Can anyone present a plausible explanation why ageing can be necessary?
To allow Cohesion and Pressure Dependence to reach a steady-state
condition - about 3-days for the tested 30/14/23/33 Porcelain Body.
(Cohesion and Pressure Dependence varied widely during the first 2+ days).
From the study, a mixture of Ball Clay and 22% de-ionized water (on a dry
weight basis) took much longer - over 10 days to reach steady-state.
Non-plastics (quartz and feldspar) may accelerate the "aging" process.
> What improvement does it give?
Better plasticity, less warping, deformation, etc.
Also important for bodies with non-plastics (Quartz and feldspar), high
cohesive stresses may be obtained at lower water content.
> What happens if its not done?
Warping, cracking, deformation, tall buildings toppling without assistance
from King Kong or Godzilla.
> What is the mechanism that changing the body?
Could be it takes time for the water to be "structured" per Brownell,
Kingery, etal. Some of the latest research, including Dr. Carty's,
suggest(indicate?) divalent cation (Ca2+, Mg2+, Na+, K+) concentrations
change with time and correlate with the associated rheological swings in a
plastic body.
> Has anyone done any controlled trials?
William Carty & Cheol Lee.
Hope this helps.
Best wishes,
Jim Murphy
mailtoandrew@FSMAIL.NET on tue 8 jun 04
Dear Brant and David,
So for a body prepared by the standard wet route ... slop non-plastics or
powdered dispersed in water than blended with separately blunged clays,
followed by screening, magneting and filter pressing .... would you
consider that ageing would be of little benefit?
I certainly agree with Brant=92s comment that =94inside of the extrusion
faster than the outside=94 ... viz the differential in flow rate across the
river where its slow by the banks and faster in the centre. The rotation
of the auger is associated with S cracks in ware and its pattern can be
detected, and can be highlighted. Either by taking a slice of the
extrusion, say 1=94 thick, or freezing it or by dusting a powdered dye
across some the feed body. The latter also demonstrates the
ineffectiveness of pugs as mixers.
However Im not sure that ageing could alleviate this auger memory: this
sounds like one of the claimed reasons for the 24 hour hold on freshly
extruded body that was investigated in the trial I referred to in my
earlier post. It was also claimed the delay allowed stresses to be
relieved and moisture variation to even out. No support could be found as
well as evidence to contradict.
Brad have you any evidence to support the ageing / easing of auger memory?
Thoughts and observations are welcomed,
Regards,
Andrew
Ivor and Olive Lewis on wed 9 jun 04
Dear Brant Palley,
Thank you for describing your commercial preparation of clay.
I do not know what a "Ribbon blender" is. What is it and how does this
work?
You say "....fireclays like Hawthorne take a week to absorb the water
completely making the clay harder....". Is this because fireclays are
porous, like bisque grog so they behave like a sponge?
Best regards,
Ivor Lewis
Brant Palley NMCLAY.com on wed 9 jun 04
No, the only cure is to incorporate sand or grog in the 100 mesh range.
Brant
Ivor and Olive Lewis on wed 9 jun 04
Dear Andrew,
Thank you for those notes.
Though it is a long time ago that I had use of pug mill in the
classroom, my students always put reclaimed clay through the machine
at least three times, taking care to rotate the clay so that the
original spiral structure was destroyed. They also kneaded the clay
before using it.
Best regards,
Ivor Lewis. Redhill, South Australia
Ron Roy on wed 9 jun 04
There is no doubt that aging clay improves platicity due to the changes in
ph - unless those changes are to the alkaline side.
The way I have understood this from reading is - bacteria add acid which
promotes flocculation. Adding vinegar does the same thing although I don't
recommend that except for immediate use - as in thickening slip.
Most clay companies design bodies to be immediatly plastic enough for
immediate use.
In the old days - when plasticisers or plastic clays were not available
locally - aging was the way to make short clays workable.
I am not offering any science in this - except that flocculation does
improve workability up to a point. I do have extensive experience however -
when opening an old bag of clay - I know it will be a treat to work with.
I don't think a day or a week would do much to make short clay workable -
but a few months in a warm place will - unless there is alkaline leaching
from material in the body - which will have the opposite effect.
RR
Ron Roy
RR#4
15084 Little Lake Road
Brighton, Ontario
Canada
K0K 1H0
Phone: 613-475-9544
Fax: 613-475-3513
mailtoandrew@FSMAIL.NET on wed 9 jun 04
Helo Jim,
Yes youre right I hadnt read your earlier post; Ill print out all the
posts on this thread and together with the Science of Whitewares as per
your reference, just got it out of the library, Ive enough reading for
tonight!
If you can track it down for a very goog consideration of plasticity in
whiteware bodies Plasticity, A Critical Survey by E.C.Bloor.
The full citation is Trans. Brit. Ceram. Soc. 56, 423, 1957. ... just
noticed its also referenced in the article by Onoda that proceeds that by
Carty/Lee.
Thanks,
Andrew
mailtoandrew@FSMAIL.NET on thu 10 jun 04
Hello Roy,
Thanks for your interesting thoughts.
Could you elaborate?
Have you measured a pH change with time for plastic bodies?
Do you know of any work to measure a bacteria increase with time, and in
particular associated with increased plasticity?
How was the increase in plasticity assessed: potters thumb or more
quantitative methods?
Does the ageing effect wet processed bodies equally to dry blended?
Would others agree with Roy that months rather than a few days is needed?
Regards,
Andrew
John Britt on thu 10 jun 04
Andrew,
I don't have quantitive data, but when I make porcelain I put apple cider
vinegar and some beer in the mix. I then let the clay age and it grows
some wonderful stuff which is visible when you slice it open. It is mainly
black and when you wedge it the white porcelain turns grey. After the
pieces are trimmed they will turn white as the bacteria dies. It seems
more plastic than the fresh stuff, but no objective data.
John Britt
www.johnbrittpottery.com
mailtoandrew@FSMAIL.NET on fri 11 jun 04
Hello John,
Thanks for the info.
Well cider vinegar and beer ... lucky bacteria is all I can say!
Regards,
Andrew
Ron Roy on sun 13 jun 04
Hello Andrew,
I have not done any specific experiments on PH.
My observations are based on reading and experience.
The reading part - bacteria can become active when clay is stored in the
plastic form - a warm place is conducive - and the waste products (acids)
promote what we call plasticity. Pulling handles with fresh clay is not as
easy as with "aged" clay for instance.
Wedging clay after it has been aged for some time is said to add oxygen and
rejuvenate the bacteria so aging proceeds at a fast rate.
The experience part - Opening a bag of old clay and getting that fresh
"earth" smell is usually the tip off that throwing and forming is going to
be easier.
The test I would use to see the difference between old and new clay is -
roll a short coil of each and pull on both ends - if the clay breaks with
out narrowing at the point of separation then it is not of optimum
plasticity. If the clay narrows before breaking you have more plastic clay
- the more it narrows before it breaks the more plastic it is. The coil
around the finger is another test - the smaller the coil without breaking
the more plastic the clay is.
The interesting part about aged clay is - it is more plastic (say
stretchability without coming apart) but it does not shrink more because of
the aging - in other words to get the same plasticity in fresh you would
need to add plasticizers and increase shrinkage.
There is another way to get more plastic clay without aging - add the waste
products of bacteria when mixing - like vinegar. Not recommended because of
the rotten smell is a short time. The other way would be to add something
like Epsom Salts - instant aging - works well and counteracts the
propensity of porcelains - especially those made with Neph Sy - to deflocc.
Not very scientific I know but give me a choice between aged and fresh and
I will choose aged - unless the clay is deflocced - then it would be the
fresh.
Does aging affect wet processed clay the same as dry mixed with just enough
water to get workable clay - I don't know - my experience has been with the
later. Perhaps the question should be - does it take less aging for wet
processed than for the dry processed.
Just as side comment - most dry mixed clay is not mixed very well due to
the kind of macinery used - Tuckers has an Irex mixer - I would be
interested to compare that method with wet mixed.
There was a time when Tuckers did have a wet mix section - potters were not
willing to pay the extra cost for that clay - perhaps that says something
about the issue.
Regards - RR
>Thanks for your interesting thoughts.
>
>Could you elaborate?
>
>Have you measured a pH change with time for plastic bodies?
>
>Do you know of any work to measure a bacteria increase with time, and in
>particular associated with increased plasticity?
>
>How was the increase in plasticity assessed: potters thumb or more
>quantitative methods?
>
>Does the ageing effect wet processed bodies equally to dry blended?
>
>Would others agree with Roy that months rather than a few days is needed?
>Regards,
>Andrew
Ron Roy
RR#4
15084 Little Lake Road
Brighton, Ontario
Canada
K0K 1H0
Phone: 613-475-9544
Fax: 613-475-3513
Roger Korn on mon 14 jun 04
RR wrote:
...
The experience part - Opening a bag of old clay and getting that fresh
"earth" smell is usually the tip off that throwing and forming is going to
be easier...
I'd like to add that the green mold on the surface of the bagged clay is
useful as an "indicator". Keep wedging until the green is evenly
distributed, then you have a really workable clay body. Ideally, you are
working with clay your ancestors dug, refined, and maintained in a clay
pit, per the Japanese/ Korean mythos.
Roger
--
McKay Creek Ceramics
In OR: PO Box 436
North Plains, OR 97133
503-647-5464
In AZ: PO Box 463
Rimrock, AZ 86335
928-567-5699
Ivor and Olive Lewis on wed 16 jun 04
Dear Roger Korn,
The next time I get a bag with this green film I will take a sample
and have a look at it. I have a feeling this might be an Algae, could
be Chlorella. So the decomposition residues would contain Alginate's.
As little as one percent of some of the alginate's can turn liquid
water into a solid or semi-solid substance.
What interesting lives we lead.
Best regards,
Ivor Lewis.
Redhill,
S. Australia.
Ivor and Olive Lewis on thu 17 jun 04
Dear Des,
As I understand things, Humic Acid is the penultimate stage in the
decomposition of Plant and Animal Material in surface soil. (Then nest
step gives water and Carbon dioxide) It is the main constituent of
Humus, a colloid which has the ability to latch on to mineral
nutrients and is a major source for minerals for new growth.
In 1970 I did some work on the use of Marine Algae (Seaweed) as a soil
supplement. One of the things these plants are able to do is sequester
metallic ions from solutions. I found they were very good at taking up
Iron from solutions of the salts of that element.
Alginic acids form strong Gels.
It would be good if the organisms could be isolated and identified.
Best regards,
Ivor Lewis.
Redhill,
S. Australia.
Roger Korn on thu 17 jun 04
I'll dig into this myself next winter. My student optical microscope and
a few stains should suffice for ID purposes. Please pursue this also, so
that we can come up with independent results. Come to think of it, the
first couple of wedging slams do produce a thixotropy-like sudden
softening of the clay, beyond the usual, so your alginate hypothesis
sounds good.
Many thanks for the info,
Roger
Ivor Lewis wrote:
The next time I get a bag with this green film I will take a sample
and have a look at it. I have a feeling this might be an Algae, could
be Chlorella. So the decomposition residues would contain Alginate's.
As little as one percent of some of the alginate's can turn liquid
water into a solid or semi-solid substance.
--
McKay Creek Ceramics
In OR: PO Box 436
North Plains, OR 97133
503-647-5464
In AZ: PO Box 463
Rimrock, AZ 86335
928-567-5699
Des & Jan Howard on thu 17 jun 04
Ivor
I seem to remember that decaying matter produces humic acid which I gather is a gel like substance.
(Check out Google, humic acid can bring about world peace & make good coffee . )
Des
Ivor and Olive Lewis wrote:
> So the decomposition residues would contain Alginate's.
> As little as one percent of some of the alginate's can turn liquid
> water into a solid or semi-solid substance.
> What interesting lives we lead.--
Des & Jan Howard
Lue Pottery
LUE NSW 2850
Australia
Ph/Fax 02 6373 6419
http://www.luepottery.hwy.com.au
Fredrick Paget on thu 17 jun 04
>.
>In 1970 I did some work on the use of Marine Algae (Seaweed) as a soil
>supplement. One of the things these plants are able to do is sequester
>metallic ions from solutions. I found they were very good at taking up
>Iron from solutions of the salts of that element.
>Alginic acids form strong Gels.
>It would be good if the organisms could be isolated and identified.
>Best regards,
>Ivor Lewis.
For some years I have been buying clay and lazily keeping it for
several years before using it. I get lots of that green algae in the
bags.
Back in the 70's we used to have a community garden in Rockport,
Massachusetts, USA.
One of the things we always did was make a huge pile of compost of
leaves , seaweed, manure, and limestone, cover with old carpets and
let her cook all through the winter; the local beach was covered in
seaweed 2 feet deep in the fall. I remember loading my 3/4 ton pickup
with about 4 tons of it and breaking down with a flat tire in the
middle of downtown. It was down so far on the springs that we
couldn't get a regular jack under it and had to send for a hydraulic
jack to fix the tire. Great compost! Great for the soil tilth too, we
were on a hillside in a soil made from decomposed granite. Rockport
has underlying granite - used to be a big supplier of granite for
building the cities of the East Coast.
Fred Paget
Back from China - Shanghai, Yixing, Jingdezhen ,Kunming and points
southwest and raring to go. Tozan firing only 2 months off.
--
From Fred Paget, Marin County, California, USA
fredrick@well.com
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